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From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Newsgroups: sci.astro,alt.sci.planetary,alt.astronomy
Subject: Planet Hunters On Trail Of Worlds Smaller Than Saturn
Date: 29 Mar 2000 18:43 UT
Organization: Jet Propulsion Laboratory
PLANET HUNTERS ON TRAIL OF WORLDS SMALLER THAN SATURN
Planet-hunting astronomers have crossed an important
threshold in planet detection, with the discovery of two planets
that may be smaller in mass than Saturn.
Of the 30 extrasolar planets around Sun-like stars detected
previously, all have been the size of Jupiter or larger. The
existence of these Saturn-sized candidates suggests that many
stars harbor smaller planets, in addition to the Jupiter-sized
ones.
...
The discovery was made by planet-sleuths Marcy, Paul Butler
of the Carnegie Institution of Washington, and Steve Vogt of the
University of California, Santa Cruz, using the mighty Keck
telescope in Mauna Kea, Hawaii. They discovered a planet at least
80 percent the mass of Saturn orbiting 3.8 million miles from the
star HD46375, 109 light-years away in the constellation Monoceros,
and a planet 70 percent the mass of Saturn orbiting 32.5 million
miles around the star 79 Ceti (also known as HD16141), located 117
light-years away in the constellation Cetus.
These planets are very close to their stars and so have short
orbits. They whirl around their parent stars with periods of 3.02
days and 75 days respectively. This allowed for their relatively
rapid discovery.
The astronomers detected the small wobble of a star caused by
the gravitational tug of the unseen planets. For the past five
years Marcy and Butler have used this technique successfully to
catalog 21 extrasolar planets. Boosted by the light-gathering
power of Keck, they have steadily increased the precision of their
measurements so they can look for the gravitational effects of
ever-smaller bodies. In this latest detection, the change in a
star's velocity -- rhythmically moving toward and then away from
Earth -- is only 36 feet per second, a little faster than a human
sprints.
The Saturn-mass planets are presumably gas giants, made
mostly of primordial hydrogen and helium, rather than the rocky
material Earth is made of. They are so close to their parent stars
they are extremely hot, and are not abodes for life as we know it.
The planet orbiting 79 Ceti has an average temperature of 1530
degrees Fahrenheit (830 degrees Celsius). The planet orbiting
HD46375 has an average temperature of 2070 degrees Fahrenheit
(1130 degrees Celsius).
...
14 Feb.: The 32nd planet candidate found around HD 12661 by the SFSU Team.
8 Feb.: The 31st planet found by the AFOE Team around HD 89744
From: NAEF Dominique (Dominique.Naef@obs.unige.ch)
Date: Tue Jan 25 2000 - 12:25:43 UTC
Subject: Extrasolar Planet detected around GJ 3021
To: "List 'Exoplanets'"
A Planetary Companion around the Young Dwarf Gliese-Jahreiss 3021
=================================================================
D. Naef , M. Mayor, F. Pepe, D. Queloz, N.C. Santos, S. Udry, M. Burnet
Geneva Observatory, 51 ch des Maillettes, 1290 Sauverny, Switzerland
We report here the detection of a planetary companion orbiting the young dwarf
Gliese-Jahreiss 3021 (GJ 3021). The radial-velocity orbit obtained from our 50
measurements has a period of 133.8 +/- 0.2 days, an eccentricity of 0.5 +/-
0.02 and a semi-amplitude of 164 +/- 4 m/s. The inferred minimum mass for the
companion is 3.32 Jupiter mass. The orbital separation between the planet and
its parent star ranges from 0.25 to 0.75 AU. This planet resides within the
habitable zone most of the time. The equilibrium temperature ranges from about
260 Kelvin (apastron) to 440 Kelvin (periastron).
This planetary companion has been discovered with the CORALIE echelle
spectrograph mounted on the 1.2m "Leonard Euler" Swiss telescope at ESO-La
Silla observatory (Chile). It is the fifth detection of the Geneva Southern
Planet Search after only 18 months of operations.
GJ 3021 (HD 1237, HIP 1292) is a bright (V=6.59) G6 dwarf in the constellation
of Hydrus. The precise parallax from the Hipparcos satellite sets the star at a
distance of 17.8 pc from the Sun. It is a chromospherically active star
(log R'_HK = -4.44, Henry et al. 1996). With this activity indicator, we
estimate an age of 0.6 Gyr using the calibration by Donahue (1993). Such a
young age is supported by the fast stellar rotation (Vsini=5.5 km/s) and the
ROSAT X-ray luminosity of GJ 3021 (L_X > 10E29 erg/s) much too high for an old
G dwarf. GJ 3021 has a high metal content ([Fe/H]=0.2).
The large residuals around the best Keplerian solution (O-C=19 m/s) are most
probably related to the star activity level. GJ 3021 is not the first active
star hosting a planet. HD 130322 (Udry et al. 2000), and HD 192263 (Santos et
al. 2000) are also chromospherically active cool stars with giant planets. It
has recently been shown (Saar et al. 1998, Santos et al. 2000) that the
radial-velocity jitter due to activity-related processes is getting smaller for
redder solar-type stars. So it remains possible to search for planets around
late-type active stars with the radial-velocity technique.
We are greatful to F. Kienzle, C. Melo and Y. Revaz for additional
measurements obtained during their own observing runs.
More details and the phase-folded curve of the radial-velocity
measurements can be obtained on our planet-search web page on the
Geneva Observatory web site:
http://obswww.unige.ch/~udry/planet/planet.html
From: Jean.Schneider@obspm.fr
Date: Sun, 14 Nov 1999 13:52:36 +0100
Subject: six new planets discovered by Marcy et al
To: exoplanets@gagax5.obs.ujf-grenoble.fr
Six new planets detected by Marcy et al:
HD 209458,
HD 37124,
HD 177830,
HD 134987,
HD 222582,
HD 10697
All details in the extrasolar planets catalog at
http://www.obspm.fr/encycl/catalog.html
Jean Schneider
From: Andrew Yee
Newsgroups: sci.astro
Subject: Astronomers see shadow of planet cross distant star, proving that
extrasolar planets are real (Forwarded)
Date: Sun, 14 Nov 1999 15:32:37 GMT
University of California-Berkeley
Contact:
Robert Sanders, (510) 643-6998, rls@pa.urel.berkeley.edu
FOR IMMEDIATE RELEASE: 11/12/99
Astronomers see shadow of planet cross distant star, proving that
extrasolar planets are real
Nashville, Tenn., and Berkeley, Calif. -- Astronomers have witnessed for
the first time a distant planet passing in front of its star, providing
direct and independent confirmation of the existence of extrasolar
planets that to date have been inferred only from the wobble of their
star.
"This is the first independent confirmation of a planet discovered through
changes in a star's radial velocity and demonstrates that our indirect
evidence for planets really is due to planets," said Geoffrey Marcy, a
professor of astronomy at the University of California, Berkeley.
Marcy and his colleagues, Paul Butler of the Department of Terrestrial
Magnetism at the Carnegie Institution of Washington in Washington, D.C.,
and Steve Vogt of UC Santa Cruz and Lick Observatory, first detected a
wobble in the star called HD 209458 on Nov. 5. Ascribing the wobble to a
nearby planet, they were able to estimate its orbit and approximate mass.
As with all new planets they detect, the team immediately brought it to
the attention of collaborator Greg Henry, an astronomer at the Tennessee
State University Center of Excellence in Information Systems in Nashville.
He conducts research with several automatic telescopes at Fairborn
Observatory, a non-profit research foundation located in the Patagonia
Mountains of southern Arizona.
Henry turned one of his automatic telescopes on the star at the time Marcy
and Butler predicted the planet would cross the face of the star if the
planet's orbital plane were lucky enough to carry it between Earth and the
star. Until now, none of the 18 other extrasolar planets Marcy and Butler
have discovered has had its orbital plane oriented edge-on to Earth so that
the planet could be seen to transit the star, nor have any of the other
planets discovered by other researchers.
However, on Nov. 7, Henry observed a 1.7 percent dip in the star's brightness.
Because the planet orbits its star once every 3.523 days, he plans to repeat
his observations on Sunday, Nov. 14.
"This planetary transit occurred at exactly the time predicted from Marcy's
observations, confirming absolutely the presence of a companion," Henry
said. "The amount of dimming of the star's light during the transit also
gives us the first-ever measure of the size and density of an extrasolar
planet. We've essentially seen the shadow of the planet and used it to
measure the planet's size."
The star HD 209458 is 47 parsecs (153 light years or 1.4 million billion
kilometers or 859,000 billion miles) away in the constellation of Pegasus,
and is about the same age, color and size as our own Sun. It is very near
the star, 51 Pegasi, around which the first extrasolar planet was
discovered in 1995.
With the orbital plane of the planet known, the astronomers for the first
time could determine precisely the mass of the planet and, from the size
of the planet measured during transit, its density.
Interestingly, while the planet's mass is only 63 percent of Jupiter's mass,
its radius is 60 percent bigger than that of Jupiter. This fits with theories
that predict a bloated planet when, as here, the planet is very close to the
star.
The density, about 0.2 grams per cubic centimeter, means it is a gas giant
like Jupiter. However, such gas giants could not have formed at the distance
this planet is from its star.
"This supports the theory that extrasolar planets very near their star did
not form where they are, but formed farther out and migrated inward,"
Henry said.
Various groups around the world have been searching for planets by looking
for dimming of stars, or as Marcy says, "staring at the sky and seeing if any
star blinks." To date, none of these searches has turned up a new planet.
"With this one, everything hangs together," Marcy said. "This is what we've
been waiting for."
The research was supported by the National Aeronautics and Space
Administration, the National Science Foundation, Sun Microsystems and the
Richard Lounsbery Foundation.
[NOTE: Details are available at
http://astron.berkeley.edu/~gmarcy/transit.html]
Date: Tue, 28 Sep 1999 18:28:26 +0200 (MET DST)
From: SANTOS nuno
Subject: A new extrasolar planet around the star HD 192263.
To: exoplanets@gagax5.obs.ujf-grenoble.fr
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A new extrasolar planet around the star HD 192263.
Santos N., Mayor M., Naef D., Pepe F., Queloz D., Udry S., Burnet M., Revaz Y.
Geneva Observatory, ch des Maillettes 51, CH-1290 Sauverny
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Four years after the discovery of the planet around 51 Peg, more than
20 extrasolar planets have been detected. These planets present a wide
variety of (minimum) masses and kinematic properties, and show that
extrasolar giant planets are rather common around solar-type stars.
Now, the CORALIE survey is adding another object to the extrasolar
planetary list. The planet orbits the star HD 192263 (HIP 99711), a
7.79 apparent magnitude K2 dwarf in the constellation Aquila (The Eagle).
This star has a parallax pi=50.27 +/- 1.13 mas (from the
Hipparcos catalogue), corresponding to a distance of 19.9 pc. The derived
absolute magnitude and luminosity are M_V=5.91 and L=0.34 solar luminosity.
Its metallicity index, obtained from Stroemgren-uvby photometry, has a
value [Fe/H]=-0.20. A similar value of -0.14 is obtained using a
calibration of the CORAVEL cross-correlation dip, confirming its
slight poor metal content.
...
From: Jean.Schneider@obspm.fr
Date: Mon, 06 Sep 1999 10:56:25 +0002
Subject: planet found by Swiss Team around HD 130322
To: exoplanets@gagax5.obs.ujf-grenoble.fr,
Message send by
Dominique.Naef@obs.unige.ch "NAEF Dominique" 4-SEP-1999 15:51:40.72
HD 130322. A third exoplanet detected with CORALIE at La Silla
--------------------------------------------------------------
Udry S., Mayor M., Naef D., Pepe F., Queloz D., Santos N., Burnet M.
Geneva Observatory, ch des Maillettes 51, CH-1290 Sauverny
http://obswww.unige.ch/~udry/planet/hd130322.html
After the detection of 2 extra-solar planets in the Southern sky around Gl 86
and HD 75289 the high-resolution CORALIE spectrograph on the 1.2-m Euler Swiss
telescope at La Silla Observatory is yielding its 3rd planetary candidate in
less than 1 year.
The new extra-solar planet has been detected around the star HD 130322 in the
VIRGO constellation. HD 130322 is a K0 dwarf of apparent magnitude V=8.04 and
color index B-V=0.781. Its metallicity is solar and the luminosity is about
half the solar one. The HIPPARCOS catalogue lists a precise astrometric
parallax pi=33.6 +/- 1.5 mas setting the star at a distance of about 30 pc
from the Sun. The derived absolute magnitude M_V=5.67 invalidates the earlier
giant classification generally found in the literature.
A set of 111 high-precision radial-velocity (RV) measurements over 15 cycles
has allowed us to determine an accurate orbital solution for the system. The
planet orbits its parent star in 10.7 days inducing a RV semi-amplitude
variation of 116 m/s for the star which is easily detected with the precision
level obtained with CORALIE (6-7 m/s). With a small but significant
eccentricity e=0.06 the orbit is almost circular. From the period and mass of
the primary star (0.79 M_Sun), the separation between the planet and the star
is estimated to be 0.08 AU and the inferred mass of the planetary companion
about 1.08 M_Jup. With a period of 10.7 days, the planet belongs to the
"hot Jupiter" family. The temperature estimate at the planet surface is
slightly higher than 1000 deg K. This new candidate furthermore increases
the observed piling up of planets with small orbital separations.
...
From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Newsgroups: sci.astro,alt.sci.planetary,alt.astronomy
Subject: Discovery Of Extrasolar Giant Planet in Earth-like Orbit
Date: 29 Jul 1999 16:01 UT
Organization: Jet Propulsion Laboratory
----------------------------------------------------------------------------
Information from the European Southern Observatory
ESO Press Release 12/99
29 July 1999 [ESO Logo]
For immediate release
------------------------------------------------------------------------
http://www.eso.org/outreach/press-rel/pr-1999/pr-12-99.html
Extrasolar Giant Planet in Earth-like Orbit
Discovery from a Long-term Project at La Silla
A new extrasolar planet has been found at the ESO La Silla Observatory as a
companion to iota Horologii (iota Hor). This 5.4-mag solar-type star is
located at a distance of 56 light-years and is just visible to the unaided
eye in the southern constellation Horologium (The Pendulum Clock).
...
The team that found the new planet, now designated iota Hor b, consists of
Martin Kuerster, Michael Endl and Sebastian Els (ESO-Chile), Artie P. Hatzes
and William D. Cochran (University of Texas, Austin, USA), and Stefan
Doebereiner and Konrad Dennerl (Max-Planck-Institut fuer extraterrestrische
Physik, Garching, Germany).
...
iota Hor b has an orbital period of 320 days. From this period, the known
mass of the central star (1.03 solar masses) and the amplitude of the
velocity changes, a mass of at least 2.26 times that of planet Jupiter is
deduced for the planet.
It revolves around the host star in a somewhat elongated orbit (the
eccentricity is 0.16). If it were located in our own solar system, this
orbit would stretch from just outside the orbit of Venus (at 117 million km
or 0.78 Astronomical Units from the Sun) to just outside the orbit of the
Earth (the point farthest from the Sun, at 162 million km or 1.08
Astronomical Units)
The new giant planet is thus moving in an orbit not unlike that of the
Earth. In fact, of all the planets discovered so far, the orbit of iota Hor
b is the most Earth-like. Also, with a spectral type of G0 V, its host star
is quite similar to the Sun (G2 V).
...
From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Newsgroups: sci.astro,alt.sci.planetary,alt.astronomy
Subject: Astronomers Find Family Of Giant Planets
Date: 15 Apr 1999 17:54 UT
Organization: Jet Propulsion Laboratory
A Family of Giants
Marshall Space Flight Center
http://science.nasa.gov/newhome/headlines/ast15apr99_1.htm
First System of Multiple Planets Found around a Sun-like Star.
FROM A PRESS RELEASE FROM THE AMERICAN ASTRONOMICAL SOCIETY and SAN
FRANCISCO STATE UNIVERSITY
Apr. 15, 1999: Astronomers from four research institutions have discovered
strong evidence for a trio of Jupiter-sized extrasolar planets that orbit
the star Upsilon Andromedae. In a paper submitted to The Astrophysical
Journal, scientists announce the first multiple planet system ever found
around a normal star, other than the nine planets in our Solar System. The
closest planet in the Upsilon Andromedae system was detected in 1996 by
astronomers Geoffrey Marcy and R. Paul Butler from San Francisco State
University. Now, after 11 years of telescope observations at Lick
Observatory near San Jose, CA, the signals of two additional planets have
emerged from the data.
Astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) in
Cambridge, MA, and the High Altitude Observatory (HAO) in Boulder, CO have
independently found the two outer planets around Upsilon Andromedae. This
team has been studying the star for more than four years at the
Smithsonian's Whipple Observatory near Tucson, AZ.
...
From: schneider@obspm.fr
Subject: New extrasolar planet: the lightest of all
Date: Thu, 04 Feb 1999 12:16:36 GMT
The Swiss group from Geneva Observatory, led by Michel Mayor, who
has discovered with Didier Queloz the first planet ever detected around
a solar type star, has announced on February 1 the discovery of
the lightest extrasolar planet around the star HD 75289. The planet,
having an orbital period of about 4 days, is only slightly more massive
than Saturn (0.42 Jupiter mass).
More informations on the Extrasolar Planets Encyclopaedia website:
http://www.obspm.fr/planets
Jean Schneider
Paris Observatory
From: Andrew Yee
Subject: Extrasolar Planet in Double Star System Discovered from La Silla (Forwarded)
Date: Tue, 24 Nov 1998 19:28:10 GMT
Newsgroups: sci.astro
ESO Education and Public Relations Dept.
----------------------------------------------------------------------------
Text with all links is available on the ESO Website at URLs:
http://www.eso.org/outreach/press-rel/pr-1998/pr-18-98.html
----------------------------------------------------------------------------
ESO Press Release 18/98
For immediate release: 24 November 1998
Extrasolar Planet in Double Star System Discovered from La Silla
Early Success With New Swiss Telescope
During the past three years, about fifteen planetary companions have been
discovered in orbits around dwarf stars. They have revealed to
astrophysicists a broad diversity of planetary systems at other stars.
Giant planets with masses ranging from half to several times the mass of
Jupiter, the largest planet in our own solar system, have been detected with
various telescopes. The orbital periods range from 3.1 to 1650 days; while
some of the orbits are of circular shape, others are very elongated. The
observed diversity naturally raises questions about how these exoplanets are
formed.
Now, following only a few months of observations, a Swiss team of
astronomers [1], working with a new Swiss astronomical facility at the ESO
La Silla Observatory mainly dedicated to the search for exoplanets, has made
its first planetary detection. It is a massive planet moving in an almost
circular orbit around a nearby star that is itself the primary component of
a double star system.
...
Discovery of a heavy planet in orbit around "Gliese 86"
Gliese 86 (also known as "HD 13445") is seen in the southern constellation
Eridanus (The River). It is a bright, rather cool dwarf star, somewhat less
massive than the Sun (about 0.79 solar mass). It is also intrinsically
fainter than the Sun (about 0.4 solar luminosity). However, since it is
quite nearby -- about 35 light-years only -- its apparent magnitude is
comparatively bright and it is just at the limit of what can be seen with
the unaided eye (mV= 6.12). Contrary to most stars with known planetary
companions, Gliese 86 contains less metals than our Sun, by a factor of two.
Since September 1998, the Swiss astronomers have obtained 29 high-precision
radial-velocity measurements of Gliese 86. A planet in orbit around a star
will manifest its presence by pulling the star in different directions,
thereby changing by rather small amounts its measured velocity.
ESO PR Photo 45c/98
PR Photo 45c/98 (left) shows the measurements (with error bars) of the
radial velocity (Vr vrs. orbital phase) of Gliese 86 with the new 1.2-m
Swiss telescope and the CORALIE spectrograph at La Silla. They have been
"phase-folded" with a period of 15.83 days and the diagramme thus
represents one revolution of the planet around the star. The fully drawn
line corresponds to the best orbital solution, obtained by least-square
fitting a simple two-body model (star + planet) to the data. As can be
seen, the agreement is near perfect and the dispersion of the measurements
around this line is very small.
The orbit of the new planet (PR Photo 45c/98) has a period of 15.83 days.
The total velocity variation is 740 m/sec, very easy to detect with CORALIE.
The orbit is slightly non-circular and has a small, but significant
eccentricity of 0.05. The dispersion of the radial-velocity values around
the orbital solution is only 7 m/sec; this includes statistical errors,
spectrograph systematic errors and intrinsic stellar variations.
The inferred minimum mass for the planetary companion is 4.9 times the mass
of planet Jupiter. The new planet is at a distance of only 0.11 AU (16.5
million km) from the star, i.e. just over one tenth of the Sun-Earth
distance. The surface temperature on the planet is quite high, about 380 C.
It is the second closest exoplanetary system discovered to date.
...
From: Andrew Yee
Date: 1999/01/11
Subject: Orbits of other distant planets oval -- not circular (Forwarded)
Newsgroups: sci.astro
Public Affairs Office
San Francisco State University
San Francisco, California
Contact: Ligeia Polidora, 415/338-3053
e-mail: ligeia@sfsu.edu
EMBARGOED FOR 9:30 AM CST (7:30 AM PST) SATURDAY (1/9/99) -- TIME OF PRESS
CONFERENCE AT THE AUSTIN, TEXAS MEETING OF THE AMERICAN ASTRONOMICAL SOCIETY
#041
Orbits of other distant planets oval -- not circular
SAN FRANCISCO, CA, January 9, 1999 -- Unlike the nine planets that make
circular orbits around our Sun, all nine of the 17 extrasolar planets which
are in distant orbits around their host stars travel in oval-shaped paths.
This surprising pattern suggests that our heliocentric perspective skews
expectations of worlds elsewhere. The circular paths of planets in our solar
system may require special conditions for them to acquire and maintain their
more stable circular orbits.
"For the first time we have enough extrasolar planets out there to do some
comparative study. We have the statistical basis for starting to consider
how our solar system compares with other planetary systems," said astronomer
Geoffrey Marcy, University Distinguished Professor of Science at San
Francisco State University. "We are realizing that most of the Jupiter-like
planets far from their stars tool around in elliptical orbits, not circular
orbits, which are the rule in our solar system."
Marcy, a member of the most prolific team of extrasolar planet discoverers,
presented this emerging trend in a press conference today at a meeting of
the American Astronomical Society in Austin, Texas. He is the lead author of
a paper describing the conclusions that has been submitted for publication
to the Astrophysical Journal.
Among the nine planets with elliptical orbits is a new discovery. This
planet orbits the star HD168443 in the constellation Serpens, the Snake. It
was detected during observations with the world's largest telescope at the
W.M. Keck Observatory atop Mauna Kea on the island of Hawaii.
The new planet has an orbital period of 58 days and orbits at an average
distance of 0.28 Astronomical Units from its star (one A.U. equals the mean
distance from the Earth to the Sun). The eccentricity of its orbit -- the
degree that it deviates from a circular path -- is 0.54, about ten times the
eccentricity in the orbit of Saturn. The other eight extrasolar planets that
orbit farther than 0.2 A.U. from their host stars all have orbital
eccentricities greater than 0.1.
...
From: Jean.Schneider@obspm.fr
Date: Mon, 12 Oct 1998 13:13:44 +0002
Subject: two more extrasolar planets
To: exoplanets@gagax5.obs.ujf-grenoble.fr
Two planets around HD 195019 and HD 217107
More details on
http://www.obspm.fr/planets (Europe)
http://cfa-www.harvard.edu (USA)
Jean Schneider
Observatoire de Paris
From: Andrew Yee
Subject: Two more planets discovered beyond our solar system (Forwarded)
Date: Thu, 24 Sep 1998 01:27:45 GMT
Two more planets discovered beyond our solar system
San Francisco State University-based planet search has found nine of 12
extrasolar planets detected since 1995
SAN FRANCISCO, CA, September 24, 1998 -- Deploying the massive Keck
telescope in Hawaii in a new planet search, a team of astronomers has
detected two planets orbiting Sun-like stars, bringing to 12 the number of
distant worlds discovered beyond our solar system.
One of the new discoveries, a Jupiter-sized sphere that most likely appears
deep blue-violet, barely skims the outer reaches of its yellow star, passing
25 times closer to the star than the Earth's orbit of the Sun, and nine time
closer than Mercury's path around the Sun. Its close orbit allows it to
circle its star about every three days. In contrast, the other new planet
has a more Earth-like orbit. Its average distance from its star is nearly
the same as the Earth-Sun distance, the first planet discovered with such a
familiar distance. A year on this planet is 437 days.
"We had discovered planets that orbit much closer and much farther from
their stars than the Earth-Sun distance," said Geoffrey Marcy, University
Distinguished Professor of Science at San Francisco State University who,
along with Paul Butler of the Anglo-American Observatory, has discovered
nine of the dozen planets so far detected.
"We wondered if nature rarely puts planets at one Earth-Sun distance," Marcy
continued. "Now we know that such planets are not rare." Marcy also holds a
post as adjunct professor of astronomy at UC Berkeley.
A report on the planet with the small orbit (around star HD187123) has been
accepted by Publications of the Astronomical Society of the Pacific. The
paper on the planet with the more Earth-like orbit (around star HD210277)
will be submitted to the Astrophysical Journal Letters. Co-authors with
Marcy and Butler on both papers, and colleagues in the SF State-based
discovery team, are Steve Vogt, professor of astronomy at the University of
California, Santa Cruz, who developed the spectrometer needed for planet
detection; Debra Fischer, post-doctoral researcher with Marcy at SF State;
and Kevin Apps, an undergraduate at the University of Sussex.
Apps, a sophomore in physics and astrophysics at Sussex and an amateur
astronomer since the age of seven, is intensely interested in the likelihood
of planets around Sun-like stars. In 1997, he e-mailed Marcy and Butler,
asking if he could see their list of candidate stars in the new planet
search they were launching at the Keck Observatory in Mauna Kea, the world's
largest telescope for optical and infrared astronomy. Upon analyzing the
stars' temperature, luminosity, composition and other features using new
satellite data available on the Internet, Apps discovered that 30 of the
stars were actually not good candidates, and he offered to supply a list of
30 "solar ringers," as he calls them, in their place.
To his surprise, Marcy and Butler agreed to substitute 30 candidate stars
with Apps' 30 solar ringers. One of the newly discovered planets orbits a
star -- HD187123 -- from Apps' list.
"I don't think I can put into words how I feel about Geoff and Paul finding
a planet around one of my suggested targets," says Apps.
Marcy is quite impressed with the young amateur. "He used the latest
satellite data, sifted out the stars that would have the best likelihood of
harboring planets. He shows a fierce interest in this research. It's great
to have him as a colleague."
The two discoveries are among 430 candidates in the new planet search using
the Keck Observatory. The observations were made over 12 nights during the
last nine months, under the auspices of NASA and the University of
California.
Marcy expects to discover "something like" two dozen Jupiter-sized planets
orbiting stars within one Earth-Sun distance. "That should happen within the
next three years if the law of averages applies," he says.
But a second goal of the planet search is to discover Jupiters much farther
out from their stars -- "like five Earth-Sun distances: the signposts of solar
systems like ours," Marcy adds. "Make no mistake about it," he says. "What
we're all about is discovering (planets) where evolution might have gotten a
toehold. Jupiter-sized planets at a greater distance from their star would
suggest a solar system that could host a rocky Earth-like planet. And if it
should turn out that out of more than 400 stars, none has a Jupiter orbiting
at five Earth-Sun distances, that would be a frightening reality. It might
be the first sign that Earth is truly unusual and so life may be rare."
The planets were discovered by detecting a characteristic wobble in the
motion of the star, a wobble caused by the gravitational effect of the
planet orbiting the star. The detection was made using the HIRES
spectrometer built by Steven Vogt and deployed on the Keck telescope.
HD 187123, the star with the close orbiting planet, is a near twin of the
Sun. This star is 154 light years (48 parsecs) away in the constellation
Cygnus (the Swan). The star has the same size, mass, temperature and
luminosity as the Sun, but is richer in heavy elements such as iron. Almost
all planets found to date orbit stars that are at least as rich in heavy
elements as the Sun. This trend toward heavy elements, Marcy says, may be a
clue about how planets form.
The planet is closer to its host star than any planet found before. It
orbits only 0.042 AU away from its sun. (An AU is the Earth-Sun distance).
Indeed, it orbits only four stellar diameters from the surface of the star
HD187123. Its period is 3.097 days.
HD210277, the star with the planet that has the Earth-like orbit, is slightly
bigger than the Sun. It is 68 light years (21 parsecs) away, in the direction
of the constellation Aquarius. The planet has an average orbital distance
barely greater (15 percent) than that of the Earth's. Until now, the
extrasolar planet that had been closest to an orbit the size of Earth's was
16 Cygni B, with an average distance 70 percent greater than Earth's. The
planet is about the size of Jupiter.
The technical paper and graphs on the discovery of HD187123 can be viewed
at: http://cannon.sfsu.edu/~gmarcy/planetsearch/papers.html
Further information on the planet search is available at:
http://www.physics.sfsu.edu/~gmarcy/planetsearch/planetsearch.html
From: Fabien Malbet
Date: Wed, 1 Jul 1998 18:20:45 +0200 (DFT)
To: "List 'Exoplanets'"
Subject: 2 new exoplanets
From: TEICHMANN Elisabeth
----------------------------------------------------------------------
1) A NEW EXTRASOLAR PLANET DISCOVERED AT THE HAUTE PROVENCE
OBSERVATORY
(Not to be released before the 6th of July 1998)
In 1995 the discovery of a planet in orbit around the star 51 Pegasi, an almost
perfect twin of our Sun, astonished astronomers. A very strange planet with a
period as short as 4.23 days. This first discovery has subsequently been
followed by a fascinating series of new discoveries: planets with quite
diverse orbits, with periods ranging from 3.3 days to 1100 days, sometimes of
circular shape, sometimes very elongated. These discoveries have revealed to
astrophysicists the broad diversity of planetary systems around other stars.
If our own planetary system has giant planets only in its most remote external
regions, this is far from being the general rule.
Let us describe our recent discovery:
A GIANT PLANET WITH A LONG PERIOD
14 Herculis (Gliese 614) is a star somewhat less massive than our Sun (its mass
is only 80% that of our Sun) and lies at a distance of 60 light-years as
derived from the very precise HIPPARCOS astrometric satellite parallax.
We have carefully measured 14 Herculis since 1994 at the Haute-Provence
Observatory. These measurements have been done with the ELODIE spectrograph
mounted on the 1.93 meter telescope. This summer, after more than four years of
monitoring, the planet has completed its revolution around 14 Herculis.
This planet has a slightly elongated orbit of 4.4 years. Its mass is about 3.3
times that of Jupiter and it is at a distance of 2.5 AU (1 AU is the Earth-Sun
distance) from 14 Her.
This is the planetary orbit with the longest period among the presently
discovered extrasolar planets. Nevertheless, this giant planet is still twice
as close to 14 Her as Jupiter is to our Sun.
This long-period planet, orbiting a nearby star, is a very promising
candidate for direct imaging. The longer the period, the larger the separation
between the planet and the parent star, therefore the easier it becomes to
distinguish the feeble glow of the planet near the bright glare of the star.
The predicted separation between the planet and 14 Her is 0.14 arcsec,
sufficient to make us try its detection with the adaptive optics system of the
CFHT 3.60m at the summit of Mauna Kea in Hawaii. Despite the high quality
of the images obtained no companion could be detected: we are not dealing
with a star or a brown dwarf orbiting in a plane almost perpendicular to the
line-of-sight, but with a planet indeed. We will have to wait for the
future availability of new instruments to obtain an image of the planet.
The content in heavy chemical elements of 14 Her is rather large compared to
that of the Sun. This discovery reinforces the suggestion that giant planets
are more frequently observed around metal-rich stars. Heavy chemical elements
are needed to form dust or ice particles, and then by agglomeration,
planetesimals and the cores of giant planets. If the quantity of dust is large
enough, this is certainly a factor in favor of the formation of giant
planets.
This planet has been discovered at the Haute-Provence Observatory (France)
by a team of astronomers from Switzerland and France (Michel Mayor (1),
Didier Queloz (1,2), Jean-Luc Beuzit (3), Jean-Marie Mariotti (4),
Dominique Naef (1), Christian Perrier (5), Jean-Pierre Sivan (6)).
(1) Geneva Observatory, Switzerland
(2) JPL, Los Angeles, USA
(3) CFHT, Hawaii, USA
(4) ESO, Munich, Germany
(5) Grenoble Observatory, France
(6) Haute-Provence Observatory, France
Newsgroups: sci.astro
From: Andrew Yee
Subject: Astronomers find a planet orbiting one of the closest stars to Earth
Date: Sat, 27 Jun 1998 21:53:28 GMT
Science News
Washington, D.C.
Astronomers find a planet orbiting one of the closest stars to Earth
Two teams of astronomers this week reported that one of the sun's nearest
neighbors -- a star just 15 light-years from Earth -- possesses a planet 1.6
times as massive as Jupiter. The finding is reported in the June 27 issue of
Science News, a weekly news magazine.
As with other planets recently discovered, this object was not imaged, but
betrayed its presence through its gravitational tug on its parent star. A
leader of one of the teams, Geoffrey W. Marcy of San Francisco State
University and the University of California, Berkeley, reported the finding
on June 22 at a symposium of the International Astronomical Union in
Victoria, British Columbia. Marcy and his colleagues used telescopes at Lick
Observatory and the Keck I telescope atop Hawaii's Mauna Kea to detect a
telltale wobble in the motion of the nearby star Gliese 876. Just 2 hours
after his presentation, a colleague presented him with an e-mail from a team
led by Xavier Delfosse of Geneva and Grenbole observatories. The message
said that the team had confirmed the finding. These astronomers used
telescopes at the Haute-Provence Observatory in France and the European
Southern Observatory in La Serena, Chile. Details about the planet, which
has some intriguing properties, appear in the June 27 issue of Science News.
A copy of that story, by Ron Cowen, is attached. [Not attached ...
see below] Please credit Science News for the information. Geoffrey
Marcy's e-mail is gmarcy@etoile.berkeley.edu. Xavier Delfosse is
currently observing at the European Southern Observatory in La Serena,
Chile. His e-mail is xavier.delfosse@obs.unige.ch
Newsgroups: sci.astro
From: Andrew Yee
Subject: Astronomers Discover Mysterious Group of Newly Formed Stars Near Earth -- And a Brown Dwarf Companion (Forwarded)
Organization: UTCC Campus Access
Date: Tue, 9 Jun 1998 04:06:15 GMT
University of California-Los Angeles
Contact: Stuart Wolpert
stuartw@college.ucla.edu (310) 206-0511
Date: June 5, 1998
Astronomers Discover Mysterious Group of Newly Formed Stars Near Earth -- And
a Brown Dwarf Companion
UCLA astronomers announced today the discovery of very young stars in a most
unusual cluster close to the Earth. In addition, the astronomers -- UCLA
graduate student Richard Webb; Benjamin Zuckerman, UCLA professor of physics
and astronomy; and colleagues -- have found a giant planet, or "brown dwarf,"
with about 20 times the mass of Jupiter orbiting around one of the young stars.
Webb is presenting the findings at the American Astronomical Society meeting
in San Diego.
...
Another surprise is the brown dwarf -- a celestial object larger than a planet
but not quite a star. Seeing one near a bright star is like "trying to pick out
a firefly buzzing around a searchlight," Zuckerman said. Astronomers have been
searching for brown dwarfs for years, but have photographed very few (this one
is only the third) in orbit around a star.
How did the astronomers find it?
They detected a very faint, cool object located right next to a star that goes
by the name of CoD-33 7795. The cool object had not been seen previously
because of the bright glare from the star. The astronomers used a technique
known as "speckle imaging," which enabled them to reduce the glare. They said
it is likely that the cool object is a giant planet or brown dwarf about 20
times the mass of Jupiter.
The object is moderately far from the star -- about 100 times the distance
between the Earth and the Sun. Few things in astronomy are certain, and there
is a remote possibility that the cool object is merely a foreground or
background object, but the astronomers doubt that. If it is verified to be a
companion to CoD-33 7795, then it will likely be the lowest mass object
orbiting a star, other than the Sun, ever directly imaged through a telescope.
...
In addition, they have determined that HR 4796, a star that received
substantial attention in April, is also a member of this cluster. HR 4796 has
a disk of dusty material around it that astronomers suspect contains
coalescing planets. Other stars in the cluster, because of their youth, are
also strong candidates to have disks containing planets in formation,
Zuckerman and Webb believe.
With no cold molecular cloud to point the way, Webb and his colleagues instead
relied on the fact that young stars usually emit abundant X-rays to target
potential members of the cluster -- called the TW Hydrae Association, after
the first member to be discovered, the variable star TW Hydrae. The
astronomers studied an immense region of space, mostly in the southern
constellation of Hydra. In addition to using X-ray emission, the research team
used other techniques, including an analysis of the motion of the stars across
the sky, to narrow down a list of some 350 X-ray emitters to about 50
candidates that warranted further study. Among these 50 were found the new
cluster members.
The nearest young stars that astronomers typically study are about 450-500
light years from Earth. The 19 known stars and the brown dwarf in the TW Hya
Association, by contrast, are about three times closer. Many stars in the sky
are even closer to us than this, but all are much older.
The team's findings are based mainly on data obtained with the Low Resolution
Imaging Spectrometer on the 10-meter (400-inch) Keck II telescope at the Mauna
Kea Observatory in Hawaii. In addition, the researchers used data from the
Infrared Telescope Facility, also at Mauna Kea, Germany's Roentgen X-ray
Satellite and the Southern Proper Motion database archives maintained by Yale
University.
...
The research team -- which also includes Imants Platis, a postdoctoral scholar
at Yale; and UCLA graduate students Jennifer Patience, Michael Schwartz, and
Russel White -- will continue to study the cluster and its mysterious origin.
"We've found quite a few of the stars in the cluster, but there are more --
maybe a lot more," Webb commented.
From: "Roger Herzler"
Newsgroups: sci.astro,sci.astro.amateur
Subject: Hubble images extra-solar planets!
Date: Thu, 28 May 1998 10:35:43 -0700
From http://cnn.com/TECH/space/9805/27/hubble.planet/
----------------------------------------------------------------------------
NASA to unveil image of a planet in another solar system
Hubble Space Telescope
May 27, 1998
Web posted at: 10:21 p.m. EDT (0221 GMT)
WASHINGTON (CNN) -- The Hubble Space Telescope has captured the first actual
image of a planet outside our own solar system, NASA said Wednesday.
The picture will be debuted at a press conference scheduled for 1 p.m. EDT
Thursday at the National Aeronautics and Space Administration headquarters
in Washington.
NASA says the image shows a planet that is 2-to-3 times the mass of the
Jupiter and is located near a newly-forming binary star system. Such a
systems consists of two stars very close together and orbiting each other.
NASA says the finding has to be further substantiated and confirmed, but if
it all holds up this will be the most important discovery to date made by
the Hubble Space Telescope.
Astronomers first discovered extra-solar planets several years ago, but the
evidence of them was indirect. Astronomers couldn't see the planets
themselves, but concluded they were there because a planet's gravitational
pull can make the star it orbits wobble.
The image to be unveiled Thursday will be the first of an actual extra-solar
planet.
Newsgroups: sci.astro
From: Andrew Yee
Subject: New extra-solar planet discovered (Forwarded)
Date: Tue, 29 Apr 1997 19:42:09 GMT
April 24, 1997
NEW EXTRA-SOLAR PLANET DISCOVERED; CIRCULAR ORBIT SUGGESTS
IT FORMED LIKE PLANETS IN OUR SOLAR SYSTEM
CAMBRIDGE, MA -- The notion that giant, Jupiter-like bodies may be a common
occurrence around stars like the Sun has been bolstered by the discovery of
such an object orbiting Rho Coronae Borealis, a star in the constellation
Northern Crown. The newly discovered planet offers additional evidence for
how such systems form, and bolsters the idea that other worlds like our own
may be widespread throughout the galaxy.
...
With the AFOE capable of measuring velocity variations smaller than 10
meters per second (about 22 miles per hour), the scientists found that the
speed of Rho Coronae Borealis varied back and forth by about 67 meters per
second, or 150 miles per hour, over a 40-day period. This led the team to
conclude that the star has a companion in a 40-day orbit and, from the size
of the velocity variation and the mass of the star (almost identical to the
Sun), they calculated that the companion must be slightly more massive than
the planet Jupiter.
The short orbital period means the planet must lie only about 1/4 of an
Astronomical Unit from the star -- closer than Mercury orbits the Sun (an AU
is the distance of the Earth from the Sun). This also implies its
temperature would be about 300 degrees C, or more than 500 degrees F --
much too hot for liquid water to exist, and hence not a likely place for life
to form.
According to the researchers, the circular nature of the orbit suggests that
the planet was formed like the planets in our own solar system, that is,
through the slow coalescence of dust and gas from the circularly rotating
disk that is thought to surround all newborn stars. A more eccentric, or
highly elliptical orbit, could imply that the companion object was a failed
star, the unsuccessful second partner in a potential binary star system.
Subject: New Extra Solar Planet
From: cjones@gladstone.uoregon.edu (Christopher Michael Jones)
Date: 1996/10/23
Newsgroups: sci.astro.amateur
I just looked at the SFSU PlanetSearch page and they have published info
about the new planet they discovered (with UTexas [Cochran and Hatzes).
The new planet is around 16 Cygni and was discovered by UTexas and SFSU
independently. It has the highest eccentricity of any planet yet
(including in our solar system), e=0.65. The planet has an orbital
period of 2.2 years and has a mass of at least 1.55 Jupiters. Based on
assumptions of 16 Cygni's mass (the star) the planet's orbit ranges from
a distance of .6 AU (about at Venus) to 2.7 AU (beyond Mars) from 16
Cygni. On the site, they've even updated the graphs of all the
planets (the comparison of solar systems and the mass histogram).
However, as far as I know, they haven't provided any info about the
possibility of a second planet around 55 Cancri.
So, by my count, the SFSU team has discovered a total of (drumroll
please) 7 new planets (not including the as yet unpublished report of a
secondary planet around 55 Cancri). And, out of the total 120 stars that
they have been monitoring, 8 of those stars have yielded planets that
could be detected by their equipment (although they probably have other
planets and unsure detections that they haven't told us about.) From a
very crude estimate that means that for main sequence sun-like stars,
there is about an 8/120 or 1/15 chance that they will have planets that
can be detected with current equipment. This means that if they were
to study 1000 stars, they would _detect_ planets around about 67 of those
stars. Pretty cool huh?
BTW, the website is
http://cannon.sfsu.edu/~williams/planetsearch/planetsearch.html
Subject: Yet Another New Planet from SFSU
From: calst40+@pitt.edu (Carole Lepilleur)
Date: 1996/07/11
Newsgroups: sci.astro,sci.astro.amateur
Yep, looks like the Marcy and Butler team have bagged another one.
According to the Extrasolar Planets Encyclopedia web site:
Star: Upsilon Andromeda {HR458,HD9826} (F7V) distance: ~ 16.5 pc
Object Mass: 0.6 Mjupiter
Distance from primary: 0.04 AU
Orbital Period: 4.6 Days
This (I think) is the 5th extrasolar planet found by this team.
for more info check their website:
http://cannon.sfsu.edu/~williams/planetsearch/planetsearch.html
Wednesday, June 12, 1996
Signs of a New Planet Near Earth
Initial observations suggest another solar system may exist
By Curt Suplee
Washington Post
Astronomers have found preliminary evidence of a
Jupiter-size planet - and perhaps an entire planetary system-
that is much closer to Earth than any previously detected and
that may be surprisingly similar to our own solar system.
The announcement, made yesterday, prompted a spectrum of
responses. "It's fantastic," said Alan P. Boss, an astro-
physicist at Carnegie Institution of Washington. "This is
the one we've really been waiting for."
Others were more cautious. "It's an interesting report
that requires confirmation," said Stephen P. Maran, spokesman
for the American Astronomical Society (AAS). "This is one
where many astronomers are being particularly careful."
One reason is that the observational stakes are sky-high:
Discovery of planets similar to those around the Sun would
be an epochal event. As recently as 1994, astronomers had
certain knowledge of only one planetary system in the cosmos -
our own. Since then, they have detected several super-big
gaseous planets around other stars, but with masses so enormous
or orbits so small or elliptical that they bear little resemblance
to the solar system.
The new observations indicate a Jupiter-sized object in a
circular orbit at about the same distance from its star that Saturn
is from the sun, and suggest that as many as two other planets
may be in orbit around the small red star called Lalande 21185,
the fourth-closest star to Earth.
The discovery, made by George Gatewood and colleagues at the
University of Pittsburgh's Allegheny Observatory, was reported
yesterday at a meeting of the AAS in Madison, Wis. For 66 years,
Allegheny's telescope has been tracking Lalande 21185, which is one
of the most intensely studied objects in the sky because it is only
8.1 light-years from Earth - just around the corner in astronomical
terms. (One light-year is about 6 trillion miles. The nearest star
to Earth is Proxima Centauri, about 4.2 light-years away.)
From: Eric Williams
Newsgroups: sci.astro,sci.astro.amateur,alt.sci.planetary
Subject: Yet another new extrasolar planet from SFSU
Date: Wed, 12 Jun 1996 11:22:57 -0700
The San Francisco State University planetsearch team has put another
extrasolar planet on their website. Come on over and check it out!!
See my address below.
This one is similar to 51 Peg and 55 Cancri:
P = 3.3128 days!
K = 468 m/s
semi-major axis = 0.0462 AU
circular orbit.
inferrred Msini = 3.86 Jupiter masses, much large than 51 Peg and 55 Cancri.
The star is HR5185 (tau Boo):
Distance to star is 19 parsecs
F7V
And the star is photometrically stable to the milli-mag level!
Wild stuff!!
--
Eric Williams - planet hunter
williams@stars.sfsu.edu
http://cannon.sfsu.edu/~williams
From: rmcrutch@vela.acs.oakland.edu (rmcrutch)
Newsgroups: sci.astro
Subject: Discovery of New Extra Solar Planet
Date: 13 Apr 1996 17:05:35 GMT
Dr. Geoff Marcy and Dr. Paul Butler have discovered another extrasolar
planet orbiting a star similar to the sun.
See http://cannon.sfsu.edu/~williams/planetsearch/planetsearch.html
The star is HR 3522 also designated HD 75732 and 55 Cancri
The star is classified as type G8V.
RA 08 52 35.8 DEC + 28 19 51 epoch 2000.
The distance of the star from earth is 14 Parsecs or
45 light years according to Sky Cataloque 2000.0.
The mass of the planet is estimated at 0.8 Jupiter masses.
The orbital period of the planet is 14.76 days.
The amplitude of the observed motion is 72 M/S.
The star is located in the constellation Cancer.
Subject: Re: Planet discovered at HD114762
From: wdc@shiraz.as.utexas.edu (William Cochran)
Date: 1996/02/10
Message-ID: <4fhlhi$t8l@geraldo.cc.utexas.edu>
Newsgroups: sci.astro,sci.astro.amateur
[More Headers]
[Subscribe to sci.astro]
In article <4fhgei$m08@ixnews3.ix.netcom.com>,
Duane Sand wrote:
>The planet-finding team of Marcy and Butler have done it again,
>discovering today the fourth known Jupiter-scale planet around nearby
>Sol-like stars. This one is around the star named HD 114762. It has
>an orbital period of 84 days, a presumed mass of about 9 Jupiters, and
>(if my notes are right) a very eccentric orbit like one of the prior
>discoveries.
>
I think you probably misinterpreted what Geoff Marcy said. The discovery
of a companion object to HD114762 was made in 1989 by David Latham, Tsevi
Mazeh, and Robert Stefanik. It was published in Nature, volume 339, 38,
1989. There has subsequently been a lot of follow-up work by several groups,
including both ours (Astrophysical Journal Letters, vol 380, L35, 1991)
and now by Marcy's group. This object is most likely a brown dwarf,
rather than a planet.
From http://www.seds.org/billa/tnp/other.html:
On 1/17/96 Geoffrey Marcy and Paul Butler announced the discovery of
planets orbiting the stars 70 Virginis and 47 Ursae Majoris. These were
discovered using the same doppler shift technique that found the planet
orbiting 51 Pegasi.
The planet around 70 Vir orbits the star in an eccentric, elongated
orbit every 116 days and has a mass about nine times that of Jupiter.
Using standard formulas that balance the sunlight absorbed and the heat
radiated, Marcy and Butler calculated the temperature of the planet at
about 85 degrees Celsius (185 degrees Fahrenheit), cool enough to
permit water and complex organic molecules to exist. The star 70 Vir is
nearly identical to the Sun, though several hundred degrees cooler and
perhaps three billion years older.
The planet around 47 UMa was discovered after analysis of eight years
of observations at Lick. Its period is a little over three years (1100
days), its mass about three times that of Jupiter, and its orbital
radius about twice the Earth's distance from the Sun. This planet too
probably has a region in its atmosphere where the temperature would
allow liquid water.
Newsgroups: sci.astro.amateur
Subject: Re: About the new planet thing!
From: galaxy@ccnet.com (Ken Croswell)
Date: 1995/10/22
Farzad (s944258@umslvma.umsle.du) wrote:
: I always thought that we already knew that there were other planets
: orbiting other suns. What is so special about this new planet that has
: been recently discovered?
51 Pegasi is a star similar to the Sun, so if it does have a
planet--and press reports notwithstanding, that is still an "if"--it is
the first planet discovered around a Sunlike star. The first planets
discovered outside the solar system were found by Aleksander Wolszczan
and Dale Frail in 1991 around the pulsar PSR B1257+12.
Ken Croswell
From: Mr Astro (mrastro@aol.com)
Subject: S&T's News Bulletin - Oct 13
This is the only article in this thread
View: Original Format
Newsgroups: sci.astro.amateur
Date: 1995/10/15
======================================================================
SKY & TELESCOPE'S NEWS BULLETIN -- OCTOBER 13, 1995
======================================================================
POSSIBLE PLANET IN PEGASUS
What may be the first discovery of a planet orbiting a normal, Sun-like
star other than our own has been announced by astronomers studying 51
Pegasi, a type G5 main-sequence star 42 light-years from Earth.
At a conference in Florence, Italy, last week, Michel Mayor and Didier
Queloz of Geneva Observatory explained that they observed 51 Pegasi with a
high-resolution spectrograph and found that the star's line-of-sight
velocity changes by some 70 meters per second every 4.2 days. If this is
due to orbital motion, these numbers suggest that a planet lies some 7
million kilometers from 51 Pegasi -- much closer than Mercury is to the
Sun -- and that the planet has a mass at least half that of Jupiter. These
physical characteristics hinge on the assumption that our line of sight is
near the planet's orbital plane. However, other evidence suggests that
this is a good bet.
A world merely 7 million km from a star like 51 Pegasi should have a
temperature of about 1,000 degrees Celsius, just short of red hot.
Probably lacking an atmosphere, the planet may be a ball of iron and rock
with seven times the Earth's diameter and seven times its surface gravity.
One side may permanently face the star, much as the Moon's does the Earth.
Such scenarios remain speculative, however, until 51 Pegasi's velocity
variations are confirmed and alternate explanations, such as simple
pulsation, are ruled out. Other astronomers are racing to confirm the
discovery. The only other planets known to lie beyond our solar system are
two Earth-size bodies (and a possible moon) orbiting a pulsar in Virgo.
The 5.5-magnitude 51 Pegasi is easily visible in binoculars, high in the
evening sky, between Alpha and Beta Pegasi, the western pair of stars in
the Great Square of Pegasus. The star's equinox-2000 coordinates are R.A.
22 hours 57 minutes, Dec. +20 degrees 46 minutes.
Newsgroups: sci.astro.amateur
Subject: 51 Pegasi: Jovian sighted?
From: ad696@FreeNet.Carleton.CA (Dwight Williams)
Date: 1995/10/08
I just read newspaper accounts of a Jupiter-type world that
has apparently been found orbiting 51 Pegasi.
Does anyone have any additional info on the subject?
An intertested layperson...
--
Dwight Williams(ad696@freenet.carleton.ca) -- Orleans, Ontario, Canada