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TOPIC: Extrasolar Planets
Blobrana


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Posts: 131433
Date:
2MASS1207334-393243Ab
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Title: The First Direct Distance and Luminosity Determination for a Self-Luminous Giant Exoplanet: The Trigonometric Parallax to 2MASS1207334-393243Ab
Authors: Beth Biller, Laird Close (University of Arizona)
(Version v2)

We present the first trigonometric parallax and distance for a young planetary mass object. A likely TW Hya cluster member, 2MASS 1207Ab is an M8 brown dwarf with a mid to late L type planetary mass companion (Chauvin et al. 2004, Mohanty et al. 2007). Recent observations of spectral variability have uncovered clear signs of disk accretion and outflow, constraining the age of the system to <10 Myr. Because of its late spectral type and the clearly youthful nature of the system, 2MASS 1207b is definitely a planetary mass object. We have measured the first accurate distance (hence luminosity) for a self-luminous planetary mass object. Our parallax measurements are accurate to <2 mas (1sigma) for 2MASS 1207Ab. With 11 total epochs of data taken in 2006 and 2007, we determine a distance of 63 ±7.5 pc (15.8^{+2.1}_{-1.6} mas) to 2MASS 1207Ab and a luminosity of 8-23x10^-6 Lsun for 2MASS 1207b. Hence 2MASS 1207Ab is a clear member of the TW Hya cluster in terms of its distance, proper motions, and youthful nature.

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Position(2000): RA 12 07 33.4  Dec -39 32 54.0
Distance:  63 ±7.5 pc

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Blobrana


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Posts: 131433
Date:
TrES-4
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Scientists have discovered the universe's largest known planet, a giant ball made mostly of hydrogen that is 20 times bigger than Earth.
Scientists believe the planet, circling a star 1,400 light years away, is 1.7 times the diameter of Jupiter, the largest planet in our solar system, and has a temperature of 1,260C.

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Blobrana


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Posts: 131433
Date:
OGLE-2005-BLG-390Lb
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Exoplanet, OGLE-2005-BLG-390Lb, discovered  26000 Lys from earth. Most similar to earth than any other previous exoplanet observed. Announced Jan 2006.



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Blobrana


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Posts: 131433
Date:
TrES-4
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Title: TrES-4: A Transiting Hot Jupiter of Very Low Density
Authors: Georgi Mandushev, Francis T. O'Donovan, David Charbonneau, Guillermo Torres, David W. Latham, Gáspár Á. Bakos, Edward W. Dunham, Alessandro Sozzetti, José M. Fernández, Gilbert A. Esquerdo, Mark E. Everett, Timothy M. Brown, Markus Rabus, Juan A. Belmonte, Lynne A. Hillenbrand

We report the discovery of TrES-4, a hot Jupiter that transits the star GSC 02620-00648 every 3.55 days. From high-resolution spectroscopy of the star we estimate a stellar effective temperature of Teff = 6100 ± 150 K, and from high-precision z and B photometry of the transit we constrain the ratio of the semi-major axis and the stellar radius to be a/R = 6.03 ± 0.13. We compare these values to model stellar isochrones to constrain the stellar mass to be M* = 1.22 ± 0.17 Msun. Based on this estimate and the photometric time series, we constrain the stellar radius to be R* = 1.738 ± 0.092 Rsun and the planet radius to be Rp = 1.674 ± 0.094 RJup. We model our radial-velocity data assuming a circular orbit and find a planetary mass of 0.84 ± 0.10 MJup. Our radial-velocity observations rule out line-bisector variations that would indicate a specious detection resulting from a blend of an eclipsing binary system. TrES-4 has the largest radius and lowest density of any of the known transiting planets. It presents a challenge to current models of the physical structure of hot Jupiters, and indicates that the diversity of physical properties amongst the members of this class of exoplanets has yet to be fully explored.

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Blobrana


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An international team of astronomers has discovered the largest-radius and lowest-density exoplanet of all those whose mass and radius are known. It is a gas-giant planet about twice the size of Jupiter, and is likely to have a curved cometlike tail. It has been named TrES-4, to indicate that it is the fourth planet detected by the Trans-Atlantic Exoplanet Survey (TrES) network of telescopes.

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Blobrana


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Posts: 131433
Date:
Largest exoplanet
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An international team of astronomers has discovered the largest known planet orbiting another star.
The "transiting" planet - meaning one that passes in front of its parent star as seen from Earth - is about 70% larger than Jupiter.
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Blobrana


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Posts: 131433
Date:
TrES-4
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Astronomers at Lowell Observatory in Flagstaff have helped an international team of scientists discover TrES-4, the largest known planet outside our solar system, the observatory announced on Monday.
The Trans-Atlantic Exoplanet Survey said the planet is in the constellation of Hercules.
TrES-4 is about 1,400 light years away and orbits its host star, GSC 02620-00648, in three and a half days. Being only about 4.5 million miles from its home star, the planet is also extremely hot, about 2,300 degrees Fahrenheit.

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Blobrana


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Posts: 131433
Date:
Planet orbiting giant red star
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A planet orbiting a giant red star has been discovered by an astronomy team led by Penn State's Alex Wolszczan, who in 1992 discovered the first planets ever found outside this solar system. The new discovery is helping astronomers to understand what will happen to the planets in this solar system when the sun becomes a red-giant star, expanding so much that its surface will reach as far as Earth's orbit.

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Blobrana


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Posts: 131433
Date:
Planet Found Orbiting a Red Giant
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Title: A Planetary Mass Companion to the K0 Giant HD 17092.
Authors: A. Niedzielski, M. Konacki, A. Wolszczan, G. Nowak, G. Maciejewski, C. R. Gelino, M. Shao, M. Shetrone, L. W. Ramsey

We report the discovery of a substellar-mass companion to the K0-giant HD 17092 with the Hobby-Eberly Telescope. In the absence of any correlation of the observed 360-day periodicity with the standard indicators of stellar activity, the observed radial velocity variations are most plausibly explained in terms of a Keplerian motion of a planetary-mass body around the star. With the estimated stellar mass of 2.3 solar masses, the minimum mass of the planet is 4.6MJ. The planets orbit is characterised by a mild eccentricity of e=0.17 and a semi-major axis of 1.3 AU. This is the tenth published detection of a planetary companion around a red giant star. Such discoveries add to our understanding of planet formation around intermediate-mass stars and they provide dynamical information on the evolution of planetary systems around post-main sequence stars.

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Position(2000): RA = 02 46 22.1153 Dec = +49 39 11.063

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Blobrana


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Posts: 131433
Date:
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A planet outside our solar system with a year roughly equal to Earth's has been discovered around a dying, red giant star.
Only about 10 red giant stars are known to harbour planets; the new solar system is among the most distant of these.
Our sun will become a red giant in a few billion years, likely vaporising Earth.
The finding, to be detailed in the November issue of Astrophysical Journal, was made by a team led by Penn State astronomer Alex Wolszczan, who in 1992 discovered the first planets outside our solar system around a deadly, radiation-spewing star.
The new planet, spotted using the Hobby-Eberly Telescope at the McDonald Observatory in West Texas, circles its bloated parent star every 360 days and is located about 300 light-years away, in the constellation Perseus.

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