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TOPIC: GJ758
Blobrana


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Posts: 131433
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GJ 758 B
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Title: Project 1640 Observations of Brown Dwarf GJ 758 B
Author: R. Nilsson (1 and 2 and 3), A. Veicht (1), P. A. Giorla Godfrey (1 and 4 and 5), E. L. Rice (1 and 4 and 5), J. Aguilar (6), L. Pueyo (7), L. C. Roberts Jr. (8), R. Oppenheimer (1), D. Brenner (1), S. H. Luszcz-Cook (1), E. Bacchus (9), C. Beichman (11 and 1), R. Burruss (8), E. Cady (8), R. Dekany (10), R. Fergus (12), L. Hillenbrand (3), S. Hinkley (13), D. King (9), T. Lockhart (8), I. R. Parry (9), A. Sivaramakrishnan (7), R. Soummer (7), G. Vasisht (8), C. Zhai (8), N. T. Zimmerman (7) ((1) Astrophysics Department, American Museum of Natural History, New York, NY, USA, (2) Department of Astronomy, Stockholm University, Stockholm, Sweden, (3) Department of Astronomy, California Institute of Technology, Pasadena, CA, USA, (4) City University of New York, New York, NY, USA, (5) Department of Engineering Science & Physics, College of Staten Island, Staten Island, NY, USA, (6) Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, USA, (7) Space Telescope Science Institute, Baltimore, MD, USA, (8) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA, (9) Institute of Astronomy, Cambridge University, Cambridge, UK, (10) Caltech Optical Observatories, California Institute of Technology, Pasadena, CA, USA, (11) NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, CA, USA, (12) Department of Computer Science, Courant Institute of Mathematical Sciences, New York University, New York, NY, USA, (13) School of Physics, University of Exeter, Exeter, UK)

The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of \lesssim 30 AU, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion's physical characteristics, we acquired the first low-resolution (R~50) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory's 5-m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the Y, J, and H bands (~952-1770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with chiČ minimization suggesting a best fit for spectral type {T7.0±1.0}, but with a shallow minimum over T5-T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature {T_eff=741±25 K} and surface gravity {log g=4.3±0.5 dex} (cgs). Our derived best-fit spectral type and effective temperature from modelling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date.

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Blobrana


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Posts: 131433
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RE: GJ758
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Astronomers say they have taken the first direct image of a planet-like object orbiting a star much like our own sun.
A similar breakthrough was announced last year, when astronomers unveiled direct images of a single-planet and multiple-planet system. However, the host stars of such systems are stellar giants that are much more massive than the sun.
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Credit: Max Planck Institute for Astronomy/National Astronomical Observatory of Japan

This August 2009 discovery image of GJ 758 B was taken with the Subaru Telescope's HiCIAO instrument in the near infrared, which measures and records differences in heat. Without the special technique employed here (angular differential imaging), the star's glare would overwhelm the light from the planet candidates. The planet-like object, GJ 758 B, is circled as B in the lower right portion of the image. An unconfirmed companion planet or planet-like object, C, can be viewed above B. The star, GJ 758, is located at the center of the image, at the hub of the starburst. The graphic at the top compares the orbital distances of solar system planets.

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Blobrana


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Discovery of an Exoplanet Candidate Orbiting a Sun-Like Star: Inaugural Observations with Subaru's New Instrument HiCIAO
The first observations with the world's newest planet-hunting instrument on the Subaru Telescope, HiCIAO (High Contrast Instrument for the Subaru next generation Adaptive Optics), have revealed a companion to the Sun-like star GJ 758. With an estimated mass of 10-40 times Jupiter's mass, GJ 758 B is either a giant planet or a lightweight brown dwarf. Its projected orbit is comparable in size to Neptune's, and its temperature of 600 K makes it the coldest companion to a Sun-like star ever resolved in an image. A second companion with a similar mass at the Uranus's orbit is also possible, but not yet confirmed. This is the first clear detection of planet candidates around the Sun-like stars. The presence of such massive planets at these large distances challenges standard assumptions about planetary system formation based on the Solar System. Since the strategic search for exoplanets and their formation sites has just started at the Subaru Telescope, further research such as this will eventually answer whether the Solar System is ubiquitous or not.

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Blobrana


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Posts: 131433
Date:
GJ 758 B
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An international team of scientists that includes an astronomer from Princeton University has made the first direct observation of a planet-like object orbiting a star similar to the sun.
The finding marks the first discovery made with the world's newest planet-hunting instrument on the Hawaii-based Subaru Telescope and is the first fruit of a novel research collaboration announced by the University in January.
The object, known as GJ 758 B, could be either a large planet or a "failed star," also known as a brown dwarf. The faint companion to the sun-like star GJ 758 is estimated to be 10 to 40 times as massive as Jupiter and is a "near neighbor" in our Milky Way galaxy, hovering a mere 300 trillion miles from Earth.

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Blobrana


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Posts: 131433
Date:
GJ 758
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Title: Discovery of the Coldest Imaged Companion of a Sun-Like Star
Authors: Christian Thalmann (1), Joseph Carson (1 and 2), Markus Janson (3), Miwa Goto (1), Michael McElwain (4), Sebastian Egner (5), Markus Feldt (1), Jun Hashimoto (6), Yutaka Hayano (5), Thomas Henning (1), Klaus W. Hodapp (7), Ryo Kandori (6), Hubert Klahr (1), Tomoyuki Kudo (6), Nobuhiko Kusakabe (6), Christoph Mordasini (1), Jun-Ichi Morino (6), Hiroshi Suto (6), Ryuji Suzuki (5), Motohide Tamura (6) ((1) Max Planck Institute for Astronomy, (2) College of Charleston, (3) University of Toronto, (4) Princeton University, (5) Subaru Telescope, (6) National Astronomical Observatory of Japan, (7) Institute for Astronomy, University of Hawai`i)

We present the discovery of a brown dwarf or possible planet at a projected separation of 1.9" = 29 AU around the star GJ 758, placing it between the separations at which substellar companions are expected to form by core accretion (~5 AU) or direct gravitational collapse (typically >100 AU). The object was detected by direct imaging of its thermal glow with Subaru/HiCIAO. At 10-40 times the mass of Jupiter and a temperature of 550-640 K, GJ 758 B constitutes one of the few known T-type companions, and the coldest ever to be imaged in thermal light around a Sun-like star. Its orbit is likely eccentric and of a size comparable to Pluto's orbit, possibly as a result of gravitational scattering or outward migration. A candidate second companion is detected at 1.2" at one epoch.   

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Blobrana


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Posts: 131433
Date:
GJ758
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Astronomers have published an image of the coolest planet outside our solar system that has been pictured directly.
The new find is more similar to our own Solar System than prior pictured exoplanets, in terms of the parent star's type and the planet's size.
In two observations in May and August, an international team of researchers led by the Max Planck Institute for Astronomy focused the telescope on GJ758, a star about 50 light-years away.
They found a so-called gas giant planet of a mass somewhere between 10 and 40 times that of Jupiter, in an oval-shaped orbit around the star.
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Position(2000): RA 19 23 34, Dec  +33 13 19

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