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TOPIC: LkCa 15

Blobrana

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Posts: 131433

Date: Nov 12 00:34 2011

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A Sydney astronomer has photographed the youngest planet ever discovered - a milestone that could help prove or challenge theories on how planets are born. The alien world was captured by Dr Michael Ireland as it was still forming from a giant disk of dust and gas around its parent star, The Daily Telegraph reported. Located about 450 light years away in the constellation Taurus, the newly forming planet called LkCa 15b is a relatively close neighbour to Earth. Read more __________________

Blobrana

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Posts: 131433

Date: Oct 23 22:00 2011

RE: LkCa 15	Permalink

UH Astronomer Finds Planet in the Process of Forming The first direct image of a planet in the process of forming around its star has been captured by University of Hawaii astronomer Adam Kraus. What astronomers are calling LkCa 15 b, looks like a hot "protoplanet" surrounded by a swath of cooler dust and gas, which is falling into the still-forming planet. Images have revealed that the forming planet sits inside a wide gap between the young parent star and an outer disk of dust. Read more __________________

Blobrana

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Posts: 131433

Date: Oct 19 15:29 2011

LkCa 15 b	Permalink

Youngest Planet Seen As Its Forming The first direct image of a planet in the process of forming around its star has been captured by astronomers who combined the power of the 10-meter Keck telescopes with a bit of optical sleight of hand. What astronomers are calling LkCa 15 b, looks like a hot "protoplanet" surrounded by a swath of cooler dust and gas, which is falling into the still-forming planet. Images have revealed that the forming planet sits inside a wide gap between the young parent star and an outer disk of dust. Read more __________________

Blobrana

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Posts: 131433

Date: Oct 19 04:13 2011

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Title: A Closer Look at the LkCa 15 Protoplanetary Disk Authors: Sean M. Andrews, Katherine A. Rosenfeld, David J. Wilner, Michael Bremer We present 870 micron observations of dust continuum emission from the LkCa 15 protoplanetary disk at high angular resolution (with a characteristic scale of 0.25" = 35 AU), obtained with the IRAM Plateau de Bure interferometer and supplemented by slightly lower resolution observations from the Submillimeter Array. We fit these data with simple morphological models to characterize the spectacular ring-like emission structure of this disk. Our analysis indicates that a small amount of 870 micron dust emission (~5 mJy) originates inside a large (40-50 AU radius) low optical depth cavity. This result can be interpreted either in the context of an abrupt decrease by a factor of ~5 in the radial distribution of millimetre-sized dust grains or as indirect evidence for a gap in the disk, in agreement with previous inferences from the unresolved infrared spectrum and scattered light images. A preliminary model focused on the latter possibility suggests the presence of a low-mass (planetary) companion, having properties commensurate with those inferred from the recent discovery of LkCa 15b. Read more (454kb, PDF) __________________

Blobrana

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Posts: 131433

Date: Oct 19 04:12 2011

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Title: LkCa 15: A Young Exoplanet Caught at Formation? Authors: Adam L. Kraus (Univ. of Hawaii - IfA), Michael J. Ireland (Macquarie University) Young and directly imaged exoplanets offer critical tests of planet-formation models that are not matched by RV surveys of mature stars. These targets have been extremely elusive to date, with no exoplanets younger than 10--20 Myr and only a handful of direct-imaged exoplanets at all ages. We report the direct imaging discovery of a likely (proto)planet around the young (~2 Myr) solar analog LkCa 15, located inside a known gap in the protoplanetary disk (a "transitional disk"). Our observations use non-redundant aperture masking interferometry at 3 epochs to reveal a faint and relatively blue point source (M_K'=9.1±0.2, K'-L'=0.98±0.22), flanked by approximately co-orbital emission that is red and resolved into at least two sources (M_L'=7.5±0.2, K'-L'=2.7±0.3; M_L'=7.4±0.2, K'-L'=1.94±0.16). We propose that the most likely geometry consists of a newly-formed (proto)planet that is surrounded by dusty material. The nominal estimated mass is ~6 M_{Jup} according to the 1 Myr hot-start models. However, we argue based on its luminosity, colour, and the presence of circumplanetary material that the planet has likely been caught at its epoch of assembly, and hence this mass is an upper limit due to its extreme youth and flux contributed by accretion. The projected separations (71.9 ±1.6 mas, 100.7 ±1.9 mas, and 88.2 ±1.8 mas) and deprojected orbital radii (16, 21, and 19 AU) correspond to the center of the disk gap, but are too close to the primary star for a circular orbit to account for the observed inner edge of the outer disk, so an alternate explanation (i.e., additional planets or an eccentric orbit) is likely required. This discovery is the first direct evidence that at least some transitional disks do indeed host newly-formed (or forming) exoplanetary systems, and the observed properties provide crucial insight into the gas giant formation process. Read more (243kb, PDF) __________________

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