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Post Info TOPIC: HD 51106 and HD 50747
Blobrana


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HD 15407A
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 Subaru-Led Team Discovers a Rare Stellar Disk of Quartz Dust

A research team of Japanese astronomers led by Dr. Hideaki Fujiwara (Subaru Telescope) has discovered a main-sequence star that is surrounded by a rare disk of quartz dust. Collisions of planetesimals, building blocks for planets, may have produced the dusty quartz ring during planet formation around the star. Based on observations with the AKARI and Spitzer infrared space telescopes, this recently discovered, intriguing feature of a stellar system may open new doors for research on the mineralogical nature of extrasolar planetary systems.
The team discovered that the sun-like star HD 15407A, located in the Constellation Perseus 180 light years away from Earth, emits very bright infrared light relative to its visible light. Since HD 15407A is a main-sequence star, active collisions of planetesimals around it could produce a large amount of dust and emit infrared light.
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Blobrana


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Title: Silica-Rich Bright Debris Disk around HD 15407A
Authors: Hideaki Fujiwara, Takashi Onaka, Takuya Yamashėta, Daisuke Ishihara, Hirokazu Kataza, Misato Fukagawa, Yoichi Takeda, Hiroshi Murakami

We report an intriguing debris disk towards the F3V star HD 15407A, in which an extremely large amount of warm fine dust (~ 10^(-7) Earth masses) is detected. The dust temperature is derived as ~ 500-600 K and the location of the debris dust is estimated as 0.6-1.0 AU from the central star, a terrestrial planet region. The fractional luminosity of the debris disk is ~ 0.005, which is much larger than those predicted by steady-state models of the debris disk produced by planetesimal collisions. The mid-infrared spectrum obtained by Spitzer indicates the presence of abundant micron-sized silica dust, suggesting that the dust comes from the surface layer of differentiated large rocky bodies and might be trapped around the star.

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Blobrana


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Posts: 131433
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HD 51106 and HD 50747
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Title: HD 51106 and HD 50747: an ellipsoidal binary and a triple system observed with CoRoT
Authors: N. Dolez, S. Vauclair, E. Michel, A. Hui Bon Hua, G. Vauclair, D. Le Contel, P. Mathias, E. Poretti, P. J. Amado, M. Rainer, R. Samadi, A. Baglin, C. Catala, M. Auvergne, K. Uytterhoeven, J. C. Valtier

We present an analysis of the observations of HD 51106 and HD 50747 by the satellite CoRoT, obtained during its initial run, and of the spectroscopic preparatory observations.
AIMS: We complete an analysis of the light curve, extract the main frequencies observed, and discuss some preliminary interpretations about the stars.
Methods: We used standard Fourier transform and pre-whitening methods to extract information about the periodicities of the stars.
Results: HD 51106 is an ellipsoidal binary, the light curve of which can be completely explained by the tidal deformation of the star and smaller secondary effects. HD 50747 is a triple system containing a variable star, which exhibits many modes of oscillation with periods in the range of a few hours. On the basis of this period range and the analysis of the physical parameters of the star, we conclude that HD 50747 is a Gamma-Doradus star.

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