SETI public: 3 papers

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Paper: astro-ph/0512450
Date: Fri, 16 Dec 2005 21:51:54 GMT (12kb)

Title: The Origins of the Substellar Companion to GQ Lup

Authors: J.H. Debes, S. Sigurdsson

Comments: 6 pages, submitted to A&A
\\
The recently discovered substellar companion to GQ Lup possibly represents a
direct test of current planet formation theories.

We examine the possible formation scenarios for the companion to GQ Lup
assuming it is a $\sim$2 M$_{Jup}$ object. We determine that GQ Lup B most
likely was scattered into a large, eccentric orbit by an interaction with
another planet in the inner system.

If this is the case, several directly observable predictions can be made,
including the presence of a more massive, secondary companion that could be
detected through astrometry, radial velocity measurements, or scuplting in
GQ
Lup's circumstellar disk. This scenario requires a highly eccentric orbit
for
the companion already detected. These predictions can be tested within the
next
decade or so. Additionally, we look at scenarios of formation if the
companion
is a brown dwarf. One possible formation scenario may involve an interaction
between a brown dwarf binary and GQ Lup. We look for evidence of any brown
dwarfs that have been ejected from the GQ Lup system by searching the 2MASS
all-sky survey.

\\ ( http://arXiv.org/abs/astro-ph/0512450 , 12kb)

Paper: astro-ph/0512477
Date: Mon, 19 Dec 2005 16:42:35 GMT (21kb)

Title: Gas Giant Protoplanets Formed by Disk Instability in Binary Star
Systems

Authors: A. P. Boss

Comments: 52 pages, 28 figures

Journal-ref: Astrophysical Journal, vol. 641, 20 April 2006 issue
\\
We present a suite of three dimensional radiative gravitational
hydrodynamics
models suggesting that binary stars may be quite capable of forming
planetary
systems similar to our own. The new models with binary companions do not
employ
any explicit artificial viscosity, and also include the third (vertical)
dimension in the hydrodynamic calculations, allowing for transient phases of
convective cooling. The calculations of the evolution of initially
marginally
gravitationally stable disks show that the presence of a binary star
companion
may actually help to trigger the formation of dense clumps that could become
giant planets. We also show that in models without binary companions, which
begin their evolution as gravitationally stable disks, the disks evolve to
form
dense rings, which then break-up into self-gravitating clumps. These latter
models suggest that the evolution of any self-gravitating disk with
sufficient
mass to form gas giant planets is likely to lead to a period of disk
instability, even in the absence of a trigger such as a binary star
companion.

\\ ( http://arXiv.org/abs/astro-ph/0512477 , 21kb)

Paper: astro-ph/0512478
Date: Mon, 19 Dec 2005 16:44:05 GMT (62kb)

Title: A Keplerian Disk around the Herbig Ae star HD169142

Authors: A. Raman (1), M. Lisanti (1,2), D.J. Wilner (1), C. Qi (1), M.
Hogerheijde (3) ((1) Harvard-Smithsonian Center for Astrophysics, (2)
Stanford University Department of Physics, (3) Leiden Observatory)

Comments: 10 pages, 2 figures, accepted by AJ
\\
We present Submillimeter Array observations of the Herbig Ae star HD169142
in
1.3 millimeter continuum emission and 12CO J=2-1 line emission at 1.5
arcsecond
resolution that reveal a circumstellar disk. The continuum emission is
centered
on the star position and resolved, and provides a mass estimate of about
0.02
solar masses for the disk. The CO images show patterns in position and
velocity
that are well matched by a disk in Keplerian rotation with low inclination
to
the line-of-sight. We use radiative transfer calculations based on a flared,
passive disk model to constrain the disk parameters by comparison to the
spectral line emission. The derived disk radius is 235 AU, and the
inclination
is 13 degrees. The model also necessitates modest depletion of the CO
molecules, similar to that found in Keplerian disks around T Tauri stars.

\\ ( http://arXiv.org/abs/astro-ph/0512478 , 62kb)

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