SETI bioastro: 2 papers on transitting exoplanets

SETI bioastro: 2 papers on transitting exoplanets

From: LARRY KLAES <ljk4_at_msn.com>
Date: Wed Jul 05 2006 - 13:40:17 PDT
Message-ID: <BAY114-F4DE44A6DB4569E04F075F9C760@phx.gbl>

Astrophysics, abstract
astro-ph/0606758

From: Nuno C. Santos [view email]

Date: Fri, 30 Jun 2006 17:03:59 GMT (168kb)

Chemical abundances for the transiting planet host stars OGLE-TR-10, 56,
111, 113, 132 and TrES-1. Abundances in different galactic populations

Authors: N.C. Santos, A. Ecuvillon, G. Israelian, M. Mayor, C. Melo, D.
Queloz, S. Udry, J.P. Ribeiro, S. Jorge

Comments: Accepted for publication in Astronomy & Astrophysics (June 2006)

We used the UVES spectrograph (VLT-UT2 telescope) to obtain high-resolution
spectra of 6 stars hosting transiting planets, namely for OGLE-TR-10, 56,
111, 113, 132 and TrES-1. The spectra are now used to derive and discuss the
chemical abundances for C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co,
Ni, Cu and Zn. Abundances were derived in LTE, using 1-D plane-parallel
Kurucz model atmospheres. For S, Zn and Cu we used a spectral synthesis
procedure, while for the remaining cases the abundances were derived from
measurements of line-equivalent widths. The resulting abundances are
compared with those found for stars in the solar neighborhood. Distances and
galactic coordinates are estimated for the stars. We conclude that besides
being particularly metal-rich, with small possible exceptions OGLE-TR-10,
56, 111, 113, 132 and TrES-1 are chemically undistinguishable from the field
(thin disk) stars regarding their [X/Fe] abundances. This is particularly
relevant for the most distant of the targets, located at up to ~2 Kpc from
the Sun. We also did not find any correlation between the abundances and the
condensation temperature of the elements, an evidence that strong accretion
of planetary-like material, tentatively connected to planetary migration,
did not occur.

http://arxiv.org/abs/astro-ph/0606758

Astrophysics, abstract
astro-ph/0607014

From: Adam Burrows [view email]

Date: Sun, 2 Jul 2006 21:28:36 GMT (175kb)

Theory for the Secondary Eclipse Fluxes, Spectra, Atmospheres, and Light
Curves of Transiting Extrasolar Giant Planets

Authors: A. Burrows, D. Sudarsky, I. Hubeny

Comments: 14 figures, 7 text pages (in two-column emulateapj format);
Accepted to the Ap.J. June 26, 2006; Submitted April 29, 2006

We have created a general methodology for calculating the
wavelength-dependent light curves of close-in extrasolar giant planets
(EGPs) as they traverse their orbits. Focussing on the transiting EGPs
HD189733b, TrES-1, and HD209458b, we calculate planet/star flux ratios
during secondary eclipse and compare them with the Spitzer data points
obtained so far in the mid-infrared. We introduce a simple parametrization
for the redistribution of heat to the planet's nightside, derive constraints
on this parameter (P_n), and provide a general set of predictions for
planet/star contrast ratios as a function of wavelength, model, and phase.
Moreover, we calculate average dayside and nightside atmospheric
temperature/pressure profiles for each transiting planet/P_n pair with which
existing and anticipated Spitzer data can be used to probe the atmospheric
thermal structure of severely irradiated EGPs. We find that the baseline
models do a good job of fitting the current secondary eclipse dataset, but
that the Spitzer error bars are not yet small enough to discriminate cleanly
between all the various possibilities.

http://arxiv.org/abs/astro-ph/0607014
Received on Wed Jul 5 13:44:47 2006

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