# SETI public: A bunch of recent relevant papers

From: LARRY KLAES (ljk4_at_msn.com)
Date: Wed Dec 07 2005 - 07:58:04 PST

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Paper: astro-ph/0512091
Date: Mon, 5 Dec 2005 09:41:44 GMT (49kb)

Title: Birth and fate of hot-Neptune planets

Authors: I. Baraffe, Y. Alibert, G. Chabrier, W. Benz

Comments: 4 figures, accepted for publication in Astronomy and Astrophysics
\\
This paper presents a consistent description of the formation and the
subsequent evolution of gaseous planets, with special attention to
short-period, low-mass hot-Neptune planets characteristic of $\mu$ Ara-like
systems. We show that core accretion including migration and disk evolution
and
subsequent evolution taking into account irradiation and evaporation provide
a
viable formation mechanism for this type of strongly irradiated light
planets.
At an orbital distance $a \simeq$ 0.1 AU, this revised core accretion model
leads to the formation of planets with total masses ranging from $\sim$ 14
$\mearth$ (0.044 $\mjup$) to $\sim$ 400 $\mearth$ (1.25 $\mjup$). The newly
born planets have a dense core of $\sim$ 6 $\mearth$, independent of the
total
mass, and heavy element enrichments in the envelope, $M_{\rm Z,env}/M_{\rm env}$, varying from 10% to 80% from the largest to the smallest planets. We
examine
the dependence of the evolution of the born planet on the evaporation rate
due
to the incident XUV stellar flux. In order to reach a $\mu$ Ara-like mass
($\sim$ 14 $\mearth$) after $\sim$ 1 Gyr, the initial planet mass must
range
from 166 $\mearth$ ($\sim$ 0.52 $\mjup$) to about 20 $\mearth$, for
evaporation
rates varying by 2 orders of magnitude, corresponding to 90% to 20% mass
loss
during evolution. The presence of a core and heavy elements in the envelope
affects appreciably the structure and the evolution of the planet and yields
$\sim 8%-9%$ difference in radius compared to coreless objects of solar
composition for Saturn-mass planets. These combinations of evaporation rates
and internal compositions translate into different detection probabilities,
and
thus different statistical distributions for hot-Neptunes and hot-Jupiters.

\\ ( http://arXiv.org/abs/astro-ph/0512091 , 49kb)

Paper: astro-ph/0512092
Date: Mon, 5 Dec 2005 09:50:13 GMT (523kb)

Title: Analysis of ground-based differential imager performance

Authors: A. Boccaletti, D. Mouillet, T. Fusco, P. Baudoz C. Cavarroc, J.-L.
Beuzit, C. Moutou and K. Dohlen

Journal-ref: IAUC 200 proceedings, 2005
\\
In the context of extrasolar planet direct detection, we evaluated the
performance of differential imaging with ground-based telescopes. This study
was carried out in the framework of the VLT-Planet Finder project and is
further extended to the case of Extremely Large Telescopes. Our analysis is
providing critical specifications for future instruments mostly in terms of
phase aberrations but also regarding alignments of the instrument optics or
offset pointing on the coronagraph. It is found that Planet Finder projects
on
8m class telescopes can be successful at detecting Extrasolar Giant Planets
providing phase aberrations, alignments and pointing are accurately
controlled.
The situation is more pessimistic for the detection of terrestrial planets
with
Extremely Large Telescopes for which phase aberrations must be lowered at a
very challenging level.

\\ ( http://arXiv.org/abs/astro-ph/0512092 , 523kb)

Paper: astro-ph/0512105
Date: Mon, 5 Dec 2005 13:30:00 GMT (96kb)

Title: Multiplicity-Study of Exoplanet Host Stars

Authors: M. Mugrauer, R. Neuh\"auser, T.Mazeh, E. Guenther

\\
We carry out a systematic search campaign for wide companions of exoplanet
host stars to study their multiplicity and its influence on the long-term
stability and the orbital parameters of the exoplanets. We have already
found 6
wide companions, raising the number of confirmed binaries among the
exoplanet
host stars to 20 systems. We have also searched for wide companions of Gl86,
the first known exoplanet host star with a white dwarf companion. Our
Sofi/NTT
observations are sensitive to substellar companions with a minimum-mass of
35
Mjup and clearly rule out further stellar companions with projected
separations
between 40 and 670AU.

\\ ( http://arXiv.org/abs/astro-ph/0512105 , 96kb)

Paper: astro-ph/0512108
Date: Mon, 5 Dec 2005 14:21:16 GMT (116kb)

Title: The Space Interferometry Mission Astrometric Grid Giant-Star Survey.
I.
Stellar Parameters and Radial Velocity Variability

Authors: Dmitry Bizyaev (1,2), Verne V. Smith (1,3), Jose Arenas (4), Doug
Geisler (4), Steven R. Majewski (5), Richard J. Patterson (5), Katia Cunha
(1,6), Cecilia Del Pardo (7), Nicholas B. Suntzeff (8), Wolfgang Gieren (4)
((1) NOAO, (2) Sternberg Astronomical Institute, Russia, (3) McDonald
Observatory, UT Austin, (4)Universidad de Concepcion, Chile, (5) Univ. of
Virginia, (6)Observatorio Nacional, Brazil, (7) UTEP (8) CTIO, Chile)

Comments: Astronomical Journal, in press, 22 pages, 11 Postscript figures,
uses
aastex.cls
\\
We present results from a campaign of multiple epoch echelle spectroscopy of
relatively faint (V = 9.5-13.5 mag) red giants observed as potential
astrometric grid stars for the Space Interferometry Mission (SIM
PlanetQuest).
Data are analyzed for 775 stars selected from the Grid Giant Star Survey
spanning a wide range of effective temperatures (Teff), gravities and
metallicities. The spectra are used to determine these stellar parameters
and
to monitor radial velocity (RV) variability at the 100 m/s level. The degree
of
RV variation measured for 489 stars observed two or more times is explored
as a
function of the inferred stellar parameters. The percentage of radial
velocity
unstable stars is found to be very high -- about 2/3 of our sample. It is
found
that the fraction of RV-stable red giants (at the 100 m/s level) is higher
among stars with Teff \sim 4500 K, corresponding to the
calibration-independent
range of infrared colors 0.59 < (J-K_s)_0 < 0.73. A higher percentage of
RV-stable stars is found if the additional constraints of surface gravity
and
metallicity ranges 2.3< log g < 3.2 and -0.5 < [Fe/H] < -0.1, respectively,
are
applied. Selection of stars based on only photometric values of effective
temperature (4300 K < Teff < 4700 K) is a simple and effective way to
increase
the fraction of RV-stable stars. The optimal selection of RV-stable stars,
especially in the case when the Washington photometry is unavailable, can
rely
effectively on 2MASS colors constraint 0.59 < (J-K_s)_0 < 0.73. These
results
have important ramifications for the use of giant stars as astrometric
references for the SIM PlanetQuest.

\\ ( http://arXiv.org/abs/astro-ph/0512108 , 116kb)

Paper: astro-ph/0512150
Date: Tue, 6 Dec 2005 14:47:01 GMT (758kb)

Title: Dynamic tides in rotating objects: orbital circularisation of extra
solar planets for realistic planet models

Authors: P. B. Ivanov, J. C. B. Papaloizou

Comments: Submitted to MNRAS, resolution of several figures has been reduced
\\
(abbreviated) We consider the problem of the tidal capture or
circularisation
from large eccentricity of a uniformly rotating object. We extend the
self-adjoint formalism introduced in Papaloizou & Ivanov 2005 (PI) to derive
general expressions for the energy and angular momentum transfered when the
planet or a star passes through periastron in a parabolic or highly
eccentric
orbit around a central mass, without making a low frequency approximation as
was done in PI. We show how these can be adapted to the low frequency limit
in
which only inertial modes contribute to the energy and angular momentum
transfer. We calculate the inertial mode eigenspectrum for planet models of
one
and five Jupiter masses $M_J,$ without a solid core, with different radii
corresponding to different ages.

We consider the multi-passage problem when there is no dissipation finding
that stochastic instability resulting in the stochastic gain of inertial
mode
energy over many periastron passages occurs under similar conditions to
those
already found for the $f$ modes.

We apply our calculations to the problem of the tidal circularisation of the
orbits of the extra solar planets in a state of pseudo synchronisation, and
find that inertial mode excitation dominates the tidal interaction for $1 M_J$
planets that start with semi- major axes less than $10 AU$ and end up on
circular orbits with final period in the 4-6 day range. It is potentially
able
to account for initial circularisation up to a final 6 day period within a
few
$Gyr$ But in the case of $5M_J$ oscillation modes excited in the star are
more
important.

\\ ( http://arXiv.org/abs/astro-ph/0512150 , 766kb)

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