SETI public: Hot Jupiters, Brown Dwarfs, and Sub-stellar Thingies in the Pleiades

• Previous message: LARRY KLAES: "SETI public: Papers on Circumstellar/Protoplanetary Disks"

Paper: astro-ph/0506468
Date: Mon, 20 Jun 2005 20:07:07 GMT (34kb)

Title: Obliquity Tides on Hot Jupiters

Authors: Joshua N. Winn and Matthew J. Holman (Harvard-Smithsonian Center
for
Astrophysics)
Comments: To appear in ApJ Letters [9 pages, 2 figures]
\\
Obliquity tides are a potentially important source of heat for extrasolar
planets on close-in orbits. Although tidal dissipation will usually reduce
the
obliquity to zero, a nonzero obliquity can persist if the planet is in a
Cassini state, a resonance between spin precession and orbital precession.
Obliquity tides might be the cause of the anomalously large size of the
transiting planet HD 209458b.

\\ ( http://arXiv.org/abs/astro-ph/0506468 , 34kb)

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Paper: astro-ph/0506485
Date: Tue, 21 Jun 2005 11:34:58 GMT (283kb)

Title: A resolved outflow of matter from a Brown Dwarf

Authors: Emma T. Whelan, Thomas P.Ray, Francesca Bacciotti, Antonella Natta,
Leonardo Testi, Sofia Randich
\\
The birth of stars involves not only accretion but also,
counter-intuitively,
the expulsion of matter in the form of highly supersonic outflows. Although
this phenomenon has been seen in young stars, a fundamental question is
whether
it also occurs amongst newborn brown dwarfs: these are the so-called 'failed
stars', with masses between stars and planets, that never manage to reach
temperatures high enough for normal hydrogen fusion to occur. Recently,
evidence for accretion in young brown dwarfs has mounted, and their spectra
show lines that are suggestive of outflows. Here we report
spectro-astrometric
data that spatially resolve an outflow from a brown dwarf. The outflow's
characteristics appear similar to, but on a smaller scale than, outflows
from
normal young stars. This result suggests that the outflow mechanism is
universal, and perhaps relevant even to the formation of planets.

\\ ( http://arXiv.org/abs/astro-ph/0506485 , 283kb)
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Paper: astro-ph/0506493
Date: Tue, 21 Jun 2005 13:34:10 GMT (293kb)

Title: Crossing into the substellar regime in Praesepe

Authors: R.J. Chappelle (1), D.J. Pinfield (1,2), I.A. Steele (1), P.D.
Dobbie
(3), A. Magazzu (4) ((1) Liverpool John Moores Uni (2) University of
Hertfordshire (3) University of Leicester (4) Fundacion Galileo
Galilei-INAF)
Comments: 17 pages, 13 figures, accepted for publication in MNRAS
\\
We present the results of a deep optical 2.6 square degree survey with near
infrared follow-up measurements of the intermediate-aged Praesepe open
cluster.
The survey is complete to I=21.3, Z=20.5, corresponding to ~0.06 Solar
Masses
assuming a cluster age of 0.5 Gyrs. Using 3-5 pass-bands to constrain
cluster
membership, we identify 32 new low mass cluster members, at least 4 of which
are likely to be substellar. We use the low mass census to trace the region
where the sequence moves away from the NEXTGEN towards the Dusty regime at
Teff
= 2200K. In doing so, we identify four unresolved binaries, yielding a
substellar binary fraction of ~30 percent. The binary fractions appear to
decrease below 0.1 Solar Masses, in contrast to the rising fractions found
in
the Pleiades. We also identify a paucity of late M dwarfs, thought to be due
to
a steepening in the mass-luminosity relation at these spectral types, and
compare the properties of this gap in the sequence to those observed in
younger
clusters. We note an overdensity of faint sources in the region of the
so-called subcluster (possibly an older smaller cluster within Praesepe),
and
subsequently derive the luminosity and mass functions for the main Praesepe
cluster, revealing a turn-over near the substellar boundary. We conclude by
presenting astrometric measurements for low mass Praesepe candidates from
the
literature, and rule out as a likely foreground dwarf RPr1, hitherto thought
to
be a substellar member.

\\ ( http://arXiv.org/abs/astro-ph/0506493 , 293kb)

• Previous message: LARRY KLAES: "SETI public: Papers on Circumstellar/Protoplanetary Disks"

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