Документ взят из кэша поисковой машины. Адрес оригинального документа : http://master.sai.msu.ru/media/presentations/2012/arXiv05oct12_1.doc Дата изменения: Sun Oct 7 19:56:13 2012 Дата индексирования: Sat Feb 2 22:16:34 2013 Кодировка: Поисковые слова: ngc 891

arXiv:1210.0305


CFBDSIR2149-0403: a 4-7 Jupiter-mass free-floating planet in the young
moving group AB Doradus ?
Using the CFBDSIR wide field survey for brown dwarfs, we identified
CFBDSIRJ214947.2-040308.9, a late T dwarf with atypically red J-Ks colour.
We obtained an X-Shooter spectra, with signal detectable from 0.8 to 2.3
micron, which confirmed a T7 spectral type with an enhanced Ks-band flux
indicative of a potentially low-gravity, young, object. The comparison of
our near infrared spectrum with atmosphere models, for solar metallicity,
shows that CFBDSIRJ214947.2-040308.9 is probably a 650-750 K, log g=3.75-
4.0 substellar object. Using evolution models, this translates into a
planetary mass object, with an age in the 20-200 Myr range. An independent
Bayesian analysis from proper motion measurements results in a 87%
probability that this free-floating planet is a member of the 50-120 Myr
old AB Doradus moving group, which strengthens the spectroscopic youth
diagnosis. By combining our atmospheric characterisation with the age and
metallicity constraints arising from the probable membership to the AB
Doradus moving group, we find that CFBDSIRJ214947.2-040308.9 is probably a
4-7 Jupiter masses free-floating planet with an effective temperature of
~700K and a log g of ~4.0, typical of the late T-type exoplanets that are
targeted by direct imaging. We stress that this object could be used as a
benchmark for understanding the physics of the similar T-type exoplanets
that will be discovered by the upcoming high contrast imagers.

SN 2009ip in NGC 7259




Electronic Telegram No.
1928
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://www.cfa.harvard.edu/iau/cbat.html


SUPERNOVA 2009ip IN NGC 7259
J. Maza, M. Hamuy, R. Antezana, L. Gonzalez, P. Gonzalez, P. Lopez, S.
Silva, G. Folatelli, D. Iturra, R. Cartier, F. Forster, S. Marchi, and A.
Rojas, Universidad de Chile; G. Pignata, Universidad Andres Bello; B.
Conuel,
Wesleyan University; and D. Reichart, K. Ivarsen, J. Haislip, A. Crain, D.
Foster, M. Nysewander, and A. LaCluyze, University of North Carolina at
Chapel Hill, on behalf of the CHASE project, report the discovery of an
apparent supernova (mag approximately 17.9 +/- 0.3) on an unfiltered image
taken on Aug. 26.11 UT with the 0.41-m 'PROMPT 3' telescope located at
Cerro
Tololo. The new object is located at R.A. = 22h23m08s.26 +/- 0".1, Decl. =
-28o56'52".4 +/- 0".1 (equinox 2000.0), which is about 36".2 east and 25".1
north of the center of the galaxy NGC 7259. Additional magnitudes for
2009ip: 2008 Oct. 7.09, [19.0; 2009 Aug. 21.14, [18.0; 24.08, 18.5 +/-
0.4;
28.00; 17.0 +/- 0.3.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.

(C) Copyright 2009 CBAT
2009 August 29 (CBET 1928) Daniel W. E.
Green

A New Luminous Outburst from SN 2009ip

ATel #4334; A. J. Drake (Caltech); S. Howerton (Arkansas City, KS); R.
McNaught (ANU); S. G. Djorgovski, A. A. Mahabal, M. J. Graham, R. Williams
(Caltech); J. Prieto (Princeton); M. Catelan (PUC Chile); E. Christensen,
S. Larson (UA/LPL)

on 24 Aug 2012; 21:35 UT

Credential Certification: Andrew J. Drake (ajd@cacr.caltech.edu)
Subjects: Optical, Supernovae, Transient, Variables
Referred to by ATel #: 4338, 4412, 4423, 4427, 4430, 4435, 4439
Further to Drake et al. (2010, Atel#2897), we report the discovery of a new
bright outburst from spectroscopically confirmed LBV (Supernova Impostor)
SN 2009ip (Maza et al. 2009; CBET#1928, Berger et al. 2009, ATEL#2184;
Smith et al. 2010; Foley et al. 2011) in images taken by the Siding Spring
Survey (SSS).
During the normal operation of the CRTS SN Hunt project, an outburst of SN
2009ip was discovered in subtracted images of NGC 7259 taken on 2012 July
24th UT. In further observations taken on August 14th the source was found
to have brightened to V=16.8(0.1). This is the highest state observed in
SSS data since it was first observed 2005. Additional SSS observations
taken on Aug 16th and Aug 19th show the source remaining at similar
brightness (V~16.8 +/- 0.1). Based on the distance to host galaxy NGC 7259
(m-M =31.55; NED), the SSS photometry suggests that absolute magnitude of
SN 2009ip is currently Mv < -14.5.
Given the current very high state of this LBV, we request spectroscopic
follow-up to determine the nature of this outburst.
[pic]
relativistic evolution does indeed produce a runaway instability.
[7] arXiv:1210.1215 [pdf, ps, other]
The faster the narrower: characteristic bulk velocities and jet
opening angles of Gamma Ray Bursts
G. Ghirlanda (1), G. Ghisellini (1), R. Salvaterra (2), L. Nava (3),
D. Burlon (4), G. Tagliaferri (1), S. Campana (1), P. D'Avanzo (1), A.
Melandri (1) ((1) INAF-Osservatorio Brera, (2) INAF-IASF Milano, (3)
APC - Paris, (4) Sydney Institute for Astronomy)
Comments: 15 pages, 8 figures, 1 table. Accepted for publication in
MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The jet opening angle theta_jet and the bulk Lorentz factor Gamma_0
are crucial parameters for the computation of the energetics of Gamma
Ray Bursts (GRBs). From the ~30 GRBs with measured theta_jet or
Gamma_0 it is known that: (i) the real energetic E_gamma, obtained by
correcting the isotropic equivalent energy E_iso for the collimation
factor ~theta_jet^2, is clustered around 10^50-10^51 erg and it is
correlated with the peak energy E_p of the prompt emission and (ii)
the comoving frame E'_p and E'_gamma are clustered around typical
values. Current estimates of Gamma_0 and theta_jet are based on
incomplete data samples and their observed distributions could be
subject to biases. Through a population synthesis code we investigate
whether different assumed intrinsic distributions of Gamma_0 and
theta_jet can reproduce a set of observational constraints. Assuming
that all bursts have the same E'_p and E'_gamma in the comoving frame,
we find that Gamma_0 and theta_jet cannot be distributed as single
power-laws. The best agreement between our simulation and the
available data is obtained assuming (a) log-normal distributions for
theta_jet and Gamma_0 and (b) an intrinsic relation between the peak
values of their distributions, i.e theta_jet^2.5*Gamma_0=const. On
average, larger values of Gamma_0 (i.e. the "faster" bursts)
correspond to smaller values of theta_jet (i.e. the "narrower"). We
predict that ~6% of the bursts that point to us should not show any
jet break in their afterglow light curve since they have
sin(theta_jet)<1/Gamma_0. Finally, we estimate that the local rate of
GRBs is ~0.3% of all local SNIb/c and ~4.3% of local hypernovae, i.e.
SNIb/c with broad-lines.
[21] arXiv:1210.1294 [pdf, other]
The Shortest Known Period Star Orbiting our Galaxy's Supermassive
Black Hole
L. Meyer, A. M. Ghez, R. Schoedel, S. Yelda, A. Boehle, J. R. Lu, T.
Do, M. R. Morris, E. E. Becklin, K. Matthews
Comments: Science, in press (published Oct 5, 2012). See Science
Online for the Supplementary Material, or here: this http URL
Subjects: Galaxy Astrophysics (astro-ph.GA)
Stars with short orbital periods at the center of our galaxy offer a
powerful and unique probe of a supermassive black hole. Over the past
17 years, the W. M. Keck Observatory has been used to image the
Galactic center at the highest angular resolution possible today. By
adding to this data set and advancing methodologies, we have detected
S0-102, a star orbiting our galaxy's supermassive black hole with a
period of just 11.5 years. S0-102 doubles the number of stars with
full phase coverage and periods less than 20 years. It thereby
provides the opportunity with future measurements to resolve
degeneracies in the parameters describing the central gravitational
potential and to test Einstein's theory of General Relativity in an
unexplored regime.
arXiv:1210.1183 (cross-list from gr-qc) [pdf, ps, other]
Do Intergalactic Magnetic Fields Imply An Open Universe?
J. D. Barrow, C. G. Tsagas, K. Yamamoto
Comments: 6 pages, no figures
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology
and Extragalactic Astrophysics (astro-ph.CO)
The detection of magnetic fields at high redshifts, and in empty
intergalactic space, support the idea that cosmic magnetism has a
primordial origin. Assuming that Maxwellian electromagnetism and
general relativity hold, and without introducing any `new' physics, we
show how the observed magnetic fields can easily survive cosmological
evolution from the inflationary era in a marginally open Friedmann
universe but fail to do so, by a very wide margin, in a flat or a
marginally closed universe. Magnetic fields evolve very differently in
open and closed Friedmann models. The existence of significant
magnetic fields in the universe today, that require primordial
seeding, may therefore provide strong evidence that the universe is
marginally open and not marginally closed.