astro-ph coffee suggested papers for Thu, Dec 16, 2010 at 03:00:00 PM

astro-ph coffee will be held at the date and time above in the PAB 3rd-floor reading room. Some suggested papers of interest are listed below.

14 Dec 2010

We investigate the dynamical status of the low-mass globular cluster Palomar 13 by means of N-body computations to test whether its unusually high mass-to-light ratio of about 40 and its peculiarly shallow surface density profile can be caused by tidal shocking. Alternatively, we test - by varying the assumed proper motion - if the orbital phase of Palomar 13 within its orbit about the Milky Way can influence its appearance and thus may be the origin of these peculiarities, as has been suggeste...

15 Dec 2010

We report on the discovery of ETHOS 1 (PN G068.1+11.0), the first spectroscopically confirmed planetary nebula (PN) from a survey of the SuperCOSMOS Science Archive for high-latitude PNe. ETHOS 1 stands out as one of the few PNe to have both polar outflows (jets) travelling at $120\pm10$ km/s and a close binary central star. The lightcurve observed with the Mercator telescope reveals an orbital period of 0.535 days and an extremely large amplitude (0.816 mag) due to irradiation of the companion...

12 Dec 2010
[HTML None]

Robin M. Canup
Saturn's rings are more than 90-95% water ice, which implies that initially they were almost pure ice because they are continually polluted by rocky meteoroids. Saturn has only one large satellite, Titan, whereas Jupiter has four large satellites; additional large satellites probably existed originally but were lost as they spiralled into Saturn. Now, numerical simulations of the tidal removal of mass from a differentiated, Titan sized satellite as it migrates inward towards Saturn are reported....

13 Dec 2010

We searched for radio pulsars in 25 of the non-variable, unassociated sources in the Fermi LAT Bright Source List with the Green Bank Telescope at 820 MHz. We report the discovery of three radio and gamma-ray millisecond pulsars (MSPs) from a high Galactic latitude subset of these sources. All of the pulsars are in binary systems, which would have made them virtually impossible to detect in blind gamma-ray pulsation searches. They seem to be relatively normal, nearby (<=2 kpc) millisecond pu...

14 Dec 2010

A milestone of modern cosmology was the prediction and serendipitous discovery of the Cosmic Microwave Background (CMB), the radiation left over after decoupling from matter in the early evolutionary stages of the Universe. A prediction of the standard hot Big-Bang model is the linear increase with redshift of the black-body temperature of the CMB (TCMB). This radiation excites the rotational levels of some interstellar molecules, including carbon monoxide (CO), which can serve as cosmic thermo...

14 Dec 2010

Astronomy has played a major part in the development of civilisations, not only through conceptual developments, but most importantly through the very practical gains obtained through the observation of Sun, Moon planets and stars. Space sciences, including astronomy, have also played a major role in the development of modern societies, as engine for most subsequent space technology developments. Present trends tend to decrease the role of science in space development. This trend should be reve...

14 Dec 2010

We report the discovery and initial characterisation of Qatar-1b, a hot Jupiter orbiting a metal-rich K dwarf star, the first planet discovered by the Alsubai Project exoplanet transit survey. We describe the strategy used to select candidate transiting planets from photometry generated by the Alsubai Project instrument. We examine the rate of astrophysical and other false positives found during the spectroscopic reconnaissance of the initial batch of candidates. A simultaneous fit to the follo...

8 Dec 2010

NGC 3147, NGC 4698 and 1ES 1927+654 are active galaxies that are classified as Seyfert 2s, based on the line ratios of strong narrow emission lines in their optical spectra. However, they exhibit rapid X-ray spectral variability and/or little indication of obscuration in X-ray spectral fitting, contrary to expectation from the AGN unification model. Using optical spectropolarimetry with LRIS and near-infrared spectroscopy with NIRSPEC at the W. M. Keck Observatory, we conducted a deep search fo...

10 Dec 2010

Flux dependent non-linearity (reciprocity failure) in HgCdTe near infrared detectors can severely impact an instrument's performance, in particular with respect to precision photometric measurements. The cause of this effect is presently not understood. To investigate reciprocity failure, a dedicated test system was built. For flux levels between 1 and 50,000 photons/s, a sensitivity to reciprocity failure of approximately 0.1%/decade was achieved. A wavelength independent non-linearity due to ...

9 Dec 2010

We present methods and preliminary results of a relatively novel search for nearby stars. The method relies on photometric distance estimates as its primary search criterion, thus distinguishing itself from proper motion-based searches that have produced the bulk of nearby star discoveries.

10 Dec 2010

We present observations at 1.3 millimeters wavelength of the beta Pictoris debris disk with beam size 4.3 x 2.6 arcsec (83 x 50 AU) from the Submillimeter Array. The emission shows two peaks separated by ~7 arsec along the disk plane, which we interpret as a highly inclined dust ring or belt. A simple model constrains the belt center to 94+/-8 AU, close to the prominent break in slope of the optical scattered light. We identify this region as the location as the main reservoir of dust producing...

10 Dec 2010

We report the discovery of WASP-34b, a sub-Jupiter-mass exoplanet transiting its 10.4-magnitude solar-type host star (1SWASP J110135.89-235138.4; TYC 6636-540-1) every 4.3177 days in a slightly eccentric orbit (e = 0.038 +/- 0.012). We find a planetary mass of 0.59 +/- 0.01 M_Jup and radius of 1.22 ^{+0.11}_{-0.08} R_Jup. There is a linear trend in the radial velocities of 55+/-4 m/s/y indicating the presence of a long-period third body in the system with a mass > 0.45 M_Jup at a distance of...

13 Dec 2010

We present deep J-, H-, and Ks-band imaging data of the MOIRCS Deep Survey (MODS), which was carried out with Multi-Object Infrared Camera and Spectrograph (MOIRCS) mounted on the Subaru telescope in the GOODS-North region. The data reach 5sigma total limiting magnitudes for point sources of J=23.9, H=22.8, and Ks=22.8 (Vega magnitude) over 103 arcmin^2 (wide field). In 28 arcmin^2 of the survey area, which is ultra deep field of the MODS (deep field), the data reach the 5sigma depths of J=24.8...

10 Dec 2010

Three-body model fits to Arecibo and Goldstone radar data reveal the nature of two near-Earth asteroid triples. Triple asteroidal system 2001 SN263 is characterized by a primary of ~10^13 kg, an inner satellite ~1% as massive orbiting at ~3 primary radii in ~0.7 days, and an outer satellite ~2.5% as massive orbiting at ~13 primary radii in ~6.2 days. 1994 CC is a smaller system with a primary of mass ~2.6 \times 10^11 kg and two satellites ~2% and ~1% as massive orbiting at distances of ~5.5 an...

9 Dec 2010

We present the chemical abundance analysis of 33 red giant stars belonging to the complex stellar system Terzan 5. We confirm the discovery of two stellar populations (Ferraro et al. 2009, Nature, 462,483) with distinct iron abundances: a relatively metal-poor component with [Fe/H]=-0.25 +/- 0.07 r.m.s., and another component with [Fe/H]=+0.27 +/- 0.04 r.m.s., exceeding in metallicity any known Galactic globular cluster. The two populations also show different [alpha/Fe] abundance ratios. The m...

8 Dec 2010

Terrestrial planets are more likely to be detected if they orbit M dwarfs due to the favorable planet/star size and mass ratios. However, M dwarf habitable zones are significantly closer to the star than the one around our Sun, which leads to different requirements for planetary habitability and its detection. We review 1) the current limits to detection, 2) the role of M dwarf spectral energy distributions on atmospheric chemistry, 3) tidal effects, stressing that tidal locking is not synonymo...

8 Dec 2010

We have computed the fate of exoplanet companions around main sequence stars to explore the frequency of planet ingestion by their host stars during the red giant branch evolution. Using published properties of exoplanetary systems combined with stellar evolution models and Zahn's theory of tidal friction, we modeled the tidal decay of the planets' orbits as their host stars evolve. Most planets currently orbiting within 2 AU of their star are expected to be ingested by the end of their stars' ...

astroph.py v0.91ijc based on the original astroph.py. Updated 2010/12/16 14:57:12

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