Field Stars (field + star)

Distribution by Scientific Domains


Selected Abstracts


Results from the Wide Angle Search for Planets Prototype (WASP0) , III.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005
Planet hunting in the Draco field
ABSTRACT The Wide Angle Search for Planets Prototype (WASP0) is a wide-field instrument used to search for extra-solar planets via the transit method. Here we present the results of a monitoring program which targeted a 9-degree field in Draco. WASP0 monitored 35 000 field stars for two consecutive months. Analysis of the light curves resulted in the detection of 11 multi-transit candidates and three single-transit candidates, two of which we recommend for further follow-up. Monte Carlo simulations matching the observing parameters estimate the expected number of transit candidates from this survey. A comparison of the expected number with the number of candidates detected is used to discuss limits on planetary companions to field stars. [source]


Gemini/GMOS imaging of globular clusters in the Virgo galaxy NGC 4649 (M60)

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2004
Duncan A. Forbes
ABSTRACT We present Sloan g and i imaging from the Gemini Multi-object Spectrograph (GMOS) instrument on the Gemini North telescope for the globular cluster (GC) system around the Virgo galaxy NGC 4649 (M60). Our three pointings, taken in good seeing conditions, cover an area of about 90 square arcmin. We detect 2151 unresolved sources. Applying colour and magnitude selection criteria to this source list gives 995 candidate GCs. Our source list is greater than 90 per cent complete to a magnitude of i= 23.6, and has little contamination from background galaxies. We find fewer than half a dozen potential ultracompact dwarf galaxies around NGC 4649. Foreground extinction from the nearby spiral NGC 4647 is limited to be AV < 0.1. We confirm the bimodality in the GC colour distribution found by earlier work using Hubble Space Telescope/WFPC2 imaging. As is commonly seen in other galaxies, the red GCs are concentrated towards the centre of the galaxy, having a steeper number density profile than the blue GC subpopulation. The varying ratio of red-to-blue GCs with radius can largely explain the overall GC system colour gradient. The underlying galaxy starlight has a similar density profile slope and colour to the red GCs. This suggests a direct connection between the galaxy field stars and the red GC subpopulation. We estimate a total GC population of 3700 ± 900, with the uncertainty dominated by the extrapolation to larger radii than observed. This total number corresponds to a specific frequency SN= 4.1 ± 1.0. Future work will present properties derived from GMOS spectra of the NGC 4649 GCs. [source]


A uvby, photometric analysis of the Monoceros star-forming field

ASTRONOMISCHE NACHRICHTEN, Issue 4 2010
N. Kaltcheva
Abstract This investigation presents a new analysis of the spatial distribution of the bright early-type stars in the field of Northern Monoceros. A database of all O,B9 stars with available uvby, photometry is collated and a homogeneous distance scale is established for the clusters and layers of field stars. We provide revised distances for NGC 2264 and NGC 2244 of 833±38 (s.e.) pc and 1585±60 (s.e.) pc, respectively. We present arguments that there might be substructures in the clusters projected along the line of sight. According to the present sample the classical Mon OB2 association at 1.6 kpc is represented by a relatively compact group at 1.26 kpc in the vicinity of NGC 2244 and a layer of massive stars located between 1.5 and 3 kpc (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


A catalogue of stars suspected of bright active regions

ASTRONOMISCHE NACHRICHTEN, Issue 1 2009
M. Zboril
Abstract We present a catalogue of field stars across the HR diagram suspected of bright active regions in their atmospheres. We aim at developing the first version of a database of active stars with bright regions (bright spots). Using a variety of databases and the internet we found and gathered all relevant archival data starting about 1973 and being important for developing such a catalogue. We found that the phenomenon starspot is now common to a variety of spectral type and luminosity classes. Our primary goal was to identify active solar and late type stars suspicious of bright active regions but the search offers expanded results including young T Tauri stars, eclipsing binaries with equal or mixed spectral types components (Algols,WUMa stars) and in some cases other types of objects. Moreover, the light curves analyses for eclipsing binaries offer reliable estimates for spot properties and it was found that 20% of binaries in the catalogue had a spot located near the L point (neck zone). At present, the catalogue consists of 134 stars and overall characteristics for them are organised in several files in ASCII format. The catalogue is electronically available (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]