This paper presents a new sample of BL Lac objects selected from a deep (30mJy) radio survey of flat spectrum radio sources (the CLASS blazar survey). The sample is one of the largest well-defined samples in the low-power regime with a total of 130 sources of which 55 satisfy the 'classical' optical BL Lac selection criteria, and the rest have indistinguishable radio properties. The primary goal of this study is to establish the radio luminosity function (RLF) on firm statistical ground at low radio luminosities where previous samples have not been able to investigate. The gain of taking a peek at lower powers is the possibility to search for the flattening of the luminosity function which is a feature predicted by the beaming model but which has remained elusive to observational confirmation. In this study, we extend for the first time the BL Lac RLF down to very low radio powers ~10^22^W/Hz, i.e. two orders of magnitude below the RLF currently available in the literature. In the process, we confirm the importance of adopting a broader, and more physically meaningful set of classification criteria to avoid the systematic missing of low-luminosity BL Lacs. Thanks to the good statistics we confirm the existence of weak but significant positive cosmological evolution for the BL Lac population, and we detect, for the first time the flattening of the RLF at L~10^25^W/Hz in agreement with the predictions of the beaming model.
The light curves of 252 B-star candidates in the Kepler database are analyzed in a similar fashion to that done by Balona et al. (2011MNRAS.413.2403B) to further characterize B-star variability, increase the sample of variable B stars for future study, and to identify stars whose power spectra include particularly interesting features such as frequency groupings. Stars are classified as either constant light emitters, {beta} Cep stars, slowly pulsating B stars (SPBs), hybrid pulsators, binaries or stars whose light curves are dominated by rotation (Bin/Rot), hot subdwarfs, or white dwarfs. One-hundred stars in our sample were found to be either light constants or to be variable at a level of less than 0.02mmag. We increase the number of candidate B-star variables found in the Kepler database by Balona et al. (2011MNRAS.413.2403B) in the following fashion: {beta} Cep stars from 0 to 10, SPBs from eight to 54, hybrid pulsators from seven to 21, and Bin/Rot stars from 23 to 82. For comparison purposes, approximately 51 SPBs and six hybrids had been known prior to 2007. The number of {beta} Cep stars known prior to 2004 was 93. A secondary result of this study is the identification of an additional 11 pulsating white dwarf candidates, four of which possess frequency groupings.
We subjected 106 new high-resolution spectra of the double-lined spectroscopic close binary epsilon Lupi, obtained in a time-span of 17 days from two different observatories, to a detailed study of orbital and intrinsic variations. We derived accurate values of the orbital parameters. We refined the sidereal orbital period to 4.55970 days and the eccentricity to e=0.277. By adding old radial velocities, we discovered the presence of apsidal motion, with a period of the rotation of apses of about 430 years. Such a value is in agreement with theoretical expectations. Additional data is needed to confirm and refine this value. Our dataset did not allow to derive the orbit of the third body, which is known to orbit the close system in approximately 64 years. We present the secondary of epsilon Lupi as a new beta Cephei variable, while the primary is a beta Cephei suspect. A first detailed analysis of line-profile variations of both primary and secondary led to the detection of one pulsation frequency near 10.36c/d in the variability of the secondary, while no clear periodicity was found in the primary, although low-amplitude periodicities are suspected. The limited accuracy and extent of our dataset did not allow any further analysis, such as mode-identification.
The nature of galaxy structures on large scales is a key observational prediction for current models of galaxy formation. The Sloan Digital Sky Survey (SDSS) and the 2dF galaxy survey have revealed a number of structures on 40-150h<SUP>–1</SUP>Mpc scales at low redshifts, and some even larger ones. To constrain galaxy number densities, luminosities, and stellar populations in large structures at higher redshift, we have investigated two sheet-like structures of galaxies at z=0.8 and 1.3 spanning 150h<SUP>–1</SUP> comoving Mpc embedded in large quasar groups (LQGs) extending over at least 200h<SUP>–1</SUP>Mpc. We present first results of an analysis of these sheet-like structures using two contiguous 1° Galaxy Evolution Explorer (GALEX) fields (FUV and NUV) cross-correlated with optical data from the SDSS. We derive a sample of 462 Lyman break galaxy (LBG) candidates coincident with the sheets. Using the GALEX and SDSS data, we show that the overall average spectral energy distribution of a LBG galaxy at z∼1 is flat (in f<SUB>λ</SUB>) in the rest-frame wavelength range from 1500Å to 4000Å, implying evolved populations of stars in the LBGs. From the luminosity functions we get indications for overdensities in the two LQGs compared to their foreground regions.
A new catalogue of clusters in the Large Magellanic Cloud has been constructed from searches of the IIIa-J component of the ESO/SERC Southern Sky Atlas. The catalogue contains coordinate and diameter measurements of 1762 clusters in a 25x25{deg} area of sky centred on the LMC, but excluding the very crowded 3.5 square deg. region around the Bar. The distribution of these clusters appears as two superimposed elliptical systems. The higher density inner system extends over about 8d; the lower density outer system can be represented by 13d X 10d disc inclined at 42d to the line of sight. There are suggestions of two weak "arms" in the latter.
This is CMC12 (Version 1.0), an astrometric and photometric catalogue of 6.3 million stars in the red magnitude range 9 to 17. The Carlsberg Meridian Telescope (CMT) underwent a major upgrade in March 1999. A 2k by 2k CCD camera was installed with a Sloan r' filter operating in a drift scan mode. With the new system, the magnitude limit is r'_CMT_=17 and the positional accuracy is about 0.035". The main task of the CMT is to map the sky in the declination range -3{deg} to +30{deg} with the aim of providing an astrometric, and photometric, catalogue that can accurately transfer the Hipparcos/Tycho reference frame to Schmidt plates. The current release (Version 1.0) comprises all the observations made between March 1999 and March 2002 with the new CCD in the declination band -3{deg} to +3{deg}. It is intended to release the rest of the catalogue later. A more complete description is available in the documentation at http://www.ast.cam.ac.uk/~dwe/SRF/cmc12/cmc12_documentation.ps or http://www.ast.cam.ac.uk/~dwe/SRF/cmc12/cmc12_documentation.pdf
The Canadian Network for Observational Cosmology Field Galaxy Redshift Survey (CNOC2) obtained spectroscopic redshifts for about 6200 galaxies to a nominal limit of R=21.5. The survey area of about 1.5 square degrees was spread over four patches on the sky. This catalog presents photometry and redshifts for all galaxies in the CNOC2 0223+00 Patch (area of 1409 square arcminutes). A future paper will provide catalogs for the other three patches.
Multiple star systems are commonly assumed to form coevally; they thus provide the anchor for most calibrations of stellar evolutionary models. In this paper, we study the binary population of the Taurus-Auriga association, using the component positions in an HR diagram in order to quantify the frequency and degree of coevality in young binary systems. After identifying and rejecting the systems that are known to be affected by systematic errors (due to further multiplicity or obscuration by circumstellar material), we find that the relative binary ages, |{Delta}log{tau}|, have an overall dispersion {sigma}_|{Delta}log{tau}|_~0.40dex.
The tutorial uses VOSA to analyse members of the Collinder 69 open
cluster by crossmatching a given local set of objects and accesses VO
services to crossmatch the objects with 2MASS to receive colors. The
resulting SEDs are analysed using different fit functions.
The Arecibo Ultra-Deep Survey (AUDS) is a blind HI survey aimed at detecting galaxies beyond the local Universe in the 21-cm emission line of neutral hydrogen (HI). The Arecibo L-band Feed Array (ALFA) was used to image an area of 1.35deg^2^ to a redshift depth of 0.16, using a total on-source integration time of over 700h. The long integration time and small observation area makes it one of the most sensitive HI surveys, with a noise level of ~75{mu}Jy per 21.4kHz (equivalent to 4.5km/s at redshift z=0). We detect 247 galaxies in the survey, more than doubling the number already detected in AUDS60. The mass range of detected galaxies is log(M_HI_[h_70_^-2^M_{sun}_])=6.32-10.76. A modified maximum likelihood method is employed to construct an H I mass function (HIMF). The best fitting Schechter parameters are low-mass slope {alpha}=-1.37+/-0.05, characteristic mass log(M^*^[h_70_^-2^M_{sun}_])=10.15+/-0.09, and density {Phi}_*_=(2.41+/-0.57)x10^-3^h_70_^3^Mpc^-3^/dex. The sample was divided into low- and high-redshift bins to investigate the evolution of the HIMF. No change in low-mass slope {alpha} was measured, but an increased characteristic mass M*, was noted in the higher redshift sample. Using Sloan Digital Sky Survey data to define relative galaxy number density, the dependence of the HIMF with environment was also investigated in the two AUDS regions. We find no significant variation in {alpha} or M*. In the surveyed region, we measured a cosmic HI density {Omega}_HI_=(3.55+/-0.30)x10^-4^h_70_^-1^. There appears to be no evolutionary trend in {Omega}_HI_ above 2{sigma} significance between redshifts of 0 and 0.16.
