More than two hundred and fifty thousand spectroscopic binary or variable star candidates discovered by LAMOST

About 786.4 thousand stars were observed by LAMOST twice or more during the first stage of its spectroscopic survey. The radial velocity differences for about 256 thousand targets are larger than10 km s^-1 and they are possible spectroscopic binary or variable candidates(SBVCs). It is shown that most SBVCs are slightly metal poorer than the Sun. There are two peaks in the temperature distribution of SBVCs around 5760 K and 4870 K, while there are three peaks in the distribution of the gravitational acceleration at 2.461, 4.171 and 4.621 cm s^-2. The locations of SBVCs on the [Fe/H]-T, [Fe/H]-log g, log g-T and H-R diagrams are investigated. It is found that the detected SBVCs could be classified into four groups. The first group has higher log g～4.621 and lower T ～ 4870 K which are mainly cool red dwarf binaries. The second group of SBVCs has logg around 4.171 cm s^-2 that includes binaries and pulsating stars such as δSet and γ Dor variables. The gravitational accelerations of the third group of SBVCs are higher and some of them are below the zero-age main sequence. They may be contact binaries in which the primary components are losing energy to the secondaries in the common envelopes and are at a special stellar evolutionary stage.The last group is composed of giants or supergiants with log g around 2.461 cm s^-2 that may be evolved pulsating stars. One target(C134624.29+333921.2) is confirmed as an eclipsing binary with a period of 0.65 days. A preliminary analysis suggests that it is a detached binary with a mass ratio of 0.46. The primary fills its critical Roche lobe by about 89%, indicating that mass transfer will occur between the two components.     

Populations of Bright X-ray Sources in the Starburst Galaxies NGC 4038/4039

Assuming a naive star formation history, we construct synthetic X-ray source pop- ulations, using a population synthesis code, for comparison with the observed X-ray lumi- nosity function (XLF) of the interacting galaxies NGC 4038/4039. We have included high- and intermediate-mass X-ray binaries, young rotation-powered pulsars and fallback disk-fed black holes in modeling the bright X-ray sources detected. We find that the majority of the X-ray sources are likely to be intermediate-mass X-ray binaries, but for typical binary evolu- tion parameters, the predicted XLF seems to be steeper than observed. We note that the shape of the XLFs depends critically on the existence of XLF break for young populations, and suggest super-Eddington accretion luminosities or the existence of intermediate-mass black holes to account for the high luminosity end and the slope of the XLF in NGC 4038/4039.     

2MASS near-infrared photometry of symbiotic stars

We present Two Micron All Sky Survey photometry for 216 symbiotic and possible symbiotic stars. This represents the most comprehensive near-infrared photometry for these sources which has been published to date. The results are used to define the statistics of S- and D-type stars; to investigate the photometric properties of Magellanic S-type symbiotics; and to define the possible evolution of D-type symbiotics within the J − H / H − K _S colour plane. It appears that the colours of D-type symbiotics are consistent with differing mass-loss rates d M /d t , provided that the grains have a silicate-like composition, and maximum temperatures of the order of ∼800 K.     

New INTEGRAL sources and TeV emission

INTEGRAL is operational since more than three years and producing high quality data that allows to detect fainter new hard X-ray sources. The new sources, identified until now, are mostly active galactic nuclei and absorbed or transient high mass X-ray binaries. TeV emission could be expected from the new high mass X-ray binaries accreting dense clumps of stellar wind. INTEGRAL sources with TeV counterparts are discussed. Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), Czech Republic and Poland, and with the participation of Russia and the USA.