The stellar content of the XMM-Newton bright serendipitous survey

Context. The comparison of observed counts in a given sky direction with predictions by Galactic models yields constraints on the spatial distribution and the stellar birthrate of young stellar populations. The XMM-Newton Bright Serendipitous Survey (XBSS) is an unbiased survey that includes a total of 58 stellar sources selected in the 0.5–4.5 keV energy band, having a limiting sensitivity of 10 −2 cnt s −1 and covering an area of 28.10 sq deg. Aims. We present the results of analysing the stellar content of the XBSS so as to understand the recent star formation history of the Galaxy in the vicinity of the Sun. Methods. We compared the observations with the predictions obtained with XCOUNT, a model of the stellar X-ray content of the Galaxy. The model predicts the number and properties of the stars to be observed in terms of magnitude, colour, population and fx/fv ratio distributions of the coronal sources detected with a given instrument and sensitivity in a specific sky direction. Results. As in other shallow surveys, we observe an excess of stars not predicted by our Galaxy model. Comparing the colours of the identified infrared counterparts with the model predictions, we observe that this excess is produced by yellow (G+K) stars. The study of the X-ray spectrum of each source reveals a main population of stars with the coronal temperature stratification typical of intermediate-age stars. As no assumptions have been made for the selection of the sample, our results must be representative of the entire solar neighbourhood. Some stars show infrared excess due to circumstellar absorption, which is indicative of youth.

[1]  E. Feigelson,et al.  Determination of the gas-to-dust ratio in nearby dense clouds using X-ray absorption measurements , 2003, astro-ph/0306447.

[2]  F. R. Harnden,et al.  X-ray spectra and the rotation-activity connection of RS Canum Venaticorum binaries , 1986 .

[3]  M. J. Page,et al.  Exploring the X-ray sky with the XMM-Newton bright serendipitous survey , 2004, astro-ph/0407481.

[4]  D. M. Alexander,et al.  The Chandra Deep Field North Survey. V. 1 Ms Source Catalogs , 2001, astro-ph/0108404.

[5]  M. J. Page,et al.  The XMM-Newton HBS28 sample: Studying the obscuration in hard X-ray selected AGNs , , 2004 .

[6]  F. Favata,et al.  Stellar Birthrate in the Galaxy: Constraints from X-Ray Flux-limited Surveys , 1993 .

[7]  Jay A. Bookbinder,et al.  Einstein Observatory survey of X-ray emission from solar-type stars - The late F and G dwarf stars , 1987 .

[8]  Ulrich G. Briel,et al.  Overview of the ROSAT North Ecliptic Pole Survey , 2001 .

[9]  J. Schmitt,et al.  ROSAT All-Sky Survey Observations of the Hyades , 1995 .

[10]  Astrophysics,et al.  The HELLAS2XMM Survey. I. The X-Ray Data and the log N-log S Relation , 2001, astro-ph/0108514.

[11]  F. R. Harnden,et al.  Einstein Observatory coronal temperatures of late-type stars , 1990 .

[12]  R. Rosenfeld.  Nature , 2009, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[13]  Manuel Güdel,et al.  The X-Ray Sun in Time: A Study of the Long-Term Evolution of Coronae of Solar-Type Stars , 1997 .

[14]  P. Szkody,et al.  The new AM Her system RX J0704.2+6203 Northern twin of BL Hydri , 2001, astro-ph/0110050.

[15]  J. Stenflo,et al.  Solar and stellar magnetic fields: Origins and coronal effects , 1983 .

[16]  S. Sciortino,et al.  X-ray variability of Pleiades late-type stars as observed with the ROSAT-PSPC , 2003 .

[17]  N. Grevesse,et al.  Abundances of the elements: Meteoritic and solar , 1989 .

[18]  University of Leicester,et al.  XMM-Newton and the Pleiades – I. Bright coronal sources and the X-ray emission from intermediate-type stars , 2003, astro-ph/0307095.

[19]  D. C. Barry.  The Chromospheric Age Dependence of the Birthrate, Composition, Motions, and Rotation of Late F and G Dwarfs within 25 Parsecs of the Sun , 1988 .

[20]  Glenn E. Miller,et al.  The Initial mass function and stellar birthrate in the solar neighborhood , 1979 .

[21]  F. R. Harnden,et al.  Einstein X-ray survey of the Pleiades - the dependence of X-ray emission on stellar age , 1985 .

[22]  B. Twarog.  The chemical evolution of the solar neighborhood. II - The age-metallicity relation and the history of star formation in the galactic disk , 1980 .

[23]  R. Wielen,et al.  Velocity Distribution of Stars and Relaxation in the Galactic Disk , 1983 .

[24]  E. Sion,et al.  FAR-ULTRAVIOLET AND OPTICAL SPECTROSCOPY OF THE DETACHED WHITE DWARF-M DWARF BINARY RE J1629+780 , 1995 .

[25]  S. Sciortino,et al.  The Einstein Observatory survey of stars in the Hyades cluster region , 1988 .

[26]  J. Healey.  The Preparation: , 2019, Walter Baade.

[27]  J. Kastner,et al.  ROSAT X-Ray Spectral Properties of Nearby Young Associations: TW Hydrae, Tucana-Horologium, and the β Pictoris Moving Group , 2002, astro-ph/0208589.

[28]  D. Liedahl,et al.  Collisional Plasma Models with APEC/APED: Emission-Line Diagnostics of Hydrogen-like and Helium-like Ions , 2001, astro-ph/0106478.

[29]  S. Basu,et al.  Multiplicity-corrected mass function of main-sequence stars in the solar neighborhood , 1992 .

[30]  D. M. Alexander,et al.  The Chandra Deep Field-North Survey. XVII. Evolution of Magnetic Activity in Old Late-Type Stars* , 2004 .

[31]  J. Villumsen.  Evolution of the velocity distribution in galactic disks , 1984 .

[32]  R. Schild,et al.  The Einstein Observatory Extended Medium-Sensitivity Survey. I - X-ray data and analysis , 1990 .

[33]  R. Rosner,et al.  The stellar composition of X-ray surveys from the Einstein Observatory , 1988 .

[34]  F. R. Harnden,et al.  In Orbit Performance of the Einstein Observatory/HEAO-2 Imaging Proportional Counter , 1981, IEEE Transactions on Nuclear Science.

[35]  F. R. Harnden,et al.  X-ray emission at the low-mass end - Results from an extensive Einstein Observatory survey , 1993 .

[36]  Ben Zuckerman,et al.  Young Stars Near the Sun , 2004 .

[37]  E. R. Breeveld,et al.  Detection of a new white-dwarf binary system in the extreme ultraviolet using the Rosat Wide Field Camera , 1992, Nature.

[38]  K. Arnaud.  XSPEC: The First Ten Years , 1996 .

[39]  Dan McCammon,et al.  Interstellar photoelectric absorption cross-sections, 0.03-10 keV , 1983 .

[40]  J. Bahcall,et al.  Models for the Galaxy and the Predicted Star Counts , 1979 .

[41]  Ucla,et al.  Exploring Terrestrial Planet Formation in the TW Hydrae Association , 2005, astro-ph/0506291.

[42]  M. Bessell,et al.  JHKLM PHOTOMETRY: STANDARD SYSTEMS, PASSBANDS, AND INTRINSIC COLORS , 1988 .

[43]  Stefanie Wachter,et al.  Cool Companions to White Dwarfs from the Two Micron All-Sky Survey Second Incremental Data Release , 2002, astro-ph/0212174.

[44]  John N. Bahcall,et al.  Star counts and galactic structure , 1986 .

[45]  C. Ryter.  Interstellar extinction from infrared to X-rays: An overview , 1996 .

[46]  F. R. Harnden,et al.  An Einstein Observatory X-ray survey of main-sequence stars with shallow convection zones , 1985 .

[47]  E. Feigelson,et al.  High-Energy Processes in Young Stellar Objects , 1999 .

[48]  R. Carlberg,et al.  The age-velocity-dispersion relation in the solar neighborhood , 1984 .

[49]  F. R. Harnden,et al.  ROSAT Observations of the Pleiades. I. X-Ray Characteristics of a Coeval Stellar Population , 1996 .