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J/A+A/318/111       ROSAT Galactic Plane Survey (Motch+ 1997)

The ROSAT Galactic Plane Survey: analysis of a low latitude sample area in Cygnus. Motch C., Guillout P., Haberl F., Pakull M.W., Pietsch W., Reinsch K. <Astron. Astrophys. 318, 111 (1997)> =1997A&A...318..111M (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources Mission_Name: ROSAT Keywords: X-ray: general - X-ray: stars - stars: activity - stars: neutron - stars: statistics Abstract: We present the analysis of the point source content of a low galactic latitude region selected from the ROSAT all-sky survey. The test field is centered at l=90, b=0 and has an area of 64.5deg2. A total of 128 soft X-ray sources are detected above a maximum likelihood of 8. Catalogue searches and optical follow-up observations show that in this direction of the galactic plane, 85% of the sources brighter than 0.03PSPC are identified with active coronae. F-K type stars represent 67% (±13%) of the stellar identifications and M type stars account for 19% (±6%). A small but significant number of X-ray sources are associated with A type stars on the basis of positional coincidence. These results together with those of similar optical campaigns demonstrate that the soft X-ray population of the Milky Way is largely dominated by active stars. We show that the density and distribution in flux and spectral type of the active coronae detected in X-rays are consistent with the picture drawn from current stellar population models and age dependent X-ray luminosity functions. The modelling of this population suggests that most of the stars detected by ROSAT in this direction are younger than 1Gyr. This opens the possibility to extract in a novel way large samples of young stars from the ROSAT all-sky survey. The small number of unidentified sources at low X-ray flux put rather strong constraints on the hypothetical X-ray emission from old neutron stars accreting from the interstellar medium. Our observations clearly rule out models which assume no dynamical heating for this population and a total number of Nns=109 neutron stars in the Galaxy. If accretion on polar caps is the dominant mode then our upper limit may imply Nns≃108. Among the non coronal identifications are three white dwarfs, a Seyfert 1 active nucleus, two early type stars and one cataclysmic variable. We also report the discovery of a Me+WD close binary system with Porb≃12 . File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table11 82 128 Optical identifications for sources with ML≥8 table12 82 30 Optical identifications for sources with 7≥ML≥8 tables.tex 96 217 LaTeX version of the tables supertab.sty 76 285 LaTeX utility
See also: IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1996) J/A+AS/122/201 : ROSAT Galactic Plane Survey observations (Motch+ 1997) Byte-by-byte Description of file: table11 table12
Bytes Format Units Label Explanations
1- 3 I3 --- Source Source index 5- 19 A15 --- ROSAT ROSAT name 21- 23 A3 --- Class Class of the proposed optical counterpart (1) 24 A1 --- u_Class [?] ? for the more uncertain cases (2) 26- 31 A6 --- SpType Spectral type 33- 51 A19 --- IdOpt Optical identification (2) 52 A1 --- u_IdOpt [?] ? for the more uncertain cases (2) 54- 58 F5.3 ct/s Count Count rate 60- 64 F5.3 ct/s e_Count rms uncertainty on Count 66- 71 F6.1 --- MaxLik Maximun likehood 73- 76 F4.2 % PPos Position probability 78 A1 --- l_PCaII Limit flag on CaII 79- 82 F4.2 % PCaII ? CaII H&K probability (3)
Note (1): AC: active corona AGN: active galactic nucleus CV: cataclysmic variable OB: OB star WD: White dwarf ??: Unknown Note (2): Proposed counterparts having a probability of identification in the range 95% - 98%, These more uncertain cases are marked by a '?' in the u_IdOpt column and in the u_Class column Note (3): Formal probability that if the star is responsible for the X-ray emission its chromospheric emission appears fainter or equal to the observed value.
Acknowledgements: Christian Motch
(End) Patricia Bauer [CDS] 18-Nov-1996
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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