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Searching for old neutron stars with ROSAT. I. Soft X-ray sources in molecular clouds at high galactic latitude

Danner, R. (1998) Searching for old neutron stars with ROSAT. I. Soft X-ray sources in molecular clouds at high galactic latitude. Astronomy and Astrophysics Supplement Series, 128 (2). pp. 331-348. ISSN 0365-0138. doi:10.1051/aas:1998383.

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This is the first in a series of three papers aiming to put strong observational constraints on the number of old accreting neutron stars in the Galaxy. Old neutron stars have been predicted to be visible as soft X-ray sources. The brightest sources are expected where the density of the interstellar medium is high. I present an X-ray survey of a complete sample of molecular clouds at high galactic latitudes based on the ROSAT All-Sky Survey. I detect 89 sources inside the projected contours of the molecular clouds and report on a comprehensive identification program. For all sources I searched astronomical catalogs and created finding charts. I also observed all sources at radio frequencies, most of them at 1.4 GHz and at 8 GHz. For sources with bright counterparts, optical spectra are presented. For fainter sources, optical CCD images are shown. Of all sources, 54 are securely identified and for the majority of the remaining sources likely identifications are given. I find no candidate for an old accreting neutron star in this sample. From this survey I derive an upper limit to the neutron star density of 50 sr^(-1) at a ROSAT count rate of 0.012 s^(-1).

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Additional Information:© European Southern Observatory (ESO), 1998. Received December 16, 1996; accepted August 1, 1997. This article is based on research conducted during my three year visit to the California Institute of Technology. I want to thank Prof. S.R. Kulkarni for his hospitality, support and countless discussions during this time. I am indebted to J. Trümper for his support of this project and many fruitful suggestions. The ROSAT project is supported by the German Bundesministerium für Bildung und Wissenschaft (BMBW/DARA) and the Max-Planck-Society. This research has made use of the NASA/IPAC extragalactic database NED) which is operated by the Jet Propulsion Laboratory, Caltech, under contract with the National Aeronautics and Space Administration, and of the SIMBAD database, operated at CDS, Strasbourg, France. The Digitized Sky Survey (DSS) was produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The National Radio Astronomy Observatory (NRAO) is operated by Associated Universities, Incorporated, under cooperative agreement with the National Science Foundation.
Group:Infrared Processing and Analysis Center (IPAC)
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Bundesministerium für Bildung und Wissenschaft (BMBW)UNSPECIFIED
Max Planck SocietyUNSPECIFIED
Subject Keywords:surveys / stars: neutron; white dwarfs / X-rays: stars / radio continuum: stars
Issue or Number:2
Record Number:CaltechAUTHORS:20180507-141344761
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Official Citation:Searching for old neutron stars with ROSAT - I. Soft X-ray sources in molecular clouds at high galactic latitude R. Danner Astron. Astrophys. Suppl. Ser., 128 2 (1998) 331-348 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86253
Deposited By: George Porter
Deposited On:08 May 2018 15:05
Last Modified:15 Nov 2021 20:36

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