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First optical identification of a supersoft X-ray source in M31

Nedialkov, P. and Orio, M. and Birkle, K. and Conselice, C. and Della Valle, M. and Greiner, J. and Magnier, E. A. and Tikhonov, N. A. (2002) First optical identification of a supersoft X-ray source in M31. Astronomy & Astrophysics, 389 (2). pp. 439-445. ISSN 0004-6361. doi:10.1051/0004-6361:20020575.

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We propose the first association of an optical counterpart with a luminous supersoft X-ray source in M31, RX J0044.0+4118, observed with ROSAT in July 1991. The PSPC position is at 1.6" angular distance from a candidate nova in outburst in September of 1990. This is interesting because the incidence of classical novae among supersoft X-ray sources is an open question. The proposed optical counterpart was measured at R ≃ 17.7 in September of 1990, and it had faded to R 〉 19.2 when it was observed again after 70 days. The light curve was too sparsely monitored for definite conclusions on the speed class of the nova. No other variable objects with V 〈23.5 were found in the ROSAT spatial error box. We evaluate that the probability that a classical or recurrent nova was in outburst in the ROSAT error box in the few years preceding the observation is very small, so the proposed identification is meaningful. We also show evidence that the associated supersoft X-ray source turned off in the third year after the outburst.

Item Type:Article
Related URLs:
URLURL TypeDescription
Conselice, C.0000-0003-1949-7638
Della Valle, M.0000-0003-3142-5020
Magnier, E. A.0000-0002-7965-2815
Additional Information:© 2002 ESO. Received: 19 December 2001. Accepted: 11 April 2002. We thank the following colleagues: R. Casalegno of INAF-Turin Observatory for his help with the mosaic photometric software in the early stage of this project, G. Ivanov and P. Kunchev for providing us with the M31 plates, obtained with the 2 m telescope of the BAS, R. Supper for the information on the second ROSAT survey of M31, C. Markwardt for computer support. This research has made use of the Simbad database, operated at CDS, Strasbourg, France. M. Orio acknowledges funding of the University of Wisconsin College of Letters and Sciences, of the Italian Space Agency (ASI) and a grant of the Italian Ministry of Instruction, University and Research for astrophysical research on compact objects.
Funding AgencyGrant Number
University of WisconsinUNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR)UNSPECIFIED
Subject Keywords:stars: novae, cataclysmic variables - X-rays: stars
Issue or Number:2
Record Number:CaltechAUTHORS:20180228-080326968
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Official Citation:First optical identification of a supersoft X-ray source in M31 P. Nedialkov, M. Orio, K. Birkle, C. Conselice, M. Della Valle, J. Greiner, E. Magnier and N. A. Tikhonov A&A, 389 2 (2002) 439-445 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84985
Deposited By: Ruth Sustaita
Deposited On:28 Feb 2018 21:17
Last Modified:15 Nov 2021 20:24

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