J/A+A/389/439 Photometry in field of RX J004404.8+411820 (Nedialkov+, 2002)
First optical identification of a supersoft X-ray source in M31.
Nedialkov P., Orio M., Birkle K, Conselice C., Della Valle M., Greiner J.,
Magnier E., Tikhonov N.A.
<Astron. Astrophys. 389, 439 (2002)>
=2002A&A...389..439N 2002A&A...389..439N
ADC_Keywords: X-ray sources ; Cross identifications ; Photometry, UBVRI
Keywords: stars: novae, cataclysmic variables - X-rays: stars
Abstract:
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 1.644 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.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 93 86 Photometry obtained for all the stars in the
ROSAT-PSPC error circle of 15 arcsec
table3.tex 132 174 LaTeX version of table3
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See also:
II/208 : BVRI CCD photometry in the field of M 31 (Magnier+ 1992)
J/A+AS/92/625 : Ionized nebulae in M31 (Walterbos+ 1992)
J/A+A/317/328 : ROSAT PSPC survey of M 31 (Supper+ 1997)
J/A+A/373/63 : M31 second ROSAT PSPC survey (Supper+, 2001)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/86] Sequential number
4- 7 F4.1 arcsec Dist Angular distance from the position of the
supersoft X-ray source, RX J004404.8+411820
9- 10 I2 h RAh Right ascension (J2000)
12- 13 I2 min RAm Right ascension (J2000)
15- 18 F4.2 s RAs Right ascension (J2000)
20 A1 --- DE- Declination sign (J2000)
21- 22 I2 deg DEd Declination (J2000)
24- 25 I2 arcmin DEm Declination (J2000)
27- 30 F4.1 arcsec DEs Declination (J2000)
32- 36 F5.2 mag Vmag ? V magnitude
38- 41 F4.2 mag e_Vmag ? rms uncertainty on Vmag
43- 47 F5.2 mag B-V ? B-V colour index or Bmag if n_B-V=B
48 A1 --- n_B-V [B] If B, then B magnitude in B-V column
50- 53 F4.2 mag e_B-V ? rms uncertainty on B-V or Bmag
55- 59 F5.2 mag V-R ? V-R colour index or Rmag if n_V-R=R
60 A1 --- n_V-R [R] If R, then R magnitude in V-R column
62- 65 F4.2 mag e_V-R ? rms uncertainty on V-R or Rmag
67- 71 F5.2 mag R-I ? R-I colour index or Imag if n_R-I=I
72 A1 --- n_R-I [I] If I, then I magnitude on R-I column
74- 77 F4.2 mag e_R-I ? rms uncertainty on R-I or Imag
79- 93 A15 --- Id Identifications (1)
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Note (1): Identifications:
NNNNNN: [MLV92] NNNNNN, Magnier et al. (1992, Cat. II/208)
k282: [WB92a] 282, Walterbos & Braun, 1992, Cat. J/A+AS/92/625)
The nova candidate is star No.2
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Acknowledgements: Marina Orio
(End) Patricia Bauer [CDS] 19-Apr-2002