[vsnet-alert 9884] SMC3 in eclipse?

Taichi Kato tkato at kusastro.kyoto-u.ac.jp
Wed Feb 6 11:03:11 JST 2008

  SMC3 in eclipse?

  The object is located in the region of ESO29-SC16
004819.8 -733154 (2000.0) SMC3 15.5: - ZAND 
004819.9 -733150 (2000.0) [MA93]218 em 

Finding chart:

The Astronomer's Telegram                   http://www.astronomerstelegram.org 
Posted: Mon Feb  4 01:30:01 EST 2008 -- Tue Feb  5 01:30:01 EST 2008
ATEL #1379							     ATEL #1379

Title:		The symbiotic star SMC 3
Author:	Andreas Zezas and Marina Orio
Queries:	orio at astro.wisc.edu
Posted:	4 Feb 2008;  9:29  UT
Subjects:	X-ray, Binaries, Variables, Stars

Andreas Zezas and Marina Orio report the XMM-Newton detection    of
the supersoft X-ray source (SSS) and symbiotic binary SMC 3,    17 years
after the first ROSAT detection, in a 20 ks exposure done    on 2007 October
28. The EPIC pn count rate with the medium filter    was  0.0315+-0.0019
counts/s.     SMC 3 was still a luminous SSS without a significant change
in the    effective temperature of about 500,000 K, but the luminosity
in the    0.15-1 keV range decreased by more than a factor of 4  since
the previous    XMM-Newton observation of 2006 (Orio et al., ApJ 2007,
661, 1105).    The X-ray flux was 3.1 10^{-13} erg/cm^2/s, still about
a factor of 10 higher    than  the flux measured a previous Chandra ACIS-S
observation done    in 2004, exactly 4 years and 8 months earlier. There
are no significant    spectral changes since the previous X-ray observations
and  the new    measurement seems  to confirm that SMC 3 undergoes an eclipse
in X rays,    lasting a few months and repeating itself with a period of
about    4.5 years, as suggested by Kahabka (2004, A&A, 416, 57). In this
last    X-ray observation the source was probably just coming out of the

Password Certification:  Marina Orio (orio at astro.wisc.edu)

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