The X-ray MEGA Campaign on Hot Stars: Previous Studies

• Gamma2 Velorum. We were granted an ASCA observation of this WC8+O7.5III colliding wind binary during apastron, at which time the WC star is in front of the O star.

  STATUS:The results of this observation (and comparison with earlier observations) are presented in Rauw et al. (2000, Monthly Notices, in press); a preprint is available in postscript and PDF formats.

• Iota Ori. We have been granted 2 ASCA observations of the colliding wind system Iota Ori to measure the effects of radiative braking.

  STATUS: The observations are completed and data has been analyzed. A paper by Pittard et al. describing the analysis of the ASCA and ROSAT spectra has been accepted by the MNRAS. A reprint is available in PDF format.

  Coordinated Observations. A paper by Marchenko et al. describing coordinated ground-based observations has been accepted for publication in the MNRAS. A reprint is available in PDF and Postscript format.

  • 6 spectra (including 2 simultaneous with the ASCA observation obtained at Ritter observatory by N. Morrison and C. Mulliss
  • red and blue spectra of Iota Ori at Leoncito Observatory in september 97 and in sept 96 by D. Ballereau and J. Chauville
  • a series of high S/N spectra (R=20000) of the H alpha line in the spectrum of Iota Orionis around the periastron passage of March 1997 (February 25 - March 2) by G. Rauw and J.-M.Vreux. A postscript version of the calibrated spectra is available from Gregor (file size about 614 kbytes).
  • UBV monitoring of Iota Ori via automatic telescope by S. Marchenko and co-workers. They will post the light curve sometime in January 1998.
  • T. Eversberger obtained 12 spectra on sept 27 (including 4 spectra in Stokes V).

  XMEGA members should see the "Iota Ori X-File" for more information

• WR140. We have an ongoing campaign to use the ASCA satellite to obtain 2 spectra per year of the WR+O colliding wind binary WR140, primarily to test the disk model of Becker and White.

  STATUS: 2 observations were obtained in 1997. Observations for 1998 have been approved.

  Coordinated Observations:(XMEGA members should see the "WR140 X-FILE" for more information)

• Carina Nebula. We currently have been granted a 300 ksec observation of the Carina Nebula with the ROSAT HRI to extend the X-ray luminosity function to lower mass stars, to produce a complete X-ray lightcurve of the colliding-wind binary HD 93205, and to resolve the core emission of the peculiar X-ray variable LBV Eta Car

  STATUS:

  • Scheduled in HRI 1st-half long-term timeline
  • the 1st 47 ksec worth of HRI data were obtained in the interval 23-Dec-97 to 30-Jan-98. These data are available via anonymous ftp at ftp://legacy.gsfc.nasa.gov/rosat/data/hri/processed_data/200000/rh202331n00/
  • The revised ROSAT AO8 schedule, covering the Aug1998 to Dec 1998 interval, was released on 15-Sep-1998. The schedule of XMEGA HRI observations of the Carinae Nebula region is available here.
  • Additional data is available for XMEGA Members - see the "Carina Nebula X-File"

• Eta Car. We have been alloted observing time with ASCA to monitor changes in the X-ray spectrum of Eta Carinae during the next "shell event" and afterwards.

  STATUS:

  • These observations were scheduled as follows:

          Name       RA(2000)   DEC(2000)  Seq_num  OBSERVE DURATIO     STATUS
                    (hh mm ss.) (o  '  ")           (YY.DD)  (sec)
      -------------+-----------+---------+---------+-------+-------+-------------
      ETA CAR/PERI  10 45 42.7  -59 39 24  26033000  97.358 113184.  PROCESSED
      ETA CAR/POST  10 44 21.8  -59 41 18  26034000  98.197  63040.  PROCESSED
    

    The first observation listed was obtained in the depths of the X-ray minima and represents the best measurement of the 2-10 keV emission at minimum; the second observation was obtained on Jul 15 1998 when the X-ray flux was recovering.
  • The data are available, and a preliminary report is in preparation; Contact Mike Corcoran at corcoran@barnegat.gsfc.nasa.gov for more information.

• HD 159176. We have been granted time to observe the massive O-star binary HD 159176 with the ROSAT HRI to determine the level of variability in the X-ray emission over 2 orbital cycles.

  STATUS:

  • The revised ROSAT AO8 schedule, covering the Aug1998 to Dec 1998 interval, was released on 15-Sep-1998. The schedule of XMEGA HRI observations of HD 159176 is available here.