arXiv subjects

M. Corcoran

Publications and source records attributed to M. Corcoran.

21 records · Page 2Linked to original sources

arXiv2002

The massive double-lined O-type binary HD 165052

We present a new optical spectroscopic study of the O-type binary HD 165052 based on high- and intermediate-resolution CCD observations. We re-investigated the spectral classification of the binary components, obtaining spectral types of O6.5 V and O7.5 V for the primary and secondary, respectively, finding that both stars display weak C {\sc iii} $\lambda5696$ emission in their spectra. We also determined a radial-velocity orbit for HD 165052 with a period of 2.95510 $\pm$ 0.00001 d, and semiamplitudes of 94.8 and 104.7 $\pm$ 0.5 km s$^{-1}$, resulting in a mass ratio $Q = 0.9$. From a comparison with previous radial-velocity determinations, we found evidence of apsidal motion in the system. Several signatures of wind-wind collision, such as phase-locked variability of the X-ray flux and the Struve-Sahade effect, are also considered. It was also found that the reddening in the region should be normal, in contrast with previous determinations.

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arXiv2001

Optical spectroscopy of X-Mega targets in the Carina Nebula. II. The massive double-lined O-type binary HD 93205

A new high-quality set of orbital parameters for the O-type spectroscopic binary HD93205 has been obtained combining echelle and coude CCD observations. The radial velocity orbits derived from the HeII 4686 A (primary component) and HeI 4471 A (secondary component) absorption lines yield semiamplitudes of 133 +/- 2 and 314 +/- 2 km/s for each binary component, resulting in minimum masses of 31 and 13 Msol (q = 0.42). We also confirm for the binary components the spectral classification of O3V+O8V previously assigned. Assuming for the O8V component a ``normal'' mass of 22 - 25 Msol we would derive for the primary O3V a mass of ``only'' 52 - 60 Msol and an inclination of about 55 degrees for the orbital plane. We have also determined for the first time a period of apsidal motion for this system, namely 185 +/- 16 years using all available radial velocity data-sets of HD 93205 (from 1975 to 1999). Phase-locked variations of the X-ray emission of HD 93205 consisting of a rise of the observed X-ray flux near periastron passage, are also discussed.

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arXiv2001

Early Chandra X-ray Observations of Eta Carinae

Sub-arcsecond resolution Chandra observations of Eta Carinae reveal a 40 arcsec X 70 arcsec ring or partial shell of X-ray emission surrounding an unresolved, bright, central source. The spectrum of the central source is strongly absorbed and can be fit with a high-temperature thermal continuum and emission lines. The surrounding shell is well outside the optical/IR bipolar nebula and is coincident with the Outer Shell of Eta Carinae. The X-ray spectrum of the Shell is much softer than that of the central source. The X-ray Shell is irregular and only correlates well with optical features where a bright X-ray knot coincides with a bright feature of the Outer Shell. Implications for the binary model of the central source are discussed.

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