A Multi-wavelength study of 1WGA J1346.5-6255: a new $\gamma$ Cas analog unrelated to the background supernova remnant G309.2-00.6

Abstract

1WGA J1346.5-6255 is a ROSAT X-ray source found within the radio lobes of the supernova remnant (SNR) G309.2-00.6. This source also appears to coincide with the bright and early-type star HD 119682, which is in the middle of the galactic open cluster NGC 5281. The radio morphology of the remnant, consisting of two brightened and distorted arcs of emission on opposite sides of the 1WGA J1346.5-6255 source and of a jet-like feature and break in the shell, led to the suggestion that 1WGA J1346.5-6255/G309.2-00.6 is a young analog of the microquasar SS 433 powering the W50 nebula. This motivated us to study this source at X-ray and optical wavelengths. We here present new Chandra observations of 1WGA J1346.5-6255, archival XMM-Newton observations of G309.2-00.6, and optical spectroscopic observations of HD 119682, in order to search for X-ray jets from 1WGA J1346.5-6255, study its association with the SNR, and test for whether HD 119682 represents its optical counterpart. We do not find evidence for jets from 1WGA J1346.5-6255 down to an unabsorbed flux of 2.6E-13 ergs/cm2/s (0.5-7.5 keV), we rule out its association with G309.2-00.6, and we confirm that HD 119682 is its optical counterpart. We derive a distance of 1.2+/-0.3 kpc, which is consistent with the distance estimate to NGC 5281 (1.3+/-0.3 kpc), and much smaller than the distance derived to the SNR G309.2-00.6. We discuss the nature of the source, unveil that HD 119682 is a Be star and suggest it is a new member of the recently proposed group of $\gamma$-Cas analogs. The Chandra and XMM X-ray lightcurves show variability on timescales of hundreds of seconds, and the presence of a possible period of about 1500 s that could be the rotational period of an accreting neutron star or white dwarf in this $\gamma$-Cas analog.

arXiv comment28 pages using emulateapj.cls -- including 3 tables and 16 figures (figs 2, 3, 8, 10, 12, 14, 15 are in color). Fig. 3's resolution is reduced for astro-ph submission only. The original version can be downloaded from http://www.physics.umanitoba.ca/~samar/ms-1WGAJ1346.5-6255.pdf Submitted July 19 (2006), accepted Dec 26 (2006). Minor revisions following referee's report. To appear in the Astrophysical Journal, April 2007

References in corpus (17)

• Towards a unified model for black hole X-ray binary jets
• A new calibration of stellar parameters of Galactic O stars
• A universal radio/X-ray correlation in low/hard state black hole binaries
• The second US Naval Observatory CCD Astrograph Catalog (UCAC2)
• Stellar evolution with rotation X: Wolf-Rayet star populations at solar metallicity
• Supernova Remnants in the Sedov Expansion Phase: Thermal X-Ray Emission
• X-ray astronomy of stellar coronae (Review)
• Discovery of two new persistent Be/X-ray pulsar systems
• Modeling Charge Transfer Inefficiency in the Chandra Advanced CCD Imaging Spectrometer
• New Gamma Cas-like objects: X-ray and optical observations of SAO49725 and HD161103
• G309.2-00.6 and jets in supernova remnants
• Photometric and kinematic studies of open star clusters. III. NGC 4103, NGC 5281, and NGC 4755
• The Remarkable Be Star HD110432
• BeppoSAX survey of Be/X-ray binary candidates
• Two New Ejecta-Dominated Galactic Supernova Remnants: G337.2-0.7 and G309.2-0.6
• Detection of superimposed periodic signals using wavelets
• Multiresolution approach for period determination on unevenly sampled data

Cited by in corpus (11)

• A catalogue of high-mass X-ray binaries in the Galaxy: from the INTEGRAL to the Gaia era
• The X-ray emission of the gamma Cassiopeiae stars
• Core collapse supernova remnants with ears
• The relationship between gamma Cassiopeiae's X-ray emission and its circumstellar environment
• Stellar Binaries That Survive Supernovae
• On the X-ray and optical properties of the Be star HD 110432: a very hard-thermal X-ray emitter
• Chandra and Suzaku observations of the Be/X-ray star HD110432
• A hard and variable X-ray emission from the massive emission line star HD 157832
• X-ray response to disk evolution in two gamma-Cas stars
• Hot thermal X-ray emission from the Be star HD119682
• Massive Stars in Molecular Clouds Rich in High-energy Sources: The Bridge of G332.809-0.132 and CS 78 in NGC 6334