Discovery of an Optical Counterpart to the Supersoft X-ray Source in the Globular Cluster M3

Abstract

We report the detection, with HST, of an optical counterpart to the transient supersoft X-ray source 1E 1339.8+2837, in the globular cluster M3. The counterpart is found near the faint end of the subgiant branch in the V vs V-I color magnitude diagram, but is extremely bright in U. Variability is detected over a range of timescales suggesting the presence of an accretion disk and perhaps also ellipsoidal variations of the subgiant secondary. The optical colors of the binary are similar to those of cataclysmic variables recently discovered in 47 Tucanae and NGC 6397. We suggest that magnetically channeled accretion may explain the relatively low X-ray luminosity of this source's supersoft state.

arXiv comment11 pages, 3 figures, 2 tables. Accepted for publication in ApJ

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Cited by in corpus (6)

• The MAVERIC Survey: Chandra/ACIS Catalog of Faint X-ray sources in 38 Galactic globular clusters
• The first two transient supersoft X-ray sources in M 31 globular clusters and the connection to classical novae
• Supersoft X-rays reveal a classical nova in the M 31 globular cluster Bol 126
• The MAVERIC Survey: Simultaneous Chandra and VLA observations of the transitional millisecond pulsar candidate NGC 6652B
• Identifications of Faint Chandra Sources in the Globular Cluster M3
• Transient Extremely Soft X-ray Emission from the Unusually Bright CV in the Globular Cluster M3: a New CV X-ray Luminosity Record?