Collinder 261: X-Ray Source Optical Counterparts from Chandra

107 X-ray sources detected within the half-mass radius of the old open cluster Collinder 261 by the Chandra X-Ray Observatory. The observation, with a 53.8 ks exposure starting November 9, 2009, aimed to uncover close interacting binaries and reached a limiting luminosity of ~4 x 10^29 erg s^-1. The catalog includes a mix of active binaries, candidate cataclysmic variables, and straggler stars, with an estimated 26 sources likely associated with the cluster.

Use Cases

• Classifying X-ray source types (e.g., active binaries, cataclysmic variables) based on optical counterpart identification.
• Studying the X-ray emissivity trend of old open clusters compared to globular clusters and local neighborhoods.
• Analyzing the dynamical effects on binary populations in stellar clusters based on source density and luminosity.
• Investigating stellar 'stragglers' in the color-magnitude diagram of Collinder 261.

Strengths

• Observation reached a specific limiting X-ray luminosity of ~4 x 10^29 erg s^-1 (0.3-7 keV).
• Analysis is based on a deep optical source catalog from the ESO Imaging Survey in B and V bands.
• The cluster's approximate mass is estimated at 6500 solar masses, providing a scale for population studies.
• Observation details are precise, including ObsID 11308, exposure time of 53.8 ks, and instrument mode.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• X-ray analysis was limited to four specific ACIS-I chips (I0, I1, I2, I3), excluding data from S2 and S3 chips due to large positional errors.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Data from the Chandra X-Ray Observatory's Advanced CCD Imaging Spectrometer (ACIS), combined with optical images from the ESO public archive.

Time Range

Observation start date 2009-11-09.

Freshness

Last updated 2026-03-13 18:33:59.908128; freshness should be verified.

Geography

Celestial coordinates centered on J2000.0 RA = 12h 38m 06.0s, Dec = -68° 22' 01".