M 37 Chandra X-Ray Point Source Catalog

Empirical calibrations of the stellar age-rotation-activity relation (ARAR) rely on observations of the co-eval populations of stars in open clusters. The authors used the Chandra X-ray Observatory to study M 37 (NGC 2099), a 500-Myr-old open cluster that has been extensively surveyed for rotation periods (P&lt;sub&gt;rot&lt;/sub&gt;). M 37 was observed almost continuously for five days, for a total of 440.5 ks, to measure stellar X-ray luminosities (L&lt;sub&gt;X&lt;/sub&gt;), a proxy for coronal activity, across a wide range of masses. The cluster&#39;s membership catalog was revisited to calculate updated membership probabilities from photometric data and each star&#39;s distance to the cluster center. The result is a comprehensive sample of 1699 M 37 members: 426 with P&lt;sub&gt;rot&lt;/sub&gt;, 278 with X-ray detections, and 76 with both. The authors calculate Rossby numbers, R&lt;sub&gt;o&lt;/sub&gt;= P&lt;sub&gt;rot&lt;/sub&gt;/tau , where tau is the convective turnover time, and ratios of the X-ray-to-bolometric luminosity, L&lt;sub&gt;X&lt;/sub&gt;/L&lt;sub&gt;bol&lt;/sub&gt;, to minimize mass dependencies in their characterization of the rotation-coronal activity relation at 500 Myr. They find that fast rotators, for which R&lt;sub&gt;o&lt;/sub&gt; &lt; 0.09 +/- 0.01, show saturated levels of activity, with log(L&lt;sub&gt;X&lt;/sub&gt;/L&lt;sub&gt;bol&lt;/sub&gt;) = -3.06 +/- 0.04. For R&lt;sub&gt;o&lt;/sub&gt; &gt;= 0.09 +/- 0.01, activity is unsaturated and follows a power law of the form R&lt;sup&gt;beta&lt;/sup&gt;&lt;sub&gt;o&lt;/sub&gt; , where beta = -2.03 (-0.14, +0.17). This is the largest sample available for analyzing the dependence of coronal emission on rotation for a single-aged population, covering stellar masses in the range 0.4 - 1.3 solar masses, P&lt;sub&gt;rot&lt;/sub&gt; in the range 0.4 - 12.8 days, and L&lt;sub&gt;X&lt;/sub&gt; in the range 10&lt;sup&gt;28.4&lt;/sup&gt; - 10&lt;sup&gt;30.5&lt;/sup&gt; erg s&lt;sup&gt;-1&lt;/sup&gt;. These results make M 37 a new benchmark open cluster for calibrating the ARAR at ages of ~ 500 Myr. The central field of M 37 was observed five separate times between 2011 November 14 20:58 and 2011 November 1915:31 UTC for a total of 440.5 ks with the Advanced CCD Imaging Spectrometer (ACIS). The four ACIS-I chips and the ACIS-S3 chip were used in Very Faint telemetry mode to improve the screening of background events and thus increase the sensitivity of ACIS to faint sources. The exposure-weighted average aimpoint of the 16.9 x 16.9 arcmin&lt;sup&gt;2&lt;/sup&gt; ACIS-I field of view is RA = 05&lt;sup&gt;h&lt;/sup&gt; 52&lt;sup&gt;m&lt;/sup&gt; 17.86&lt;sup&gt;s&lt;/sup&gt;,Dec = +32&lt;sup&gt;o&lt;/sup&gt; 33&#39; 48.23&quot; (J2000). The pitch angle for four observations was 103 degrees; due to scheduling constraints, it was 253 degrees for the fifth. Table 1 in the reference paper provides the basic information for the 5 Chandra observations and Figure 1 in that paper shows their footprints superimposed on a 40&#39; x 40&#39; i&#39; image centered on M 37 obtained by Hartman et al. (2008, ApJ, 675, 1233, hereafter HA08) with the Megacam on the MMT telescope. This HEASARC table contains all of the data from Table 3 of the reference paper, the M 37 Chandra catalog of 774 X-ray sources, and the data from Table 5, the catalog of optical objects, for those objects which have been identified as optical counterparts to the X-ray sources. It does not contain entries for those optical objects in Table 5 which lack X-ray counterparts. This online catalog was created by the HEASARC in December 2015 based on machine-readable versions of tables 3 and 5 from the paper which were obtained from the ApJ website. This is a service provided by NASA HEASARC .

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Organization: National Aeronautics and Space Administration