A Chandra Observation of the Intermediate Polar Binary AR Scorpii
ATel #12464; Maya Bode Mathur (Commonwealth School), Rohan Abichandani (Commonwealth School), Antonella Fruscione (CfA | Harvard & Smithsonian), Jeremy J. Drake (CfA | Harvard & Smithsonian), Nicholas P. Lee (CfA | Harvard & Smithsonian), Kenny Glotfelty (CfA | Harvard & Smithsonian)
on 1 Feb 2019; 23:01 UT
Credential Certification: Jeremy J. Drake (jdrake@cfa.harvard.edu)
Subjects: X-ray, Binary, Star, Variables
We report X-ray emission from the intermediate polar binary system AR Scorpii observed with the Chandra X-Ray Observatory ACIS-S CCD. This confirms a previous X-ray detection by the XMM-Newton observatory (Tanaka, J et. al, 2018, ApJ, 853, 106). AR Scorpii is an unusual binary system composed of a magnetic white dwarf displaying pulsed emission and an M dwarf star and was observed by Chandra on 2017 June 23 for 25 ksec. We measured 4255 +/- 65 counts centered around the position of the source (RA: 16:21:47.3 Dec: -22:53:11) within a circle of 5 arcsec radius. The count rate was 0.169 +/- 0.004 c/s with a 90% confidence. We extracted a spectrum of the source and fit it with a two-temperature MEKAL model with fixed interstellar hydrogen column density of 3.4e^20 atoms/cm^2 and metal abundances equal to 0.62 of solar values as found by Tanaka et al (2018) based on XMM-Newton observations obtained on 2016 September 19. We obtained temperatures of kT = 3.96 (+0.36/-0.21) and 9.75e^-5 (+6.7/-5.4) keV respectively. The hotter dominant component is softer than the one reported for the earlier XMM observation. There was no obvious modulation at the 8.46 mHz WD spin/orbital beat period as noted by Tanaka et al, but we found periodicities at 3.38, 3.70, 3.45, and 5.00 hours with roughly equal power. We calculated an unabsorbed model flux for this source of 2.68 (+0.07/-0.06) e^-12 erg/cm2/s in the bandpass 0.5-7 keV.
