Large Magellanic Cloud - X-ray Sources

X-ray Sources

No X-rays above background were observed from the Magellanic Clouds during the September 20, 1966, Nike Tomahawk flight. A second Nike Tomahawk rocket was launched from Johnston Atoll on September 22, 1966, at 17:13 UTC and reached an apogee of 160 km, with spin-stabilization at 5.6 rps. The LMC was not detected in the X-ray range 8-80 keV.

Another Nike Tomahawk was launched from Johnston Atoll at 11:32 UTC on October 29, 1968, to scan the LMC for X-rays. The first discrete X-ray source in Dorado was at RA 05h 20m Dec -69°, and it was the Large Magellanic Cloud. This X-ray source extended over about 12° and is consistent with the Cloud. Its emission rate between 1.5-10.5 keV for a distance of 50 kpc is 4 x 1038 ergs/s. An X-ray astronomy instrument was carried aboard a Thor missile launched from Johnston Atoll on September 24, 1970, at 12:54 UTC and altitudes above 300 km, to search for the Small Magellanic Cloud and to extend previous observations of the LMC. The source in the LMC appeared extended and contained the star ε Dor. The X-ray luminosity (L_x) over the range 1.5–12 keV was 6 × 1031 W (6 × 1038 erg/s).

The Large Magellanic Cloud (LMC) is in the constellations Mensa and Dorado. LMC X-1 (the first X-ray source in the LMC) is at RA 05h 40m 05s Dec -69° 45′ 51″, and is a high mass X-ray binary source (HMXB). Of the first five luminous LMC X-ray binaries: LMC X-1, X-2, X-3, X-4, and A 0538-66 (detected by Ariel 5 at A 0538-66); LMC X-2 is the only one that is a bright low-mass X-ray binary system (LMXB) in the LMC.

DEM L316 in the Large Magellanic Cloud consists of two supernove remnants. Chandra X-ray spectra show that the hot gas shell on the upper left contains a high abundance of iron. This implies that the upper left SNR is the product of a Type Ia supernova. The much lower iron abundance in the lower SNR indicates a Type II supernova.

A 16 ms X-ray pulsar is associated with SNR 0538-69.1. SNR 0540-697 was resolved using ROSAT.