1RXS J180431.1-273932
Coordinates
RA 18h 04m 31.2s, Dec -27° 39' 32"
RA 271.130000 , Dec -27.658889
l 003.2029 , b -02.9474
Binary System
Distance estimated to be approximately 10 kpc by [1].
Orbit
| Parameter | Value | Unit | Reference |
|---|
Optical Companion
Name: OGLE IIDIABUL-SC35-4278
Pulsating red giant with a main period of 20.26 days and an amplitude of 0.02 mag in the I band.
Spectral Class: M6III ([1]).
Available data
- Chandra: 7' off-axis pointing (9.9ksec, Feb 2004), observation of MACHO-96-BLG-5
- XMM-Newton: 7' off-axis pointing (100ksec, Oct 2005), observation of MACHO-96-BLG-5 (see. Nucita et al, 2007 )
- Swift: 22' off-axis pointing (6ksec XRT, Jun 2010), observation of NGC6540
Description
1RXS J180431.1-273932 is characterized by regular pulses making it a possible neutron star. [1] identified an optical counterpart (The M6III red-giant OGLE II DIA BULGE-SC35 4278) allowing a distance of ~10 kpc to be estimated. From this distance [1] calculated an X-ray luminosity of ~< 6 × 1034 erg s−1, which is consistent with the typical X-ray luminosity of a Symbiotic X-ray Binary.
Flux
The X-ray flux in the 0.2-10 keV energy band is 5.4 × 10-12 erg s−1 cm−2 ([1]).
Spectrum
The spectrum can be described by a power law with a photon index of ~1 and a Gaussian line at 6.6 keV ([1]).
Pulse Profile
The source is characterized by regular pulses so that it is most likely a neutron star. A modulation of 494.1 ± 0.2 s (3σ error) was found with a confidence level of >99%. Evidence of variability is also present, since the data show a rate of change in the signal of ∼−7.7 × 10−4 counts s−1 h−1 ([1]).
References