XTE J1946+274
Other Names: 2MASS J19453935+2721555 (Simbad)
Coordinates
RA 19h 45' 39.36", DEC +27° 21' 55.5"
RA 296.414000deg, DEC +27.365417deg
l 63.2072, b +1.3956
Binary system
X-ray Be transient
Distance: 8-10 kpc (Verrecchia et al. 2002)
Orbit
| Parameter | Value | Unit | Reference |
|---|---|---|---|
| Porb | 169.2+-0.6 | days | Wilson et al. (2003) |
| tau | 2,451,558.7+-4 | JD | " |
| a sin i | 640+-120 | lt-sec | " |
| e | 0.33+-0.05 | " | |
| omega | -91+-23 | deg | " |
| i | ? | deg | - |
Optical Companion
Spectral Class : B0-B1 IV-Ve (Verrecchia et al. 2002)
| Parameter | Value | Unit | Reference |
|---|---|---|---|
| Mopt | 10-16 | M⊙ | Verrecchia et al. 2002 |
| B | 18.6 | mag | " |
| H | 12.1 | mag | " |
Available data
- RXTE: PCA, HEXTE, 12 observations (86ks) in Sep/Oct 1998
- RXTE: PCA, HEXTE, 24 observations (129ks) in Mar-Sep 2001
- RXTE: PCA, HEXTE, Jun/Jul and Nov/Dec 2010
- INTEGRAL: Jun/Oct/Nov 2010
- SWIFT: 8 pointings, Nov/Dec 2010
- SUZAKU: Nov 2010
Description
The transient HMXB XTE J1946+274 was discovered 1998 (e.g. Smith & Takeshima 1998). The initial outburst lasted about 3 month, followed by several fainter outbursts seperated by ~80 days (Campana+ 1998). The source was in quiescence from 2001 until 2010, with the in principal same outburst behavior as 1998.
The outburst luminosity in 2010 reached ~120 mCrab (15-50keV) in the first outburst, and ~60 mCrab in the subsequent outbursts.
Spectrum
The spectrum of XTE J1946+274 can be successfully modelled by NPEX (Heindl+ 2001), but also by FDCO + 10keV feature (Mueller+ in prep.). Heindl+ (2001) found a cyclotron line at about 35keV in the initial outburst. The recent outburst in 2010 exhibit a possible cyclotron feature at about 25keV (Mueller+ in prep.)
Pulse Profile
The spin period is about 15.76 s (Mueller+ in prep.) with a spin up (-3.0+-0.3 s/s, Mueller+ in prep), possibly caused by orbital effects. The pulse profile shows a double peaked structure, also seen in, e.g., GRO J1008-57 and 4U 0115+634.