X Per
Other Names: V* X Per Simbad, 4U 0352+309
Monitoring data: RXTE/ASM Swift/BAT MAXI
Coordinates
RA 03h 55' 23.077", DEC +31° 02' 45.01"
RA 58.8461542deg, DEC -31.0458361deg
l 163.0814, b -17.1362
Binary system
Distance: 0.95(20) kpc ([1])
Orbit
| Parameter | Value | Unit | Reference |
|---|---|---|---|
| Porb | 250 | days | [2] |
| tau | MJD | ||
| a sin i | 2 | AU | [2] |
| e | 0.11 | [2] | |
| omega | deg |
Description
4U 0352+309 is a persistent X-ray source in a binary with the Be-type star X Persei. It is believed that the neutron strar accretes material from the wind of either the Be companion atmosphere (fast, low-density) or its outskirts, i.e. the Be-disk (low, dense). A good summary and discussion about the different scenarios can be found in [3].
Spectrum
The spectrum of 4U 0352+309 is unusually hard and is detectable up to 200 keV in ISGRI. Earlier models describe the spectrum by a combination of two powerlaws ([4]) or a black body with an additional hard powerlaw ([5]). The later also requires an absorption like feature around 30 keV, which was interpreted as CRSF. A recent analysis by [3] showed, however, that the unusual spectrum can be described well by two thermal Comptonization models. Thereby the claimed cyclotron line is no longer needed. In addition, the used model, the relatively long pulse period of 837 s and by comparing to 4U 2206+54 may suggest the neutron star to have a magnetic field in the order of 1014 G, thus in the magnetar range.
References
- ↑ Telting, J. H., Waters, L. B. F. M., Roche, P., et al., 1998, MNRAS, 296, 785 (NASA ADS)
- ↑ 2.0 2.1 2.2 Delgado-Marti, H., Levine, A. M., Pfahl, E., Rappaport, S. A., 2001, ApJ, 546, 455 (NASA ADS)
- ↑ 3.0 3.1 Doroshenko, V., Santangelo, A., Kreykenbohm, I., Doroshenko, R., 2012, A&A, accepted (NASA ADS)
- ↑ Di Salvo, T., Burderi, L., Robba, N. R., Guainazzi, M., 1998, ApJ, 509, 897 (NASA ADS)
- ↑ Coburn, W., Heindl, W.A., Gruber, D.E., et al., 2001, ApJ, 552, 738 (NASA ADS)