4U 1909+07
Other names : X1908+075 (Simbad, [1])
Coordinates : RA 19h 10' 48.21 , DEC +07° 35' 51.6 (i.e. close to GRS 1915+105 and 4U 1907+09)
Monitoring data: RXTE/ASM Swift/BAT MAXI Fermi/GBM Occultation Project
Binary System
Orbit
Orbital Period: 4.4 days from ASM and RXTE/PCA data ([1], [2])
Strong variation of N_H over the orbit, leads to contstrained inclination of 38°-72° ([2]).
The distance of the binary system was estimated to be ∼7 kpc by [3]. A newer analysis by [4] derives the distance to be 4.85 ± 0.50 kpc.
Companion
Probably an early B-type (B0--B3) star; M_spec = 15±6M⊙ [4]
Description
Pulsations
Pulse Period: ~604sec, changing in a random walk like manner ([2], [5])
Plot shows period measurements from RXTE data ([2]) in red and from INTEGRAL data ([5]) in black).
Pulse profile: strongly energy dependent:
Plot shows pulse profiles from RXTE/PCA in black in panels a-c, a RXTE/HEXTE profile in panel d in black and a INTEGRAL/ISGRI profile in panel d in red ([5]).
Spectrum
Well described with a phabs*(cutoffpl+gauss) model, additional bbody improves χ² esepecially in phase resolved analysis ([5])
Plot panel a shows the RXTE/PCA spectrum in red, RXTE/HEXTE in green, INTEGRAL/ISGRI in blue. Panel b shows residuals without a blackbody component, c with the blackbody ([5]).
Claimed Compton shoulder in Chandra data on the iron Kα line ([6]).
CRSF: none known (RXTE and INTEGRAL data)
Further data
Suzaku 25ksec observations to be done in AO5.
References
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