Kuehnel: Created page with " * persistent High Mass X-ray Binary * discovered by the Uhuru survey in 1971 () * famous source with a long spin-down, torque reversal to spin-up in..."

2018-04-18T09:56:54Z

Created page with " * persistent High Mass X-ray Binary * discovered by the Uhuru survey in 1971 (<ref name="Giacconi71" />) * famous source with a long spin-down, torque reversal to spin-up in..."

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* persistent High Mass X-ray Binary
* discovered by the Uhuru survey in 1971 (<ref name="Giacconi71" />)
* famous source with a long spin-down, torque reversal to spin-up in 2003, and a another torque reversal back to spin-down in 2007.
* investigated a lot with INTEGRAL and RXTE, a little with Suzaku (<ref name="Rivers10a" />). XMM data exist but are not published.
* CRSF at 18 and 38keV found in BeppoSAX, fundamental line confirmed with Suzaku, but for 1. harmonic S/N too low.
* '''Coordinates''' : RA 19h 09' 37.9" , DEC +09° 49' 49"
* '''Magnetic field strength''': ~2.1x1012 G (<ref name="Cusumano98b" />)

= Orbit =
'''Orbital period'''* : 8.3753(1) days 
'''Eccentricity'''* : 0.28(4) 
'''Orbital epoch'''* : 50134.76(6) MJD 
'''Longitude of periastron'''* : 330(7)° 
'''Projected semimajor axis length'''* : 83(2) lt-s 

* From (<ref name="IntZand98" />)

= Companion =
'''Typ'''* : O8–O9 Ia supergiant (Teff = 30500 K, R = 26 Rsun, L = 5x105 Lsun, D > 5 kpc) 
'''Mass loss rate (stellar wind)'''* : 7x10-6 Msun yr-1 

* From (<ref name="Fritz06" />)

= Accretion =
* wind driven accretion (close orbit, high mass loss of the companion)
* wind & stream accretion (suggested by (<ref name="Kostka10" />)), explaining the double peaked lightcurve (see plot below):

[[File:stream_lc_leahy10.png|250px]]
Plot left shows the double peaked light curve folded onto the orbital period and a zero phase at periastron based on data from the RXTE All-Sky Monitor. Plot right shows the binary geometry including the mid-line of the stream (dashed line) and neutron star (filled circle) on its orbit (dotted line) around the companion star (open circle) at four orbital phases: 0.15 (top-left), 0.35 (top-right), 0.6 (bottom-left) and 0.95 (bottom-right)

[[File:stream-model_leahy10.png|250px]]

= Pulsation =
'''Pulse profile''' : 

* Pulse period = ~441 s with long periods of constant Pdot interrupted by sudden torque reversals.

[[File:history_line.png|350px]]
Plot (<ref name="Sahiner11" />) shows the pulse period history. Section E & D: Pdot = +0.230 s yr-1 dropping to Pdot = +0.115 s yr-1 in the end Section C: Pdot = -0.158 s yr-1 (after torque reversal) Section A: Pdot = 0.226 s yr-1

'''References'''

4U 1907+09 - Revision history

Kuehnel: Created page with " * persistent High Mass X-ray Binary * discovered by the Uhuru survey in 1971 () * famous source with a long spin-down, torque reversal to spin-up in..."