1A 1118-616

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Also known as: 2E 1118.7-6138 [SIMBAD]

Monitoring data: RXTE/ASM Swift/BAT Fermi/GBM pulsed flux

Coordinates

RA 11h 20m 57.215s, Dec -61° 55' 00.29"
RA 170.238 , Dec -61.916747
l 292.4986 , b -00.8918


Binary system

Distance is estimated to be 5±2 kpc [1].

Discovered during an outburst in 1974 by Ariel-5 [2]. Only 3 outburst observed: 1974 [2], 1992 [3] and 2009 [4] [5]

Orbit

Parameter Value Unit Reference
Porb 24.0±0.4 days [6]
T π/2 54845.37±0.4 MJD [6]
a sin i 54.85±1.4 lt-sec [6]
e 0.0 [6]

Note: Due to the fact that the source was only observed for short periods throughout the outbursts, the orbital solutions were not constrained prior to [6]. The eccentricity was fixed to 0 in the orbit determination of the orbital solution [6].

Optical Companion

The optical counterpart was identified as the Be-star Hen 3−640/Wray 793 [7] and classified as an O9.5IV-Ve star with strong Balmer emission lines indicating an extended envelope [1]. [3] showed a strong correlation between the strength of the Hα emission line and the X-ray activity.

Pulsar

The pulse period was determined during the first outburst at 405.3¬±0.6s [8]. In the second outburst the pulse period was measured with ~406.5s and a change of of∼−0.016 s/day. [4] measured a pulse period of 407.719s with a change of ~0.04s/day during the outburst in 2009.

Available data

2009 Outburst

  • RXTE: multiple observations throughout the outburst [4] [6]
  • INTEGRAL: One observation a few weeks after the main peak
  • Suzaku: 2 Observations: one in the peak, one after the outburst [5]


References

  1. 1.0 1.1 Cite error: Invalid <ref> tag; no text was provided for refs named JanotPacheco81
  2. 2.0 2.1 Cite error: Invalid <ref> tag; no text was provided for refs named Eyles75
  3. 3.0 3.1 Cite error: Invalid <ref> tag; no text was provided for refs named Coe94A
  4. 4.0 4.1 4.2 Cite error: Invalid <ref> tag; no text was provided for refs named Doroshenko10
  5. 5.0 5.1 Cite error: Invalid <ref> tag; no text was provided for refs named Suchy11
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Cite error: Invalid <ref> tag; no text was provided for refs named Staubert11
  7. Cite error: Invalid <ref> tag; no text was provided for refs named Chevalier75
  8. Cite error: Invalid <ref> tag; no text was provided for refs named Ives1975