Vela X-1

Database links to Vela X-1

Data from Vela X-1 Massive X-ray binary star
Constellation	Sails of the ship
Position Epoch : J2000.0 Equinox : J2000.0
Right ascension	9020709 ^h 02 ^m 07 ^s
declination	1596683−40 ° 33 ′ 17 ″
Double star system
Type	Massive X-ray binary star (HMXB)
distance	1.9 ± 0.2 k pc (approximately 6.2 ± 0.650 k Lj )
Period of circulation	8,964 d
Medium distance	0.8 R _☉
Optical / stellar component
Apparent brightness (V-band)	6,926 mag
Spectral class	B0.5 Ib
Surface temperature	31,500 K (super giant)
radius	approx. 11.2 R _☉
Dimensions	1.86 ± 0.32 (neutron star), 23.5 (supergiant) M _☉
Catalog names
Supergiant: GP Vel, HD 77581, SAO 220767, HIP 44368, CPD -40 ° 3072, CD -40 ° 4838; X-ray source: 1XRS 09002-403, 1RXS J090207.0-403311, 4U 0900-40

Vela X-1 is a pulsating , massive X-ray binary star in the constellation Sails of the Ship .

discovery

Vela X-1 was detected in 1971 in the course of an investigation of the galactic plane as a source of X-rays by the satellite Uhuru in the constellation of the ship's sail (lat. Vela ). The name arises from the fact that this is the first X-ray object discovered in the constellation of the same name.

Vela X-1 should not be confused with the Vela pulsar (PSR B0833-45), which is a strong gamma ray source - but only a comparatively weak source of x-rays.

description

The system, about 6200 light years away, consists of the X-ray source 4U 0900-40, a neutron star , and the blue supergiant HD 77581, which orbit each other at a distance of only 0.8 solar radii in just under 9 days. The neutron star is covered by HD 77581 from an observer on Earth for about two days. Vela X-1 is a typical representative of an X-ray binary star of the HMXB ( High mass X-ray binaries ) category .

The X-ray emission of the neutron star is caused by the capture and accretion of matter from the stellar wind of its companion, which heats up to a few million degrees and gives off energy in the form of X-rays. X-ray spectroscopic examinations showed that the stellar wind is inhomogeneous and consists of several "lumps" of high density within a lighter, strongly ionized component. The mass of the neutron star is around 1.9 solar masses, making it one of the most massive among those known to date (cf. the neutron star in PSR J0348 + 0432 ). The companion star has an estimated mass of 23.5 solar masses. The rotation time is around 282 seconds. Long-term observations show a fluctuation in the rotation frequency caused by the uneven material accretion.

HD 77581

HD 77581 and clearly recognizable bow shock wave. The neutron star is not visible.

The blue super giant HD 77581 has a high intrinsic movement of ≳ 7 mas / yr. Its space velocity is ≳ 90 km / s. It is therefore classified as a fast runner ( runaway star ). Due to the supersonic movement through the interstellar matter , the star wind forms clear shock fronts ( bow shock waves ) with filament structures.

From the speed and direction it can be concluded that HD 77581 has its origin in the stellar association Vela OB1 , about 1.9 kpc from Earth , from which it was catapulted by a supernova about 2.5 (1–3) million years ago . This coincides with the presumed supernova point in time of the neutron star's predecessor, which would make this a possible trigger. According to the hypotheses of the astronomers Fritz Zwicky and Adriaan Blaauw ( Blaauw scenario ), supernova explosions in binary star systems can accelerate the partner to high speeds, but the two stars remain bound to each other.

Future development

According to hypotheses, the system could develop into a Thorne--ytkow object through the constant transfer of matter and the resulting approach - a state in which the two stars are merged into one. After the hydrogen-rich envelopes were removed by the stellar wind, the result would be a Wolf-Rayet-Thorne-Żytkow object .

Web links

Vela X-1 in the wiki of the Dr. Remeis observatory .

Individual evidence

↑ ^a ^b ^c ^d ^e Manfred Hanke: Studying the stellar wind in the Vela X-1 system with XMM-Newton / RGS (PDF) ESAC 2007
↑ HD 77581 (HIP 44368) ( Memento from April 2, 2015 in the Internet Archive ) on astrostudio.org
^ Riccardo Giacconi et al .: An X-Ray Scan of the Galactic Plane from UHURU . In: Astrophysical Journal Letters , 165, 1971, L27-L35 bibcode : 1971ApJ ... 165L..27G .
↑ NASA: Astronomy Picture of the Day - Runaway Star HD 77581 (with picture)
↑ ^a ^b ^c ^d Lex Kaper: Discovery of a bow shock around Vela X-1 . November 4, 1996, arxiv : astro-ph / 9611017 (English).
↑ B. Cameron Reed: Vela OB1: PROBABLE NEW MEMBERS AND HERTZSPRUNG-RUSSELL DIAGRAM . In: Astronomical Journal . April 2000. Retrieved March 12, 2015.
^ ^A ^b F. C. Lazaro, MJ Arevalo: Binary Stars: Selected Topics on Observations and Physical Processes: Lectures Held at the Astrophysics School XII Organized by the European Astrophysics Doctoral Network (EADN) in La Laguna, Tenerife, Spain, 6-17 September 1999 . Springer Science & Business Media, 2001, ISBN 978-3-540-41256-4 , pp. 266, 268 (English).

[xmm-1] Manfred Hanke: Studying the stellar wind in the Vela X-1 system with XMM-Newton / RGS (PDF) ESAC 2007

[astrostudio-2] HD 77581 (HIP 44368) ( Memento from April 2, 2015 in the Internet Archive ) on astrostudio.org

[3] Riccardo Giacconi et al .: An X-Ray Scan of the Galactic Plane from UHURU . In: Astrophysical Journal Letters , 165, 1971, L27-L35 bibcode : 1971ApJ ... 165L..27G .

[4] NASA: Astronomy Picture of the Day - Runaway Star HD 77581 (with picture)

[kaper-5] Lex Kaper: Discovery of a bow shock around Vela X-1 . November 4, 1996, arxiv : astro-ph / 9611017 (English).

[6] B. Cameron Reed: Vela OB1: PROBABLE NEW MEMBERS AND HERTZSPRUNG-RUSSELL DIAGRAM . In: Astronomical Journal . April 2000. Retrieved March 12, 2015.

[lazaro-7] A ^b F. C. Lazaro, MJ Arevalo: Binary Stars: Selected Topics on Observations and Physical Processes: Lectures Held at the Astrophysics School XII Organized by the European Astrophysics Doctoral Network (EADN) in La Laguna, Tenerife, Spain, 6-17 September 1999 . Springer Science & Business Media, 2001, ISBN 978-3-540-41256-4 , pp. 266, 268 (English).