V4641 Sagittarii
File:V4641SgrLightCurve.png A visual band light curve for V4641 Sagittarii, adapted from Goranskij (2001)[1] | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | Template:RA[2] |
| Declination | Template:DEC[2] |
| Apparent magnitude (V) | 9.0 - 14.0[3] |
| Characteristics | |
| Spectral type | B9III[4] |
| Variable type | HMXB/BHXB/XN+ELL+E[3] |
| Astrometry | |
| Proper motion (μ) | RA: −0.734[2] mas/yr Dec.: +0.418[2] mas/yr |
| Parallax (π) | 0.1510±0.0413 mas[2] |
| Distance | Script error: No such module "convert".[4] ly |
| Orbit[4] | |
| Period (P) | Script error: No such module "val". |
| Semi-major axis (a) | Script error: No such module "val". |
| Inclination (i) | Script error: No such module "val".° |
| Periastron epoch (T) | Script error: No such module "val". |
| Semi-amplitude (K2) (secondary) | Script error: No such module "val". km/s |
| Details[4] | |
| Black hole | |
| Mass | Script error: No such module "val". Template:Solar mass |
| Stellar companion | |
| Mass | Script error: No such module "val". Template:Solar mass |
| Radius | Script error: No such module "val". Template:Solar radius |
| Surface gravity (log g) | Script error: No such module "val". cgs |
| Temperature | Script error: No such module "val". K |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Rotational velocity (v sin i) | Script error: No such module "val". km/s |
| Other designations | |
| Template:Odlist[5] | |
| Database references | |
| SIMBAD | data |
Script error: No such module "Check for unknown parameters".
V4641 Sagittarii is a variable X-ray binary star system in the constellation Sagittarius. It is the source of one of the fastest superluminal jets in the Milky Way galaxy.
In 1999 a violent X-ray outburst revealed it to contain a black hole.[6] At the time, it was considered to be the closest known black hole to Earth, at a distance of approximately Script error: No such module "convert".. Later observations showed it to be much farther away, reported in 2001 to be between 7.4 and Script error: No such module "val".,[7] Script error: No such module "val". in 2014,[4] and around Script error: No such module "val". according to its Gaia Data Release 2 parallax.[2]
The star in the binary system is a late B class giant with a mass about three times that of the Sun. It orbits a black hole about twice as massive every 2.8 days. The star is distorted, which causes variations in its brightness as it orbits and rotates. It is also slightly eclipsed by an accretion disc around the black hole. The system usually does not produce a significant amount of x-rays, but undergoes outbursts when the x-ray luminosity increases due to accretion onto the black hole driving superluminal jets.[7]
V4641 Sgr is a source of ultra-high-energy gamma rays.[8]
References
<templatestyles src="Reflist/styles.css" />
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b c d e f Template:Cite Gaia DR2
- ↑ a b Script error: No such module "citation/CS1".
- ↑ a b c d e Script error: No such module "Citation/CS1".
- ↑ Template:Cite simbad
- ↑ Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
Script error: No such module "Check for unknown parameters".
External links