Loading AI tools
Star in the constellation Crux From Wikipedia, the free encyclopedia
BU Crucis (HD 111934) is a variable star in the open cluster NGC 4755, which is also known as the Kappa Crucis Cluster or Jewel Box Cluster.
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Crux |
Right ascension | 12h 53m 37.62181s[1] |
Declination | −60° 21′ 25.3912″[1] |
Apparent magnitude (V) | 6.80 - 6.90[2] |
Characteristics | |
Spectral type | B2 Ia[3] |
U−B color index | −0.67[4] |
B−V color index | +0.20[4] |
Variable type | Eclipsing?[2] |
Astrometry | |
Radial velocity (Rv) | −17.00[5] km/s |
Proper motion (μ) | RA: −4.643[6] mas/yr Dec.: −1.050[6] mas/yr |
Parallax (π) | 0.4441 ± 0.0330 mas[6] |
Distance | 7,300 ± 500 ly (2,300 ± 200 pc) |
Absolute magnitude (MV) | −7.00[3] |
Details | |
Mass | 29.2[3] M☉ |
Radius | 41.6[3] R☉ |
Luminosity | 275,000[3] L☉ |
Surface gravity (log g) | 2.65[3] cgs |
Temperature | 20,600[3] K |
Rotational velocity (v sin i) | 75[7] km/s |
Age | 5.6[3] Myr |
Other designations | |
Database references | |
SIMBAD | data |
BU Cru is one of the brightest members of the NGC 4775 open cluster, better known as the Jewel Box Cluster.[8] It forms the right end of the bar of the prominent letter "A" asterism at the centre of the cluster. The cluster is part of the larger Centaurus OB1 association and lies about 8,500 light years away.
The cluster, and BU Crucis itself, is just to the south-east of β Crucis, the lefthand star of the famous Southern Cross.
BU Crucis is a B2 bright supergiant (luminosity class Ia). It is 275,000 times the luminosity of the sun, partly due to its higher temperature over 20,000 K, and partly to being forty times larger than the sun. The κ Crucis cluster has a calculated age of 11.2 million years, and BU Crucis itself around five million years.[3]
BU Crucis is a variable star with a brightness range of about 0.1 magnitudes. It is listed as a probable eclipsing binary in the General Catalogue of Variable Stars,[2] but the International Variable Star Index classifies it as an α Cygni variable with a visual magnitude range of 6.82 - 7.01.[10]
Seamless Wikipedia browsing. On steroids.
Every time you click a link to Wikipedia, Wiktionary or Wikiquote in your browser's search results, it will show the modern Wikiwand interface.
Wikiwand extension is a five stars, simple, with minimum permission required to keep your browsing private, safe and transparent.