Location of BZ Crucis (circled). The other star shown overlapping/underlying the dark nebula is HD 109000 (HR 4771) which is a red/brown star about half the distance to the nebula, having parallax of 12.8 ± 0.05 thus about 250 light years away
[1] | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Crux |
Right ascension | 12h 42m 50.2656s [1] |
Declination | −63° 03′ 31.048″ [1] |
Apparent magnitude (V) | 5.24 - 5.45 [2] |
Characteristics | |
Spectral type | B1IVe [3] |
U−B color index | −0.82 [4] |
B−V color index | +0.27 [4] |
Variable type | γ Cas [2] |
Astrometry | |
Radial velocity (Rv) | +35 [5] km/s |
Proper motion (μ) |
RA: −12.512
[1]
mas/
yr Dec.: −3.984 [1] mas/ yr |
Parallax (π) | 2.3834 ± 0.1228 mas [1] |
Distance | 1,370 ± 70
ly (420 ± 20 pc) |
Absolute magnitude (MV) | −2.56 [6] |
Details | |
Mass | 9.6 [3] M☉ |
Radius | 6.5±1.2 [7] R☉ |
Luminosity | 1,153 [1] L☉ |
Surface gravity (log g) | 3.5–3.9 [3] cgs |
Temperature | 22,510–25,000 [3] K |
Rotational velocity (v sin i) | 300–400 [3] km/s |
Other designations | |
Database references | |
SIMBAD | data |
HD 110432 is a Be star in the south-east of Crux, behind the center of the southern hemisphere's dark Coalsack Nebula. It has a stellar classification of B1IVe, which means it is a subgiant star of class B that displays emission lines in its spectrum. This is a variable star of the Gamma Cassiopeiae type, indicating it is a shell star with a circumstellar disk of gas about the equator, and has the variable star designation BZ Crucis. It is not known to be a member of a binary system, although it is probably a member of the open cluster NGC 4609. This star is moderately luminous in the X-ray band, with a variable energy emission of 1032–33 erg s−1 in the range 0.2−12 keV. The X-ray emission may be caused by magnetic activity, or possibly by accretion onto a white dwarf companion. [3]
The distance of 388 pc published in the 2007 new Hipparcos reduction is over twice the distance of the Coalsack Nebula. [10] The distance from Gaia Data Release 2 is even further at 420 pc. [1]
Location of BZ Crucis (circled). The other star shown overlapping/underlying the dark nebula is HD 109000 (HR 4771) which is a red/brown star about half the distance to the nebula, having parallax of 12.8 ± 0.05 thus about 250 light years away
[1] | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Crux |
Right ascension | 12h 42m 50.2656s [1] |
Declination | −63° 03′ 31.048″ [1] |
Apparent magnitude (V) | 5.24 - 5.45 [2] |
Characteristics | |
Spectral type | B1IVe [3] |
U−B color index | −0.82 [4] |
B−V color index | +0.27 [4] |
Variable type | γ Cas [2] |
Astrometry | |
Radial velocity (Rv) | +35 [5] km/s |
Proper motion (μ) |
RA: −12.512
[1]
mas/
yr Dec.: −3.984 [1] mas/ yr |
Parallax (π) | 2.3834 ± 0.1228 mas [1] |
Distance | 1,370 ± 70
ly (420 ± 20 pc) |
Absolute magnitude (MV) | −2.56 [6] |
Details | |
Mass | 9.6 [3] M☉ |
Radius | 6.5±1.2 [7] R☉ |
Luminosity | 1,153 [1] L☉ |
Surface gravity (log g) | 3.5–3.9 [3] cgs |
Temperature | 22,510–25,000 [3] K |
Rotational velocity (v sin i) | 300–400 [3] km/s |
Other designations | |
Database references | |
SIMBAD | data |
HD 110432 is a Be star in the south-east of Crux, behind the center of the southern hemisphere's dark Coalsack Nebula. It has a stellar classification of B1IVe, which means it is a subgiant star of class B that displays emission lines in its spectrum. This is a variable star of the Gamma Cassiopeiae type, indicating it is a shell star with a circumstellar disk of gas about the equator, and has the variable star designation BZ Crucis. It is not known to be a member of a binary system, although it is probably a member of the open cluster NGC 4609. This star is moderately luminous in the X-ray band, with a variable energy emission of 1032–33 erg s−1 in the range 0.2−12 keV. The X-ray emission may be caused by magnetic activity, or possibly by accretion onto a white dwarf companion. [3]
The distance of 388 pc published in the 2007 new Hipparcos reduction is over twice the distance of the Coalsack Nebula. [10] The distance from Gaia Data Release 2 is even further at 420 pc. [1]