![]() NGC 1624-2 is the brightest star at the centre of NGC 1624 on the left of this image spanning about one degree. | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Perseus |
Right ascension | 04h 40m 37.276s [1] |
Declination | 50° 27′ 41.04″ [1] |
Apparent magnitude (V) | 11.57 [2] |
Characteristics | |
Evolutionary stage | O-type star |
Spectral type | O7f?cp [3] |
U−B color index | −0.57 [2] [4] |
B−V color index | 0.9 [2] |
Astrometry | |
Proper motion (μ) | RA: 0.025 [1] mas/yr Dec.: 0.108 [1] mas/yr |
Parallax (π) | −0.3521 ± 0.1716 mas [1] |
Distance | 5,152.3 [5] pc |
Details | |
Mass | 34 [5] M☉ |
Radius | 10 [5] R☉ |
Luminosity | 126,000 [5] L☉ |
Surface gravity (log g) | 3.55 [1] cgs |
Temperature | 35,000 [5] K |
Metallicity [Fe/H] | +0.07 [1] dex |
Rotation | 315.98 d [6] |
Rotational velocity (v sin i) | <3 [5] km/s |
Other designations | |
TYC 3350-255-1, ALS 18660, 2MASS J04403728+5027410 | |
Database references | |
SIMBAD | data |
NGC 1624-2 is a massive O-type star located in the star cluster NGC 1624, in the constellation of Perseus, about 16,800 light years away. NGC 1624-2 is notable for being most strongly magnetised O-type star known, [6] with a magnetic field strength of 20 kG, or about 20,000 times the Sun's magnetic field strength. [5] It hosts a large and dense magnetosphere, formed from the interaction between its very strong magnetic field and its dense, radiatively-driven stellar wind, which also absorbs up to 95% of x-rays generated from around the star. [5]
NGC 1624-2 is a very massive, young, blue star no more than 4 million years old. It is an Of?p star a type of highly magnetic star that has unusual emission lines of multiply-ionized carbon and nitrogen. In NGC 1624-2, the carbon emission is particularly extreme. The luminosity class is uncertain because of the unusual spectrum; it is most commonly given as V (main sequence), but has also been given as I (supergiant). [7]
Analysis of its spectral energy distribution with CHORIZOS modelling yields an effective temperature of 35,000 K, a luminosity of 125,900 L☉ (105.1 L☉) and a radius of about 10 R☉. Assuming a log g of 4.0 yields a mass of 34 M☉, but evolutionary models tend towards a current mass of 28 M☉, given the results from the modelling. However, this assumes that NGC 1624-2 is a normal star, while it is not, so it should only be taken as an indication of its true mass. NGC 1624-2 is currently losing mass at a rate of 10−6.8 M☉/year, through a stellar wind with a terminal velocity of 2,875 km/s. [5]
NGC 1624-2 rotates very slowly, only once every 316 days. [6] This slow rotation is typical for very magnetic O-type stars as their magnetic fields slow down their rotation in a process known as magnetic braking, where angular momentum is quickly shed by the stellar wind via the strong magnetic field, which also minimises mass loss throughout the main sequence. [5] [6]
Pismis 24-1, also known as HD 319718, is the brightest star of the open cluster Pismis 24 within the nebula NGC 6357 about 6,500 light-years away. It was once thought to be the most massive star known, but is composed of at least three individual objects, each still among the most luminous and most massive stars known.
HD 93205, or V560 Carinae, is a binary stellar system, in the Carina Nebula in the constellation Carina. It consists of two massive O-stars that revolve around each other in 6 days.
WR 136 is a Wolf–Rayet star located in the constellation Cygnus. It is in the center of the Crescent Nebula. Its age is estimated to be around 4.7 million years and it is nearing the end of its life. Within a few hundred thousand years, it is expected to explode as a supernova.
WR 7 is a Wolf–Rayet star in the constellation of Canis Major. It lies at the centre of a complex bubble of gas which is shocked and partially ionised by the star's radiation and winds.
HD 93250 is a highly luminous hot blue binary star in the Carina Nebula in the constellation Carina.
S Monocerotis, also known as 15 Monocerotis, is a massive multiple and variable star system located in the constellation Monoceros. It is the brightest star in the Christmas Tree open cluster in the area catalogued as NGC 2264.
63 Ophiuchi is an O-type giant star in the constellation Sagittarius, despite its name. During a 2009 survey for companions of massive stars, it was observed using speckle interferometry but no companion was found. The small parallax measurement of 0.91±0.09 mas suggest that this extremely luminous star may be located about 3,600 light-years away. An estimate of the distance based on the strength of the Ca II line yields a more modest value of 2,605 ly (799 pc). The star lies only 0.3° north of the galactic plane.
WR 46 is a Wolf-Rayet star in the constellation of the Southern Cross of apparent magnitude +10.8. It is located at 55 arcmin north of Theta2 Crucis. The star is a member of the distant stellar association Cru OB4, and is around 2,900 parsecs or 9,300 light years from the Solar System.
WR 25 is a binary star system in the turbulent star-forming region the Carina Nebula, about 6,800 light-years from Earth. It contains a Wolf-Rayet star and a hot luminous companion and is a member of the Trumpler 16 cluster. The name comes from the Catalogue of Galactic Wolf–Rayet Stars.
R136c is a star located in R136, a tight knot of stars at the centre of NGC 2070, an open cluster weighing 450,000 solar masses and containing 10,000 stars. At 142 M☉ and 3.8 million L☉, it is the one of the most massive stars known and one of the most luminous, along with being one of the hottest, at over 40,000 K. It was first resolved and named by Feitzinger in 1980, along with R136a and R136b.
WR 24 is a Wolf-Rayet star in the constellation Carina. It is one of the most luminous stars known. At the edge of naked eye visibility it is also one of the brightest Wolf Rayet stars in the sky.
WR 156 is a young massive and luminous Wolf–Rayet star in the constellation of Cepheus. Although it shows a WR spectrum, it is thought to be a young star still fusing hydrogen in its core.
BI 253 is an O2V star in the Large Magellanic Cloud and is a primary standard of the O2 type. It is one of the hottest main-sequence stars known and one of the most-massive and most-luminous stars known.
Theta2 Orionis is a multiple star system in the constellation Orion. It is a few arc minutes from its more famous neighbour the Trapezium Cluster, also known as θ1 Orionis.
WR 3 is a Wolf-Rayet star located around 9,500 light years away from Earth in the constellation of Cassiopeia.
HD 151932, also known as WR 78, is a Wolf-Rayet star located in the constellation Scorpius, close to the galactic plane. Its distance is around 1,300 parsecs away from the Earth. Despite being a blue-colored Wolf-Rayet star, it is extremely reddened by interstellar extinction, so its apparent magnitude is brighter for longer-wavelength passbands. HD 151932 lies about 22′ west of the open cluster NGC 6231, the center of the OB association Scorpius OB1; it is not clear whether it is a part of the association or not. With an apparent magnitude of about 6.5, it is one of the few Wolf-Rayet stars that can be seen with the naked eye.
HD 73882 is a visual binary system with the components separated by 0.6″ and a combined spectral class of O8. One of stars is an eclipsing binary system. The period of variability is listed as both 2.9199 days and 20.6 days, possibly due to the secondary being a spectroscopic binary star.
VFTS 243 is an O7V type main sequence star that orbits a stellar mass black hole. The black hole is around nine times the mass of the Sun, with the blue star being 25 times the mass of the Sun making the star 200,000 times larger than the black hole. VFTS 243 is located in the Large Magellanic Cloud inside NGC 2070 around 160,000 light years from Earth. The binary has an orbital period of 10.4 days.