Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Dorado |
Right ascension | 5h 5m 55.51147s [2] |
Declination | −67° 53′ 10.9330″ [2] |
Apparent magnitude (V) | 8.99 - 9.22 [3] |
Characteristics | |
Spectral type | A3Ia+ [4] |
U−B color index | −0.29 [5] |
B−V color index | +0.14 [5] |
Variable type | α Cygni [6] |
Astrometry | |
Radial velocity (Rv) | 255.959 [7] km/s |
Proper motion (μ) | RA: +1.810 [2] mas/yr Dec.: +0.146 [2] mas/yr |
Parallax (π) | 0.0178 ± 0.0137 mas [2] |
Distance | 148,700 ly (45,600 pc) [8] |
Absolute magnitude (MV) | −9.57 [9] |
Details | |
Mass | 20–30 [10] M☉ |
Radius | 419 [11] [lower-alpha 1] 471 [12] [lower-alpha 2] R☉ |
Luminosity | 575,400 [11] L☉ |
Surface gravity (log g) | 0.82±0.21 [4] cgs |
Temperature | 7,763 [11] K |
Metallicity [Fe/H] | −0.38±0.14 [4] dex |
Other designations | |
Database references | |
SIMBAD | data |
HD 33579 is a white/yellow hypergiant and one of the brightest stars in the Large Magellanic Cloud (LMC). It is a suspected variable star.
HD 33579 lies in a part of the Hertzsprung–Russell diagram referred to as the Yellow Evolutionary Void because stars with that combination of luminosity and temperature are extremely unstable. They either expand to become cooler or shed their outer layers completely to become hotter. Yet HD 33579 is relatively stable, hardly even variable. This is thought to be due to its higher mass compared to most stars with similar temperature and luminosity. [4] It has a radius of approximately 650 solar radii, comparable to Betelgeuse and larger than the orbit of Mars. [11]
HD 33579 is an extremely rare type of star currently evolving for the first time through the yellow evolutionary void from being a blue hypergiant to becoming a red hypergiant. This means the star is often referred to as a yellow hypergiant although the spectral type of A3 means it is also described as a white hypergiant. [4]
Although HD 33579 has not been formally listed in the General Catalogue of Variable Stars, analysis of Hipparcos photometry confirmed small amplitude variations in its brightness that had been reported in earlier research. [13] [14] [15] Periods of 620 days and 105 days are found, plus other possible shorter periods. The total amplitude is only around 0.1 magnitudes. [6] A statistical analysis of Hipparcos photometry showed a possible period of 27 days. [16]
HD 90853 is a single star in the southern constellation Carina. It has the Bayer designation s Carinae, while HD 98053 is the identifier from the Henry Draper catalogue. This is a variable star with an apparent visual magnitude that ranges from 3.36 down to 3.51, and thus is bright enough to be visible to the naked eye. It is located at a distance of approximately 1,340 light-years from the Sun based on parallax, and has an absolute magnitude of −4.44. The star is drifting further away with a radial velocity of +9 km/s.
V382 Carinae, also known as x Carinae, is a yellow hypergiant in the constellation Carina. It is a G-type star with a mean apparent magnitude of +3.93, and a variable star of low amplitude.
V509 Cassiopeiae is one of two yellow hypergiant stars found in the constellation Cassiopeia, which also contains Rho Cassiopeiae.
Omicron1 Centauri is a star in the constellation Centaurus. It is approximately 10,000 light years from Earth.
A yellow hypergiant (YHG) is a massive star with an extended atmosphere, a spectral class from A to K, and, starting with an initial mass of about 20–60 solar masses, has lost as much as half that mass. They are amongst the most visually luminous stars, with absolute magnitude (MV) around −9, but also one of the rarest, with just 20 known in the Milky Way and six of those in just a single cluster. They are sometimes referred to as cool hypergiants in comparison with O- and B-type stars, and sometimes as warm hypergiants in comparison with red supergiants.
HD 37974 a variable B[e] hypergiant in the Large Magellanic Cloud. It is surrounded by an unexpected dust disk.
V810 Centauri is a double star consisting of a yellow hypergiant primary and blue giant secondary. It is a small amplitude variable star, entirely due to the supergiant primary which is visually over three magnitudes brighter than the secondary. It is the MK spectral standard for class G0 0-Ia.
HD 74180 is a single star in the constellation Vela. It is a yellow-white F-type supergiant with a mean apparent magnitude of +3.81 and a spectral classification F8Ib. Estimates of its distance to Earth vary between 3,200 and 8,300 light-years.
S Persei is a red supergiant or hypergiant located near the Double Cluster in Perseus, north of the cluster NGC 869. It is a member of the Perseus OB1 association and one of the largest known stars. If placed in the Solar System, its photosphere would engulf the orbit of Jupiter. It is also a semiregular variable, a star whose variations are less regular than those of Mira variables.
6 Cassiopeiae is a white hypergiant in the constellation Cassiopeia, and a small-amplitude variable star.
A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term hypergiant is defined as luminosity class 0 (zero) in the MKK system. However, this is rarely seen in literature or in published spectral classifications, except for specific well-defined groups such as the yellow hypergiants, RSG (red supergiants), or blue B(e) supergiants with emission spectra. More commonly, hypergiants are classed as Ia-0 or Ia+, but red supergiants are rarely assigned these spectral classifications. Astronomers are interested in these stars because they relate to understanding stellar evolution, especially star formation, stability, and their expected demise as supernovae. A common example of a hypergiant is UY Scuti, although being a supergiant UY Scuti is considered a hypergiant by some people.
HD 168607 is a blue hypergiant and luminous blue variable (LBV) star located in the constellation of Sagittarius, easy to see with amateur telescopes. It forms a pair with HD 168625, also a blue hypergiant and possible luminous blue variable, that can be seen at the south-east of M17, the Omega Nebula.
Sigma Cygni, Latinised from σ Cygni, is a blue supergiant star in the constellation Cygnus. Its apparent magnitude is 4.2. It belongs to the Cygnus OB4 stellar association and is located approximately 3,300 light years away from Earth.
55 Cygni is a blue supergiant star in the constellation Cygnus. It is thought to be a member of the Cygnus OB7 stellar association at about 2,700 light years.
PZ Cassiopeiae is a red supergiant star located in the constellation of Cassiopeia, and a semi-regular variable star.
HD 160529 is a luminous blue variable (LBV) star located in the constellation of Scorpius. With an apparent magnitude of around +6.8 cannot be seen with the naked eye except under very favourable conditions, but it is easy to see with binoculars or amateur telescopes.
Sigma Ophiuchi, Latinized from σ Ophiuchi, is a single, orange-hued star in the equatorial constellation Ophiuchus. Its apparent visual magnitude is 4.31, which is bright enough to be faintly visible to the naked eye. The annual parallax shift of 3.62 mas as seen from Earth provides a distance estimate of roughly 900 light years. It is moving closer to the Sun with a radial velocity of −28 km/s.
HR 5171, also known as V766 Centauri, is a yellow hypergiant in the constellation Centaurus. It is said to be either an extreme red supergiant (RSG) or recent post-red supergiant (Post-RSG) yellow hypergiant (YHG), both of which suggest it is one of the largest known stars. The star's diameter is uncertain but likely to be between 1,100 and 1,600 times that of the Sun, while its distance is 3.6 kpc from Earth.
V915 Scorpii is a hypergiant and semiregular variable star, located 1,718 parsecs (5,600 ly) away in the constellation Scorpius. Its apparent magnitude varies between 6.22 and 6.64, being heavily diminshed by 2.93 magnitudes due to interstellar extinction.
HD 37836 is a candidate luminous blue variable located in the Large Magellanic Cloud and one of the brightest stars in its galaxy.