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QZ Carinae (HD 93206) is a multiple star system in the constellation Carina. It is the brightest member of the loose open cluster Collinder 228 and one of the brightest stars in the Carina Nebula. The apparent magnitude is variable from +6.16 to +6.49 with a period of 6 days.
QZ Carinae is approximately 2,300 parsecs (7,500 light-years) from Earth in the Carina Nebula star-forming region.
QZ Carinae is a complex multiple star system made up of at least nine individual stars. [8] Four massive luminous stars dominate the light output of the system. [9] They form a quadruple system of two spectroscopic binaries: Aa (designated A1 and A2) and eclipsing binary Ac (designated B1 and B2).
The A1/A2 and B1/B2 pairs take no more than 25 years to orbit each other, while the A pair completes an orbit around each other every 20.7 days and the B pair every 6.0 days. The system is bright at x-ray wavelengths primarily due to colliding stellar winds in the two close pairs. Pair A1/A2 contributes the bulk of the x-ray luminosity. [4]
QZ Carinae A1 is a blue supergiant of spectral type O9.7I with around 40 times the Sun's mass that has expanded to 22.5 times the Sun's radius. With a surface temperature of 32,000 K, it is around 500,000 times as luminous as the Sun. Its partner A2 is a blue-white main sequence star of spectral type B2V with around 10 times the Sun's mass and 6 times its radius. With a surface temperature of 20,000 K, it is around 5,000 times as luminous as the Sun.
QZ Carinae B1 is a hot blue giant that is expanding and cooling away from the main sequence. It is of spectral type O8III with around 14.1 times the Sun's mass and 26.9 times its radius. With a surface temperature of 32,573 K, it is around 200,000 times as luminous as the Sun. Partner B2 is a hot main sequence star of spectral type O9V with around 28 times the Sun's mass and 8.9 times its radius. With a surface temperature of 32,463 K, it is around 80,000 times as luminous as the Sun. Star B1 is less massive than B2 and is assumed to have undergone significant mass loss or mass transfer to B2. [4] Together, all four stars have a combined mass 94 times that of the Sun. [10]
Star B is a Beta Lyrae variable eclipsing system. It causes the apparent magnitude of the system to vary regularly every 5.999 days from +6.16 at maximum to +6.49 at the primary minimum and +6.43 at the secondary minimum. [3] It was first noted to be variable in 1972 by observers in Auckland. [10]
Epsilon Carinae, officially named Avior, is a binary star in the southern constellation of Carina. At apparent magnitude +1.86 it is one of the brightest stars in the night sky, but is not visible from most of the northern hemisphere. The False Cross is an asterism formed of Delta Velorum, Kappa Velorum, Iota Carinae and ε Carinae. It is so called because it is sometimes mistaken for the Southern Cross, causing errors in astronavigation.
p Carinae is the Bayer designation of a star in the southern constellation of Carina. It has the variable star designation PP Carinae and, at an apparent visual magnitude of +3.3, is readily visible to the naked eye from the southern hemisphere. From the observed parallax shift of this star as the Earth orbits the Sun, its distance can be estimated as roughly 480 light-years with a 6% margin of error. It is considered to be a member of the open cluster IC 2602 although it lies well outside the core visible group of stars.
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.
V520 Carinae is a single star in the southern constellation of Carina. It has the Bayer designation w Carinae, while V520 Carinae is a variable star designation. The star has an orange hue and is faintly visible to the naked eye with an apparent visual magnitude that fluctuates around +4.58. It is located at a distance of approximately 1,140 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +9 km/s. It is a candidate member of the IC 2391 moving group of co-moving stars.
V345 Carinae is a star in the constellation Carina. It has the Bayer designation E Carinae; V345 Carinae is the variable star designation. The star has a blue-white hue and is faintly visible to the naked eye with an apparent visual magnitude that fluctuates around +4.66. Its actual brightness varies from magnitude +4.67 to +4.78 with a period of 137.7 days. Based on parallax measurements, it is located at a distance of approximately 1,010 light years from the Sun. It is drifting further away with a radial velocity of around +19 km/s.
HD 92063 is a single star in the southern constellation of Carina. It has the Bayer designation t1 Carinae, while HD 92063 is the star's identifier from the Henry Draper Catalogue. This is a suspected variable star and is visible to the naked eye with an apparent visual magnitude of 5.08. The star is located at a distance of approximately 246 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −10 km/s. Although it appears at the edge of the Carina Nebula, it is much closer than the nebula. It is also not considered a member of the nearby Alessi 5 open cluster of stars.
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.
Y Carinae is a Classical Cepheid variable, a type of variable star, in the constellation Carina. Its apparent magnitude varies from 7.53 to 8.48.
AG Carinae is a star in the constellation Carina. It is classified as a luminous blue variable (LBV) and is one of the most luminous stars in the Milky Way. The great distance and intervening dust mean that the star is not usually visible to the naked eye; its apparent brightness varies erratically between magnitude 5.7 and 9.0.
HR Carinae is a luminous blue variable star located in the constellation Carina. It is surrounded by a vast nebula of ejected nuclear-processed material because this star has a multiple shell expanding atmosphere. This star is among the most luminous stars in the Milky Way. It has very broad emission wings on the Balmer lines, reminiscent from the broad lines observed in the spectra of O and Wolf–Rayet stars. A distance of 5 kpc and a bolometric magnitude of −9.4 put HR Car among the most luminous stars of the galaxy.
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. Notable examples of hypergiants include the Pistol Star, a blue hypergiant located close to the Galactic Center and one of the most luminous stars known; Rho Cassiopeiae, a yellow hypergiant that is one of the brightest to the naked eye; and Mu Cephei (Herschel's "Garnet Star"), one of the largest and brightest stars known.
V518 Carinae is a naked-eye variable star in the constellation Carina. It is a member of the bright open cluster IC 2602 near the Carina Nebula.
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.
Trumpler 16 is a massive open cluster that is home to some of the most luminous stars in the Milky Way galaxy. It is situated within the Carina Nebula complex in the Carina–Sagittarius Arm, located approximately 9,270 ly (2,842 pc) from Earth. The cluster has one star visible to the naked eye from the tropics southward, Eta Carinae.
HD 93403 is a spectroscopic binary containing two highly luminous hot blue stars. It is 10,000 light years away in the Carina Nebula in the constellation Carina. It appears to have spectral type O5.5III, but this is composed of two spectra from a blue supergiant and blue main sequence star of spectral type O5.5I and O7V respectively. The two stars orbit every 15 days with a separation that varies from 93 R☉ to 149 R☉. The binary is shedding mass at the high rate of 0.0005 M☉ per year.
CK Carinae is a variable star in the constellation Carina, the keel of Argo Navis. It is a member of the star association Carina OB1-D, at a distance of around 2,300 parsecs or 7,500 light years.
V528 Carinae is a variable star in the constellation Carina.
Collinder 228 is an open cluster within the southern part of the Carina Nebula NGC 3372, about 25' south of η Carinae. It is probably composed of stars which recently formed from the material in the nebula. QZ Carinae is the brightest member of Collinder 228 with an apparent magnitude between 6.16–6.49 .