Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cygnus |
Right ascension | 20h 02m 27.376s [2] |
Declination | +30° 04′ 25.49″ [2] |
Apparent magnitude (V) | 8.6-9.6 [1] |
Characteristics | |
Evolutionary stage | Yellow supergiant |
Spectral type | G7Ia [3] |
U−B color index | +1.9 –+2.8 [1] |
B−V color index | +2.1 –+2.5 [1] |
Variable type | L [4] |
Astrometry | |
Proper motion (μ) | RA: −2.936 [2] mas/yr Dec.: −5.55 [2] mas/yr |
Parallax (π) | 0.2390 ± 0.0178 mas [2] |
Distance | 14,000 ± 1,000 ly (4,200 ± 300 pc) |
Absolute magnitude (MV) | −7.956 [3] |
Details | |
Radius | 559 [3] [lower-alpha 1] R☉ |
Luminosity | 176,200 [3] L☉ |
Surface gravity (log g) | −0.81 [5] cgs |
Temperature | 5,000 [3] K |
Other designations | |
Database references | |
SIMBAD | data |
V1027 Cygni is a luminous yellow supergiant star located in the constellation of Cygnus, about 14,000 light years away. For a time, it was thought that it could be a low-mass post-AGB star, however recent parallax measurements published in Gaia DR3 have shown this to likely not be the case, and instead it is likely a massive yellow supergiant star. [3]
V1027 Cygni has a surface temperature about 5,000 K, which has been found in many studies. However, studies before Gaia DR3 generally used a distance around 1,280 pc , which led to low luminosity estimates, hence a tentative post-AGB star status. [1] Recent Gaia DR3 data shows that V1027 Cygni is likely much further away, over 4,000 pc away, which implies a much higher luminosity (about 176,000 L☉) which would place it firmly outside the post-AGB star luminosity range and in that of the more massive, younger yellow supergiants. [3] Spectral indicators of luminosity also suggest a supergiant status. [1]
Assuming a temperature of 5,000 K and a luminosity of about 176,200 L☉ for V1027 Cygni leads to a size of about 560 times that of the Sun. [lower-alpha 1]
When V1027 Cygni was first noticed as a variable star, it was thought to be an irregular variable, dimming and brightening erratically with no discernible period. However, in 2009, a small-amplitude period of 237 days was observed in long-term photometry of the star. [1]
Red supergiants (RSGs) are stars with a supergiant luminosity class and a stellar classification K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Antares A are the brightest and best known red supergiants (RSGs), indeed the only first magnitude red supergiant stars.
RV Tauri is a star in the constellation Taurus. It is a yellow supergiant and is the prototype of a class of pulsating variables known as RV Tauri variables. It is a post-AGB star and a spectroscopic binary about 4,700 light years away.
Gamma Trianguli Australis, Latinized from γ Trianguli Australis, is a single, white-hued star in the southern constellation of Triangulum Australe. Along with Alpha and Beta Trianguli Australis it forms a prominent triangular asterism that gives the constellation its name. It is the third-brightest member of this constellation with an apparent visual magnitude of +2.87. Based upon parallax measurements, Gamma Trianguli Australis is located at a distance of about 190 light-years from Earth.
KY Cygni is a red supergiant of spectral class M3.5Ia located in the constellation Cygnus. It is approximately 4,700 light-years away.
Phi Cassiopeiae is a multiple star in the constellation Cassiopeia with a combined apparent magnitude of +4.95. The two brightest components are A and C, sometimes called φ1 and φ2 Cas. φ Cas A is an F0 bright supergiant of magnitude 4.95 and φ Cas C is a 7.08 magnitude B6 supergiant at 134".
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.
KW Sagittarii is a red supergiant star, located approximately 2,160 parsecs away from the Sun in the direction of the constellation Sagittarius. It is one of the largest known stars, with a diameter about 1,000 times larger than the Sun. If placed at the center of the Solar System, the star's surface would engulf Mars, coming close to Jupiter's orbit.
MY Cephei is a red supergiant located in open cluster NGC 7419 in the constellation of Cepheus. It is a semiregular variable star with a maximum brightness of magnitude 14.4 and a minimum of magnitude 15.5.
WOH G64 is an unusual red supergiant (RSG) star in the Large Magellanic Cloud (LMC) satellite galaxy in the southern constellation of Dorado. It is one of the largest known stars, being described as possibly being the largest star known. It is also one of the most luminous and massive red supergiants, with a radius calculated to be around 1,540 times that of the Sun (R☉) and a luminosity around 282,000 times the solar luminosity (L☉).
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.
NML Cygni or V1489 Cygni is a red hypergiant or red supergiant (RSG) in the constellation Cygnus. It is possibly one of the largest known stars currently known, and is also possibly one of the most luminous and massive cool hypergiants, as well as one of the most luminous stars in the Milky Way.
HD 179821 or V1427 Aquilae is either a post-red supergiant yellow hypergiant or a post-AGB yellow supergiant star in the constellation of Aquila, surrounded by a detached dust shell. It is a semi-regular variable nearing the end of its life.
IRAS 19475+3119 is a protoplanetary nebula in the constellation of Cygnus, 15,000 light-years away. The central star, V2513 Cygni, is an F-type post-AGB star.
HV 2112 is a cool luminous variable star in the Small Magellanic Cloud. Until 2018, it was considered to be the most likely candidate for a Thorne–Żytkow object, but it is now thought to be an asymptotic giant branch star.
RS Persei is a red supergiant variable star located in the Double Cluster in Perseus. The star's apparent magnitude varies from 7.82 to 10.0, meaning it is never visible to the naked eye.
Y Lyncis is a semiregular variable star in the constellation Lynx. It is an asymptotic giant branch star of spectral type M6S, with a luminosity class of Ib, indicating a supergiant luminosity. It is around 1,160 light years away.
BC Cygni is a red supergiant and pulsating variable star of spectral type M3.5Ia in the constellation Cygnus.
RW Cygni is a semiregular variable star in the constellation Cygnus, about a degree east of 2nd magnitude γ Cygni. Its apparent magnitude varies between 8.05 and 9.70 and its spectral type between M3 and M4.
V1936 Aquilae is a blue supergiant and candidate Luminous blue variable located in the nebula Westerhout 51, in the constellation Aquila, about 20,000 light years away. The star was originally identified as a massive star in 2000, and was thought to be an O-type supergiant. However, subsequent analyses have shown it to be not O but B-type, as well as being possibly an LBV.
HD 37836 is a candidate luminous blue variable located in the Large Magellanic Cloud and one of the brightest stars in its galaxy.