MY Cephei

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MY Cephei
NGC 7419 2MASS.jpg
MY Cephei is the brightest star in this infrared image of NGC 7419.
Credit: 2MASS
Observation data
Epoch J2000.0        Equinox J2000.0
Constellation Cepheus
Right ascension 22h 54m 31.698s [1]
Declination +60° 49′ 38.97″ [1]
Apparent magnitude  (V)14.4–15.5 [2]
Characteristics
Evolutionary stage Extreme [3] OH/IR red supergiant [4]
Spectral type M3, [5] M7–7.5 I [6] (M6–7Iab [2] )
Apparent magnitude  (G)10.225 [1]
Apparent magnitude  (H)2.98 [7]
Apparent magnitude  (K)2.14 [7]
Variable type SRc [2]
Astrometry
Proper motion (μ)RA: –2.637 [1]   mas/yr
Dec.: –1.883 [1]   mas/yr
Parallax (π)0.3398 ± 0.0708  mas [1]
Distance 3,000+350
−290 [8]   pc
Details
Mass 14.5 [9]   M☉
Radius 1,028 ± 169 –1,138 ± 387 [5] [lower-alpha 1]   R☉
Luminosity 159,000+60,000
−44,000 –195,000+173,000
−92,000 [5] [lower-alpha 2]   L☉
Temperature 3,595±31 [5]   K
Age 9 [6]   Myr
Other designations
MY  Cep, IRC  +60375, 2MASS  J22543171+6049388, IRAS  22525+6033, RAFGL  2987
Database references
SIMBAD data

MY Cephei (IRC +60375) 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.

Contents

Observations and variability

A visual band light curve for MY Cephei, plotted from ASAS-SN data MYCepLightCurve.png
A visual band light curve for MY Cephei, plotted from ASAS-SN data

Observations of the open cluster NGC 7419 in 1954 showed that four of its members were luminous red stars, most likely red supergiants. In addition, an unusually red star was found to be variable and probably an even more luminous supergiant. [11] This star was given the variable star designation MY Cephei in 1973 in the 59th name-list of variable stars. [12]

MY Cephei is classified as semiregular variable star of sub-type SRc, indicating it is a cool supergiant, although its pulsational period is not known. It has been observed as bright as magnitude 14.4 and as faint as magnitude 15.5. [2] The star, along with another late red supergiant star, S Persei, are sometimes considered prototypes for the class of M6–7 supergiants. [13]

Distance

The distance of MY Cephei is assumed to be around 9,780+1,140
−950  light years or 3,000+350
−290  parsecs based on it being a member of the NGC 7419 open cluster. [6] [8] Gaia Early Data Release 3 gives a parallax of 0.3398±0.0708  mas for MY Cep, [1] implying a similar distance of 2,691+511
−419  pc . [14]

Stellar properties

The spectral type of MY Cephei is given in the General Catalogue of Variable Stars as M6–7 Iab, indicating the star is an intermediate-size luminous supergiant star, [2] although most authors gives M7–M7.5 I. [6] Classification is difficult because of the lack of comparable standard stars, but its spectrum appears to be later than M5, earlier than VX Sagittarii when at M9, and more luminous than M7 giant stars. [13] A 2021 study gives a spectral class of M3 based on infrared observations, and a correspondingly higher temperature. [5]

MY Cephei is a very luminous, cool and large extreme supergiant star, with a luminosity more than 100,000 times that of the Sun (L☉) and a radius in excess of a thousand times the Sun's radius (R☉). It is likely the most luminous, coolest, and the largest supergiant star in its open cluster, [6] and occupies the upper-right hand corner of the Hertzsprung–Russell diagram.

A 2018 paper gives the star a temperature of 3,400  K , corresponding a radius of 1,134 R☉ based on a luminosity of 155,000 L☉. [15] The mass of MY Cephei is uncertain, but expected to be around 14.5 times the Sun's mass (M☉). [9] Mass is being lost at (2.3±0.3)×10−5 M☉ per year, one of highest mass loss rates known for a supergiant star. [6]

A study from 2020 based on SED integration gives an unexpectedly higher bolometric luminosity of 310,000±70,000 L☉, close to the empirical upper luminosity limit of red supergiants (i.e. Humphreys–Davidson limit). This implies a higher radius of 2,061 ± 233 R☉ based on an effective temperature of 3,000 K derived using the DUSTY model, considerably larger than the upper radius limit of red supergiants at roughly 1,500 R☉ respectively. [16] [6] Older studies frequently calculated even more lower temperatures and an estimated radius of 2,400 R☉. [13]

See also

Notes

  1. ↑ Applying the Stefan-Boltzmann Law with a nominal solar effective temperature of 5,772  K:
    .
  2. ↑ Calculated using the following equation:

    , where mbol is the star's apparent bolometric magnitude and d is the distance in parsecs. The values used for the mbol are 4.29±0.35 and 4.07±0.69, while the value used for the distance is 3,240 parsecs.

Related Research Articles

<span class="mw-page-title-main">Supergiant</span> Type of star that is massive and luminous

Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spans from about 3,400 K to over 20,000 K.

<span class="mw-page-title-main">Red supergiant</span> Stars with a supergiant luminosity class with a spectral type of K or M

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.

<span class="mw-page-title-main">Mu Cephei</span> Red supergiant star in the constellation Cepheus

Mu Cephei, also known as Herschel's Garnet Star, Erakis, or HD 206936, is a red supergiant or hypergiant star in the constellation Cepheus. It appears garnet red and is located at the edge of the IC 1396 nebula. Since 1943, the spectrum of this star has served as a spectral standard by which other stars are classified.

<span class="mw-page-title-main">VV Cephei</span> Binary star in the constellation Cepheus

VV Cephei, also known as HD 208816, is an eclipsing binary star system located in the constellation Cepheus. It is both a B[e] star and shell star.

<span class="mw-page-title-main">KY Cygni</span> Star in the constellation Cygnus

KY Cygni is a red supergiant of spectral class M3.5Ia located in the constellation Cygnus. It is approximately 4,700 light-years away.

<span class="mw-page-title-main">Phi Cassiopeiae</span> Star in the constellation Cassiopeia

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".

KW Sagittarii is a red supergiant star, located approximately 2,420 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.

V354 Cephei is a red supergiant star located within the Milky Way. It is an irregular variable located over 13,000 light-years away from the Sun. It has an estimated radius of 1,139 solar radii. If it were placed in the center of the Solar System, it would extend to between the orbits of Mars and Jupiter.

<span class="mw-page-title-main">HD 74180</span> Supergiant star in the constellation Vela

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.

<span class="mw-page-title-main">S Persei</span> Red supergiant or hypergiant variable star in the constellation Perseus

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.

<span class="mw-page-title-main">RW Cephei</span> Hypergiant star in the constellation Cepheus

RW Cephei is a K-type hypergiant and a semirregular variable star in the constellation Cepheus, at the edge of the Sharpless 132 H II region and close to the small open cluster Berkeley 94. It is among the largest stars known with a radius of 1,100 times that of the Sun (R☉), nearly as large as the orbit of Jupiter.

<span class="mw-page-title-main">WOH G64</span> Red supergiant in the constellation Dorado

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 the largest known star with a well-defined radius. 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☉).

<span class="mw-page-title-main">VY Canis Majoris</span> Star in the constellation Canis Major

VY Canis Majoris is an extreme oxygen-rich red hypergiant or red supergiant and pulsating variable star 1.2 kiloparsecs from the Solar System in the slightly southern constellation of Canis Major. It is one of the largest known stars, one of the most luminous and massive red supergiants, and one of the most luminous stars in the Milky Way.

<span class="mw-page-title-main">NML Cygni</span> Star in the constellation Cygnus

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.

<span class="mw-page-title-main">UY Scuti</span> Star in the constellation Scutum

UY Scuti (BD-12°5055) is a red supergiant star, located 5,900 light-years away in the constellation Scutum. It is also a pulsating variable star, with a maximum brightness of magnitude 8.29 and a minimum of magnitude 10.56, which is too dim for naked-eye visibility. It is considered to be one of the largest known stars, with a radius estimated at 909 solar radii, thus a volume of 750 million times that of the Sun. This estimate implies if it were placed at the center of the Solar System, its photosphere would extend past the orbit of Mars or even the asteroid belt.

<span class="mw-page-title-main">RS Persei</span> Star in the constellation Perseus

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.

<span class="mw-page-title-main">EV Carinae</span> Red supergiant star in the constellation Carina

EV Carinae is a red supergiant and pulsating variable star of spectral type M4Ia in the constellation Carina. It is a semiregular variable star with its apparent magnitude varying between 7.4 and 9.0 in the visible band, making it only seen by binoculars or a telescope. Various periods have been identified, but the dominant one is around 347 days. It is an MK spectral standard star for the class M4.5Ia.

<span class="mw-page-title-main">NGC 7419</span> Open cluster in the constellation Cepheus

NGC 7419 is an open cluster in the constellation Cepheus. It is heavily reddened and notable for containing five red supergiants, the highest number known in any cluster until the end of the 20th century, but probably no blue supergiants.

<span class="mw-page-title-main">Stephenson 2 DFK 1</span> Star in the open cluster Stephenson 2

Stephenson 2 DFK 1, also known as RSGC2-01 or St2-18, is a red supergiant (RSG) or possible extreme red hypergiant (RHG) star in the constellation of Scutum. It lies near the open cluster Stephenson 2, which is located about 5.8 kiloparsecs away from Earth in the Scutum–Centaurus Arm of the Milky Way galaxy, and is assumed to be one of a group of stars at a similar distance, although some studies consider it to be an unrelated or foreground red supergiant.

<span class="mw-page-title-main">Westerlund 1-75</span> Red supergiant in the Westerlund 1 super star cluster

Westerlund 1 W75 or Wd 1-75 is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius is calculated to be around 668 solar radii (4.65 × 108 km, 3.10 au). This corresponds to a volume 298 million times bigger than the Sun. If placed at the center of the Solar System, Westerlund 1-75 would engulf the inner limits of the asteroid belt.

References

  1. 1 2 3 4 5 6 7 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. 1 2 3 4 5 "GCVS Query=MY Cep". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia . Retrieved 2020-08-06.
  3. ↑ Davies, Ben; Beasor, Emma R. (2019). "The distances to star clusters hosting Red Supergiants: χ per, NGC 7419, and Westerlund 1". Monthly Notices of the Royal Astronomical Society: Letters. 486: L10–L14. arXiv: 1903.12506 . doi: 10.1093/mnrasl/slz050 . S2CID   88517447.
  4. ↑ Beauchamp, Alain; Moffat, Anthony F. J.; Drissen, Laurent (1994). "The galactic open cluster NGC 7419 and its five red supergiants". Astrophysical Journal Supplement Series. 93: 187. Bibcode:1994ApJS...93..187B. doi:10.1086/192051.
  5. 1 2 3 4 5 Messineo, Maria; Figer, Donald F.; Kudritzki, Rolf-Peter; Zhu, Qingfeng; Menten, Karl M.; Ivanov, Valentin D.; Chen, C. -H. Rosie (2021). "New Infrared Spectral Indices of Luminous Cold Stars: From Early K to M Types". The Astronomical Journal. 162 (5): 187. arXiv: 2107.03707 . Bibcode:2021AJ....162..187M. doi: 10.3847/1538-3881/ac116b . S2CID   235765247.
  6. 1 2 3 4 5 6 7 Humphreys, Roberta M.; Helmel, Greta; Jones, Terry J.; Gordon, Michael S. (August 2020). "Exploring the Mass Loss Histories of the Red Supergiants". The Astronomical Journal. 160 (3): 145. arXiv: 2008.01108 . Bibcode:2020AJ....160..145H. doi: 10.3847/1538-3881/abab15 . S2CID   220961677.
  7. 1 2 Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  8. 1 2 Davies, Ben; Beasor, Emma R. (March 2020). "The 'red supergiant problem': the upper luminosity boundary of Type II supernova progenitors". MNRAS . 493 (1): 468–476. arXiv: 2001.06020 . Bibcode:2020MNRAS.493..468D. doi: 10.1093/mnras/staa174 . S2CID   210714093.
  9. 1 2 Marco, A.; Negueruela, I. (2013). "NGC 7419 as a template for red supergiant clusters". Astronomy & Astrophysics. 552: A92. arXiv: 1302.5649 . Bibcode:2013A&A...552A..92M. doi:10.1051/0004-6361/201220750. S2CID   53723223.
  10. ↑ "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 3 December 2022.
  11. ↑ Blanco, V.; Nassau, J. J.; Stock, J.; Wehlau, W. (1955). "M-Type Stars in NGC 7419". The Astrophysical Journal. 121: 637. Bibcode:1955ApJ...121..637B. doi:10.1086/146029.
  12. ↑ Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (1973). "59th Name-List of Variable Stars". Information Bulletin on Variable Stars. 834: 1. Bibcode:1973IBVS..834....1K.
  13. 1 2 3 Fawley, W. M.; Cohen, M. (1974). "The open cluster NGC 7419 and its M7 supergiant IRC +60 375". Astrophysical Journal. 193: 367. Bibcode:1974ApJ...193..367F. doi: 10.1086/153171 .
  14. ↑ Bailer-Jones, C. A. L.; Rybizki, J.; Fouesneau, M.; Demleitner, M.; Andrae, R. (2021). "Estimating Distances from Parallaxes. V. Geometric and Photogeometric Distances to 1.47 Billion Stars in Gaia Early Data Release 3". The Astronomical Journal. 161 (3): 147. arXiv: 2012.05220 . Bibcode:2021AJ....161..147B. doi: 10.3847/1538-3881/abd806 . S2CID   228063812.
  15. ↑ Beasor, Emma R; Davies, Ben; Arroyo-Torres, B; Chiavassa, A; Guirado, J. C; Marcaide, J. M; Alberdi, A; De Wit, W. J; Hofmann, K. -H; Meilland, A; Millour, F; Mohamed, S; Sanchez-Bermudez, J (2018). "The evolution of red supergiant mass-loss rates". Monthly Notices of the Royal Astronomical Society. 475 (1): 55. arXiv: 1712.01852 . Bibcode:2018MNRAS.475...55B. doi: 10.1093/mnras/stx3174 . S2CID   55822928.
  16. ↑ Emily M. Levesque; Philip Massey; K. A. G. Olsen; Bertrand Plez; et al. (August 2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought". The Astrophysical Journal . 628 (2): 973–985. arXiv: astro-ph/0504337 . Bibcode:2005ApJ...628..973L. doi:10.1086/430901. S2CID   15109583.
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