Back رو ذات الكرسي Arabic Rho Cassiopeiae AST Rho Cassiopeiae BS Rho Cassiopeiae Catalan Ró Cassiopeiae Czech Rho Cassiopeiae German Rho Cassiopeiae Spanish رو ذات‌الکرسی Persian Rho Cassiopeiae Finnish Rho Cassiopeiae French

Rho Cassiopeiae

Rho Cassiopeiae

Rho Cas imaged with the CHARA Array in the H-band wavelengths.
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia
Right ascension 23h 54m 23.0s[1]
Declination +57° 29′ 58″[1]
Apparent magnitude (V) 4.1 to 6.2[2]
Characteristics
Spectral type G2Iae[3] (F8pIa-K0pIa-0)[2]
U−B color index 1.15[4]
B−V color index 1.26[4]
Variable type SRd[2]
Astrometry
Radial velocity (Rv)−47[3] km/s
Proper motion (μ) RA: −4.54[1] mas/yr
Dec.: −3.45[1] mas/yr
Parallax (π)0.9470 ± 0.2021 mas[5]
Distance8,150±1,630 ly
(2,500±500 pc)[6]
Absolute magnitude (MV)–9.5[7]
Details
Mass40[7] M☉
Radius564±67 – 700±112[8] R☉
Luminosity302,000 – 530,000,[6] 129,000[9] L☉
Surface gravity (log g)0.1[3] cgs
Temperature4,571 – 6,044[6] K
Metallicity [Fe/H]0.3[10] dex
Rotational velocity (v sin i)25[11] km/s
Age4 – 6[7] Myr
Other designations
7 Cassiopeiae, HR 9045, BD+56°3111, HD 224014, SAO 35879, FK5 899, HIP 117863, GC 33160
Database references
SIMBADdata

Rho Cassiopeiae (/ˌroʊ kæsiəˈpiːaɪ, -sioʊ-, -iː/; ρ Cas, ρ Cassiopeiae) is a yellow hypergiant star in the constellation Cassiopeia. It is about 8,150 light-years (2,500 pc) from Earth, yet can still be seen by the naked eye as it is over 300,000 times brighter than the Sun. On average it has an absolute magnitude of −9.5, making it visually one of the most luminous stars known. Recently imaged and measured by the CHARA array in 2024, its diameter measures between 564 and 700 times that of the Sun, approximately 879,000,000 kilometers (5.88 AU; 546,000,000 mi), or 2.6 to 3.3 times the size of Earth's orbit.[12]

Louisa Wells discovered that the star's brightness varies, and that discovery was published in 1901.[13] Rho Cassiopeiae is a single star, and is categorized as a semiregular variable. As a yellow hypergiant, it is one of the rarest types of stars. Only a few dozen are known in the Milky Way, but it is not the only one in its constellation which also contains V509 Cassiopeiae.[14]

  1. ^ a b c d Cite error: The named reference hipparcos was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference GCVS-Rho-Cas was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference klotchkova was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference ducati was invoked but never defined (see the help page).
  5. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  6. ^ a b c Cite error: The named reference van was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference gorlova was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference anugu was invoked but never defined (see the help page).
  9. ^ Klochkova, V. G. (2019). "Unity and Diversity of Yellow Hypergiants Family". Astrophysical Bulletin. 74 (4): 475–489. arXiv:1911.09387. Bibcode:2019AstBu..74..475K. doi:10.1134/S1990341319040138. S2CID 208202411.
  10. ^ Cite error: The named reference israelian was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference lobel was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference aungu was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Pickering1901 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference border was invoked but never defined (see the help page).
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