Cepheus (constellation)

Cepheus
Constellation
Cepheus
AbbreviationCep
GenitiveCephei
Pronunciation/ˈsfiəs/ or /ˈsfjuːs/;
genitive /ˈsfi/
Symbolismthe King/King Cepheus
Right ascension20h 01m 56.4481s09h 03m 19.7931s[1]
Declination88.6638870°–53.3532715°[1]
Area588 sq. deg. (27th)
Main stars7
Bayer/Flamsteed
stars
43
Stars with planets1
Stars brighter than 3.00m1
Stars within 10.00 pc (32.62 ly)3
Brightest starα Cep (Alderamin) (2.45m)
Messier objects0
Meteor showers0
Bordering
constellations
Cygnus
Lacerta
Cassiopeia
Camelopardalis
Draco
Ursa Minor
Visible at latitudes between +90° and −10°.
Best visible at 21:00 (9 p.m.) during the month of November.

Cepheus is a constellation in the deep northern sky, named after Cepheus, a king of Aethiopia in Greek mythology. It is one of the 48 constellations listed by the second century astronomer Ptolemy, and it remains one of the 88 constellations in the modern times.

The constellation's brightest star is Alpha Cephei, with an apparent magnitude of 2.5. Delta Cephei is the prototype of an important class of star known as a Cepheid variable. RW Cephei, an orange hypergiant, together with the red supergiants Mu Cephei, MY Cephei, VV Cephei, V381 Cephei, and V354 Cephei are among the largest stars known. In addition, Cepheus also has the hyperluminous quasar S5 0014+81, which hosts an ultramassive black hole in its core, reported at 40 billion solar masses, about 10,000 times more massive than the central black hole of the Milky Way, making this among the most massive black holes currently known.[2][3]

  1. ^ a b "Cepheus, constellation boundary". The Constellations. International Astronomical Union. Retrieved 15 February 2014.
  2. ^ Ghisellini, G.; Ceca, R. Della; Volonteri, M.; Ghirlanda, G.; Tavecchi, F.; Foschini, L.; Tagliaferri, G.; Haardt, F.; Pareschi, G.; Grindlay, J. (2010). "Chasing the heaviest black holes in active galactic nuclei, the largest black hole". Monthly Notices of the Royal Astronomical Society. 405 (1): 387. arXiv:0912.0001. Bibcode:2010MNRAS.405..387G. doi:10.1111/j.1365-2966.2010.16449.x. S2CID 40214759. This paper does acknowledge the possibility of an optical illusion that would cause an overestimation of the mass.
  3. ^ Ghisellini, G.; Foschini, L.; Volonteri, M.; Ghirlanda, G.; Haardt, F.; Burlon, D.; Tavecchio, F.; et al. (14 July 2009). "The blazar S5 0014+813: a real or apparent monster?". Monthly Notices of the Royal Astronomical Society: Letters. v2. 399 (1): L24–L28. arXiv:0906.0575. Bibcode:2009MNRAS.399L..24G. doi:10.1111/j.1745-3933.2009.00716.x. S2CID 14438667.