![]() ![]() "Comments on the variability and physical parameters of the F supergiant Phi Cassiopeiae". "Clusters and mirages: Cataloguing stellar aggregates in the Milky Way". ![]() " Gaia Data Release 2: Summary of the contents and survey properties". "Catalogue des composantes d'etoiles doubles et multiples (CCDM) premiere edition - Catalogue of the components of double and multiple stars (CCDM) first edition". The Complete Guide to the Herschel Objects: Sir William Herschel's Star Clusters, Nebulae and Galaxies. "Galactic B-supergiants: A non-LTE model atmosphere analysis to estimate atmospheric parameters and chemical compositions". "B-Type Variables in the Young Open Cluster Ngc 457". Monthly Notices of the Royal Astronomical Society. "Characteristics and classification of A-type supergiants in the Small Magellanic Cloud". "A determination of the basic atmospheric parameters of Phi Cassiopeiae". "Early-type stars in OB associations in the infrared. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations". ![]() "Astrophysical supplements to the ASCC-2.5: Ia. "Accurate luminosities from the oxygen 7771-4 a triplet and the fundamental parameters of F-G supergiants". Mean radial velocities for 1309 stars and 166 open clusters". CDS/ADC Collection of Electronic Catalogues. "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". "A catalogue of multiplicity among bright stellar systems". Gaia DR3 record for this source at VizieR. Summary of the content and survey properties". It is a suspected variable and a suspected spectroscopic binary. Ĭomponent C is a relatively typical B class supergiant, 83,000 times the luminosity of the sun. Different authors have published values from 6 M ☉ to 17 M ☉. More uncertain is the mass, which would be expected to have been well over 25 M ☉ initially, but much less now. Various model atmospheres all give a temperature around 7,300K, a low surface gravity, a radius around 250 R ☉, and a luminosity well over 100,000 L ☉. Its absolute magnitude is comparable to some yellow hypergiants but it does not show the level of mass loss and instability that would qualify it as a hypergiant itself. The primary component of the φ Cassiopeiae system is a very luminous yellow supergiant. Their Gaia Data Release 2 parallaxes are comparable to other stars in the cluster and consistent with the accepted distance of NGC 457, and component C has been given a 70% likelihood of being a member of the cluster. The two supergiants share a similar space motion to the other stars in NGC 457, but their evolutionary status and brightness makes them unlikely members. Another three components are sometimes listed as components of the multiple system, although this is somewhat arbitrary with dozens of members of NGC 457 being found within a few arc-minutes. Components D and E and both 10th magnitude B-type main sequence stars in NGC 457, with component E only 42" from φ 2. Component B is a 12th magnitude star 49" from φ 1. The two components A and C are the brightest members of NGC 457 they are sometimes referred to as φ 1 and φ 2 Cassiopeiae. φ Cas is generally treated as having five component stars, designated A to E in order of distance from the brightest star. Φ Cassiopeiae appears among the stars of the open cluster NGC 457, which is at 2,400pc, but it is uncertain whether it is a member of the cluster. Φ 1 and φ 2 Cassiopeiae are the two brightest star in the field of open cluster NGC 457.
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