Omicron Cassiopeiae

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Template:Short description

ο Cassiopeiae
File:Omicron cassiopeiae diagram.jpg
Map of the Bayer-designated stars in Cassiopeia. Omicron Cassiopeiae is circled.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cassiopeia
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 4.30 - 4.62[2]
Characteristics
Spectral type B2-5III-Ve(shell)[2]
U−B Template:Engvar −0.53[3]
B−V Template:Engvar −0.06[3]
Variable type γ Cas[2]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[4] km/s
Proper motion (μ) RA: +18.84[5] mas/yr
Dec.: −7.18[5] mas/yr
Parallax (π)4.7046±0.4306 mas[5]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−2.55 / 0.35[4]
Orbit[4]
Primaryο Cas Aa
Companionο Cas Ab
Period (P)1031.55 d
Semi-major axis (a)0.0170 ± 0.0006″
Eccentricity (e)0
Inclination (i)115.0±2.6°
Longitude of the node (Ω)267.3±0.8°
Periastron epoch (T)JD 2452792.2±0.6
Argument of periastron (ω)
(secondary)		0°
Semi-amplitude (K1)
(primary)		21.593±0.071 km/s
Details[4]
ο Cas Aa
Mass6.2 Template:Solar mass
Radius8.0 Template:Solar radius
Temperature14,000 K
Rotational velocity (v sin i)220 km/s
ο Cas Ab
Mass~5 Template:Solar mass
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist
Database references
SIMBADο Cas A
ο Cas B

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Omicron Cassiopeiae (ο Cas, ο Cassiopeiae) is a triple star system in the constellation Cassiopeia. It is approximately 700 light-years from Earth, based on its parallax.[1] It is visible to the naked eye with a slightly variable apparent magnitude of about 4.5.

File:OmicronCasLightCurve.png
A visual band light curve for Omicron Cassiopeiae, adapted from Koubský et al. (2010)[4]

The primary component, ο Cassiopeiae A, is a spectroscopic binary, and its close companion completes one orbit every 2.83 years (1,031.55 days). The system has also been resolved with interferometry.[4]

The primary of this spectroscopic binary is a blue-white B-type giant star.[6] It is classified as a Gamma Cassiopeiae variable and its brightness varies from magnitude 4.30 to 4.62. It is rotating at a speed of 375 km/s at its equator (close to its theoretical break-up velocity of 390 km/s), although because the pole is inclined 36 degrees, its projected rotational velocity is only 220 km/s.[4] The nature of the secondary is not well known. Despite the fact that the secondary is 2.9 magnitudes dimmer than the primary, the secondary appears to have a mass similar to, or even larger than primary.[4] It is possible that the secondary is a pair of early A-type main-sequence stars.[4]

A more distant companion, ο Cassiopeiae B, lies 33.6 arcseconds away. It is an eleventh-magnitude, F-type main-sequence star.[6] Because it has a similar proper motion to the central system, it is assumed to be gravitationally bound.[7]

References

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  1. ↑ a b c Template:R:Van Leeuwen 2007 Validation of the new Hipparcos reduction
  2. ↑ a b c Script error: No such module "Citation/CS1".
  3. ↑ a b Script error: No such module "Citation/CS1".
  4. ↑ a b c d e f g h i Script error: No such module "Citation/CS1".
  5. ↑ a b c Template:Cite DR2
  6. ↑ a b Script error: No such module "Citation/CS1".
  7. ↑ Script error: No such module "Citation/CS1".

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Template:Stars of Cassiopeia

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