Iota Cassiopeiae

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ι Cassiopeiae
Iota cassiopeiae diagram.jpg
The Bayer-designated stars in Cassiopeia. Iota Cassiopeiae is circled.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cassiopeia
ι Cas A
Right ascension 02h 29m 03.960s[1]
Declination +67° 24′ 08.70″[1]
Apparent magnitude (V) 4.61[1](4.65 / 8.48)[2]
ι Cas B
Right ascension 02h 29m 03.567s[1]
Declination +67° 24′ 07.01″[1]
Apparent magnitude (V) 6.87[1]
ι Cas C
Right ascension 02h 29m 05.086s[1]
Declination +67° 24′ 05.53″[1]
Apparent magnitude (V) 9.05[3](9.14 / 11.84)[3]
Characteristics
U−B color index +0.03[4]
B−V color index +0.12[4]
ι Cas A
Spectral type A3p / G6[2]
Variable type α2 CVn[5]
ι Cas B
Spectral type F5[2]
ι Cas C
Spectral type K4 / M2[3]
U−B color index +0.18[4]
B−V color index +0.72[4]
Astrometry
Radial velocity (Rv)1.2 ± 2[6] km/s
Proper motion (μ) RA: -26.61[7] mas/yr
Dec.: 38.21[7] mas/yr
Parallax (π)22.22 ± 0.08[8] mas
Distance146.8 ± 0.5 ly
(45.0 ± 0.2 pc)
Absolute magnitude (MV)1.62 ± 0.07 (Aa)
5.60 ± 0.17 (Ab)[9]
Orbit[8]
Primaryι Cas Aa
Companionι Cas Ab
Period (P)48.72 ± 0.45 yr
Semi-major axis (a)0.423 ± 0.004″
Eccentricity (e)0.637 ± 0.004
Inclination (i)148.2 ± 1.3°
Longitude of the node (Ω)176.6 ± 1.8°
Periastron epoch (T)B 1993.21 ± 0.05
Argument of periastron (ω)
(secondary)		328.2 ± 1.9°
Orbit[8]
Primaryι Cas A
Companionι Cas B
Period (P)2400 yr
Semi-major axis (a)6.50″
Eccentricity (e)0.40
Inclination (i)102.9 ± 0.3°
Longitude of the node (Ω)188.0 ± 0.9°
Periastron epoch (T)B 940 ± 47
Argument of periastron (ω)
(secondary)		113.3 ± 3.4°
Details
ι Cas Aa
Mass1.98[8] M☉
Radius2.3 ± 0.4[10] R☉
Luminosity24[10] L☉
Temperature8360 ± 275[10] K
Rotation1.74033 d[10]
Rotational velocity (v sin i)48[10] km/s
Age100[9] Myr
ι Cas Ab
Mass0.98[8] M☉
ι Cas B
Mass1.28[8] M☉
Temperature6540[3] K
ι Cas Ca
Temperature4520 ± 20[3] K
ι Cas Cb
Temperature3590 ± 45[3] K
Other designations
BD+66° 213, HD 15089, HIP 11569, HR 707, SAO 12298
ι Cas A: TYC 4058-1504-1
ι Cas B: TYC 4058-1504-2
ι Cas C: TYC 4058-1505-1
Database references
SIMBADι Cas
ι Cas AB
ι Cas A
ι Cas B
ι Cas C

Iota Cassiopeiae (ι Cas, ι Cassiopeiae) is a star system in the constellation Cassiopeia. The system has a combined apparent magnitude of 4.53,[11] making it visible to the naked eye. Based on its parallax, it is located about 133 light-years (41 parsecs) from Earth.[7]

Components[]

Iota Cassiopeiae is known to be a quintuple star system. The brightest star system, ι Cassiopeiae A, contains a white-colored A-type main-sequence star with a mean apparent magnitude of +4.61.[1] The primary component is a tighter binary star system itself. The two stars themselves were resolved by adaptive optics, revealing two stars. These are designated Aa and Ab (although confusingly they may also be labeled as A and Aa, respectively). The primary is classified as an Alpha2 Canum Venaticorum-type variable star and the brightness of the system varies from magnitude +4.45 to +4.53 with a period of 1.74 days,[5] because of its magnetic field.[10] The fainter companion is a G-type star with a mass of 0.98 M☉.[8] The orbital period of the system is about 49 years.[8]

A second component, ι Cassiopeiae B, is a yellow-white F-type main sequence dwarf with an apparent magnitude of +6.87.[1] The semimajor axis of its orbit is around 6.5 arcseconds, and it has an orbital period of around 2400 years around ι Cassiopeiae A, but the orbit is not very well constrained.[8] This object may be causing Kozai–Lidov cycles in the inner orbital pair.[8]

The third astrometric component, ι Cassiopeiae C, is another binary like ι Cassiopeiae A. It comprises two stars, a K-type star and a M-type star.[3] It orbits at an angular distance of 7 arcseconds from the A-B primary.[12] Since the semimajor axis of the A-B orbit is about 6.5 arcseconds, the true semimajor axis is thought to be significantly larger than 7 arcseconds.[8]

References[]

  1. ^ a b c d e f g h i j Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
  2. ^ a b c Drummond, Jack; Milster, Scott; Ryan, Patrick; Roberts, Jr., Lewis C. (2003). "ι Cassiopeiae: Orbit, Masses, and Photometry from Adaptive Optics Imaging in the I and H Bands". The Astrophysical Journal. 585 (2): 1007. Bibcode:2003ApJ...585.1007D. doi:10.1086/346224.
  3. ^ a b c d e f g Christou, Julian C.; Drummond, Jack D. (2006). "Measurements of Binary Stars, Including Two New Discoveries, with the Lick Observatory Adaptive Optics System". The Astronomical Journal. 131 (6): 3100. Bibcode:2006AJ....131.3100C. doi:10.1086/503255.
  4. ^ a b c d Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  5. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....1.2025S.
  6. ^ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
  7. ^ a b c van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  8. ^ a b c d e f g h i j k Tokovinin, A. (2021). "Inner and Outer Orbits in 13 Resolved Hierarchical Stellar Systems". The Astronomical Journal. 161 (3): 144. arXiv:2101.02976. Bibcode:2021AJ....161..144T. doi:10.3847/1538-3881/abda42. S2CID 231419112.
  9. ^ a b De Rosa, R. J.; Patience, J.; Vigan, A.; Wilson, P. A.; Schneider, A.; McConnell, N. J.; Wiktorowicz, S. J.; Marois, C.; Song, I.; MacIntosh, B.; Graham, J. R.; Bessell, M. S.; Doyon, R.; Lai, O. (2012). "The Volume-limited A-Star (VAST) survey - II. Orbital motion monitoring of A-type star multiples". Monthly Notices of the Royal Astronomical Society. 422 (4): 2765. arXiv:1112.3666. Bibcode:2012MNRAS.422.2765D. doi:10.1111/j.1365-2966.2011.20397.x. S2CID 102487103.
  10. ^ a b c d e f Aurière, M.; Wade, G. A.; Silvester, J.; Lignières, F.; Bagnulo, S.; Bale, K.; Dintrans, B.; Donati, J. F.; Folsom, C. P.; Gruberbauer, M.; Hui Bon Hoa, A.; Jeffers, S.; Johnson, N.; Landstreet, J. D.; Lèbre, A.; Lueftinger, T.; Marsden, S.; Mouillet, D.; Naseri, S.; Paletou, F.; Petit, P.; Power, J.; Rincon, F.; Strasser, S.; Toqué, N. (2007). "Weak magnetic fields in Ap/Bp stars". Astronomy and Astrophysics. 475 (3): 1053. arXiv:0710.1554. Bibcode:2007A&A...475.1053A. doi:10.1051/0004-6361:20078189. S2CID 54850596.
  11. ^ "* iot Cas". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 15 May 2017.
  12. ^ Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series. 124: 75–84. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181. (HR 707)


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