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Iota Cassiopeiae

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ι Cassiopeiae

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 mas[8]
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
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,[citation needed] making it visible to the naked eye. Based on its parallax, it is located about 133 light-years (41 parsecs) from Earth.[7]

Components

[edit]
A light curve for Iota Cassiopeiae, plotted from TESS data[11]

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 is itself a tighter binary star system. The two stars were resolved by adaptive optics.[citation needed] These are designated Aa and Ab (although confusingly they may also be labeled as A and Aa, respectively).[citation needed] 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 variability in brightness was first detected by Karl D. Rakos in 1962, although its spectrum was known to be variable from earlier observations.[12] 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]

ι Cassiopeiae B is a yellow-white F-type main sequence dwarf with an apparent magnitude of +6.87.[1] It orbits around ι Cassiopeiae A approximately every 2,400 years with a semi-major axis of around 6.5 arcseconds, but the orbit is not very well constrained.[8] This object may be causing Kozai–Lidov cycles in the inner orbital pair.[8]

ι Cassiopeiae C is itself another binary, designated Ca and Cb,[8] or just C and c.[3] It comprises two stars, a K-type star and an M-type star.[3] It is currently at an angular distance of about 7 arcseconds from the AB pair.[13] Since the semimajor axis of the AB orbit is about 6.5 arcseconds, the true semimajor axis of C's orbit around them is thought to be significantly larger than 7 arcseconds.[8]

References

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  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 h 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....102025S.
  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 l 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. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  12. ^ Rakos, Karl D. (1962). "Photoelectric investigation of magnetic and spectrum variable stars". Bulletin / Lowell Observatory. 5 (12): 227–256. Bibcode:1962LowOB...5..227R. Retrieved 10 October 2024.
  13. ^ 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 Archived 2021-02-05 at the Wayback Machine)
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