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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	02 29 03.960
Declination	+67° 24′ 08.70″
Apparent magnitude (V)	4.61 (4.65 / 8.48)
ι Cas B
Right ascension	02 29 03.567
Declination	+67° 24′ 07.01″
Apparent magnitude (V)	6.87
ι Cas C
Right ascension	02 29 05.086
Declination	+67° 24′ 05.53″
Apparent magnitude (V)	9.05 (9.14 / 11.84)
Characteristics
U−B color index	+0.03
B−V color index	+0.12
ι Cas A
Spectral type	A3p / G6
Variable type	α CVn
ι Cas B
Spectral type	F5
ι Cas C
Spectral type	K4 / M2
U−B color index	+0.18
B−V color index	+0.72
Astrometry
Radial velocity (Rv)	1.2 ± 2 km/s
Proper motion (μ)	RA: -26.61 mas/yr Dec.: 38.21 mas/yr
Parallax (π)	22.22 ± 0.08 mas
Distance	146.8 ± 0.5 ly (45.0 ± 0.2 pc)
Absolute magnitude (MV)	1.62 ± 0.07 (Aa) 5.60 ± 0.17 (Ab)
Orbit
Primary	ι Cas Aa
Companion	ι 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
Primary	ι Cas A
Companion	ι 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
Mass	1.98 M☉
Radius	2.3 ± 0.4 R☉
Luminosity	24 L☉
Temperature	8360 ± 275 K
Rotation	1.74033 d
Rotational velocity (v sin i)	48 km/s
Age	100 Myr
ι Cas Ab
Mass	0.98 M☉
ι Cas B
Mass	1.28 M☉
Temperature	6540 K
ι Cas Ca
Temperature	4520 ± 20 K
ι Cas Cb
Temperature	3590 ± 45 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, making it visible to the naked eye. Based on its parallax, it is located about 133 light-years (41 parsecs) from Earth.

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. The primary is itself a tighter binary star system. The two stars were resolved by adaptive optics. These are designated Aa and Ab (although confusingly they may also be labeled as A and Aa, respectively). The primary is classified as an Alpha 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, because of its magnetic field. The variability in brightness was first detected by Karl D. Rakos in 1962, although its spectrum was known to be variable from earlier observations. The fainter companion is a G-type star with a mass of 0.98 M_☉. The orbital period of the system is about 49 years.

ι Cassiopeiae B is a yellow-white F-type main sequence dwarf with an apparent magnitude of +6.87. 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. This object may be causing Kozai–Lidov cycles in the inner orbital pair.

ι Cassiopeiae C is itself another binary, designated Ca and Cb, or just C and c. It comprises two stars, a K-type star and an M-type star. It is currently at an angular distance of about 7 arcseconds from the AB pair. 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.

References

1. ^ 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. ^ 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. ^ 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. ^ Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
5. ^ 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. ^ 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. ^ 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. ^ 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. ^ 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)

v t e Constellation of Cassiopeia
List of stars in Cassiopeia Cassiopeia in Chinese astronomy
Stars	Bayer α (Schedar) β (Caph) γ (Navi/Tsih) δ (Ruchbah) ε (Segin) ζ (Fulu) η (Achird) θ (Marfak) ι κ λ μ ν ξ ο π ρ σ τ υ υ (Castula) φ χ ψ ω Flamsteed 1 2 4 6 9 10 12 42 47 48 (A) 49 50 54 Variable R S TZ WZ YZ (21) AO AR PZ V373 V509 V547 V669 V705 V762 V863 V773 V987 V1022 V1405 HR 5 91 144 196 244 273 297 743 932 8832 8853 8881 HD 861 7924 7977 15558 17156 (Nushagak) 240210 240237 240429 240430 Other BD+60°2522 Gliese 49 IRAS 23304+6147 LS I +61 303 PSR J0205+6449 Tycho G 4U 0142+61 WR 2 WR 3
Exoplanets HD 7924 b HD 17156 b HD 219134 b c d e (h) f g HD 240210 b HD 240237 b
Star clusters Messier 52 Messier 103 NGC 103 NGC 110 NGC 129 NGC 133 NGC 136 NGC 146 NGC 189 NGC 225 NGC 358 NGC 366 NGC 381 NGC 433 NGC 436 NGC 457 NGC 559 NGC 637 NGC 654 NGC 659 NGC 663 NGC 1027 NGC 7789 NGC 7790 Trumpler 3
Nebulae	NGC 281 7635 Other 3C 58 Cassiopeia A Heart Nebula IC 289 IC 1805 KjPn 8 LBN 114.55+00.22 Sh 2-185 Westerhout 5
Galaxies	NGC 147 185 278 Other Andromeda VII 3C 20 3C 35 Dwingeloo 1 Dwingeloo 2 MB 3 IC 10 Maffei 1 Maffei 2 QSO B0153+744
Astronomical events SN 1181 SN 1572 (B)
Category

• Alpha2 Canum Venaticorum variables
• Bayer objects
• Cassiopeia (constellation)
• Multiple star systems
• Spectroscopic binaries
• A-type main-sequence stars
• F-type main-sequence stars
• G-type main-sequence stars
• Bright Star Catalogue objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Durchmusterung objects
• Ap stars