Iota Cancri

ι Cancri
Location of ι Cancri (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cancer[1]
ι Cnc A
Right ascension 08h 46m 41.820s[2]
Declination +28° 45′ 35.62″[2]
Apparent magnitude (V) 4.03[1]
ι Cnc B
Right ascension 08h 46m 39.980s[3]
Declination +28° 45′ 54.21″[3]
Apparent magnitude (V) 6.58[4]
Characteristics
ι Cnc A
Spectral type G8IIIa Ba0.2[5]
B−V color index 1.007±0.015[1]
ι Cnc B
Evolutionary stage main sequence[3]
Spectral type A2V[6]
B−V color index 0.051±0.008[4]
Astrometry
ι Cnc A
Radial velocity (Rv)15.74±0.13[7] km/s
Proper motion (μ) RA: −22.070 mas/yr[2]
Dec.: −43.699 mas/yr[2]
Parallax (π)9.4124±0.1621 mas[2]
Distance347 ± 6 ly
(106 ± 2 pc)
Absolute magnitude (MV)−0.79[8]
ι Cnc B
Radial velocity (Rv)25.00±1.5[9] km/s
Proper motion (μ) RA: −24.397 mas/yr[3]
Dec.: −44.250 mas/yr[3]
Parallax (π)9.6720±0.0362 mas[3]
Distance337 ± 1 ly
(103.4 ± 0.4 pc)
Details
ι Cnc A
Mass2.376±0.011[10] M☉
Radius21[7] R☉
Luminosity204[7] L☉
Surface gravity (log g)2.5[7] cgs
Temperature4,954[8] K
Metallicity [Fe/H]−0.14[7] dex
ι Cnc B
Mass2.113±0.035[10] M☉
Radius1.94±0.05[11] R☉
Luminosity24.9±1.2[11] L☉
Surface gravity (log g)4.23±0.06[11] cgs
Temperature9,259±139[11] K
Rotational velocity (v sin i)170[12] km/s
Age263[13] Myr
Other designations
ι Cancri, 48 Cancri, WDS J08467+2846[14]
Iota Cancri A: Yuyu, NSV 4238, BD+29°1824, FK5 328, GC 12083, HD 74739, HIP 43103, HR 3475, SAO 80416[14]
Iota Cancri B: BD+29°1823, GC 12080, HD 74738, HIP 43100, HR 3474, SAO 80415, TIC 117355623[15]
Database references
SIMBADA
B

Iota Cancri, also named Yuyu,[16] is a double star in the constellation Cancer. The brighter component is located at a distance of approximately 347 light-years (106 pc) from Earth based on parallax measurements, and is drifting further away with a line of sight velocity of 16 km/s.[7]

The two stars of ι Cancri are separated by 30.5 arcseconds as of 2019, corresponding to a projected separation of 3,236 AU (0.05 ly).[10] Although no orbit has been derived, the pair show a large common proper motion and are assumed to be gravitationally related.[17]

Nomenclature

ι Cancri (Latinised to Iota Cancri, abbreviated ι Cnc or Iota Cnc) is the star's Bayer designation.

In Bali (Indonesia), the constellation Cancer is called Yuyu. Yuyu is a word from Javanese that means freshwater crab, inherited from Old Javanese hayuyu, spoken on the island of Java. The animal can be found in rice fields in Indonesia and the constellation is attested for at least 1300 years.[18] The IAU Working Group on Star Names approved the name Yuyu for Iota Cancri A on 22 February 2026.[16]

ι Cancri together with α Cancri were known in Arabic as Al Zubanāh, the claws (of the crab),[19] originating in translation of Ptolemy's Tetrabiblos.[20] This is the source of the modern name Acubens for α Cancri;[20] a 1971 NASA catalog of star names also used the name Zubanah for ι Cancri.[21]

Properties

The brighter star, ι Cancri A, is a yellow G-type giant with a stellar classification of G8IIIa Ba0.2[5] and an apparent visual magnitude of +4.03.[1] The suffix notation 'Ba0.2' indicates this is a mild barium star, thought to be caused by mass transfer of enriched material from an asymptotic giant branch star onto a less evolved companion. No such donor has been detected in the ι Cancri system, but it is assumed that there is an unseen white dwarf.[22]

This star has 2.4[10] times the mass of the Sun and has expanded to 21 times the Sun's radius.[7] It is radiating 204[7] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,954 K.[8]

The fainter of the two stars, ι Cancri B, is a white A-type main-sequence star with a class of A2V[6] and an apparent magnitude of +6.58.[4] The star has 2.1[10] times the Sun's mass and 1.9 times the Sun's radius.[11] It is radiating 25 times the luminosity of the Sun from its photosphere at an effective temperature of 9,259 K.[11] With an estimated age of 263[13] million years, it is spinning rapidly with a projected rotational velocity of 170 km/s.[12] This is a shell star, surrounded by material expelled by its rapid rotation.[23]

References

  1. ^ a b c d Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
  2. ^ a b c d Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  4. ^ a b c Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
  5. ^ a b Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373. S2CID 123149047.
  6. ^ a b Grenier, S.; et al. (1999). "Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS" (PDF). Astronomy and Astrophysics Supplement. 137 (3): 451. Bibcode:1999A&AS..137..451G. doi:10.1051/aas:1999489.
  7. ^ a b c d e f g h Massarotti, Alessandro; et al. (2008). "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity". The Astronomical Journal. 135 (1): 209–231. Bibcode:2008AJ....135..209M. doi:10.1088/0004-6256/135/1/209.
  8. ^ a b c Kovtyukh, V. V.; et al. (2010). "Accurate luminosities for F-G supergiants from FeII/FeI line depth ratios". Monthly Notices of the Royal Astronomical Society. 408 (3): 1568. Bibcode:2010MNRAS.408.1568K. doi:10.1111/j.1365-2966.2010.17217.x.
  9. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  10. ^ a b c d e Jiménez-Esteban, F. M.; et al. (February 2019). "A Catalog of Wide Binary and Multiple Systems of Bright Stars from Gaia-DR2 and the Virtual Observatory". The Astronomical Journal. 157 (2): 78. arXiv:1901.03730. Bibcode:2019AJ....157...78J. doi:10.3847/1538-3881/aafacc. 78.
  11. ^ a b c d e f Stassun, Keivan G.; et al. (September 9, 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881.
  12. ^ a b Royer, F.; et al. (2002). "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i". Astronomy and Astrophysics. 393 (3): 897–912. arXiv:astro-ph/0205255. Bibcode:2002A&A...393..897R. doi:10.1051/0004-6361:20020943. S2CID 14070763.
  13. ^ a b Takeda, Yoichi; et al. (2008). "Stellar Parameters and Elemental Abundances of Late-G Giants". Publications of the Astronomical Society of Japan. 60 (4): 781. arXiv:0805.2434. Bibcode:2008PASJ...60..781T. doi:10.1093/pasj/60.4.781. S2CID 16258166.
  14. ^ a b "iot Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2025-06-22.
  15. ^ "iot Cnc B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2025-06-22.
  16. ^ a b "IAU Catalog of Star Names". Retrieved 22 February 2026.
  17. ^ Eggen, Olin J. (1994). "Photometry of F-K type bright giants and supergiants. 3: The luminosity, reddening, and heavy element abundance of GK stars". The Astronomical Journal. 107: 2184. Bibcode:1994AJ....107.2184E. doi:10.1086/117030.
  18. ^ "Yuyu". All Skies Encyclopaedia. IAU Working Group on Star Names. Retrieved 22 February 2026.
  19. ^ Allen, R. H. (1899), Star Names: Their Lore and Meaning, p. 111
  20. ^ a b "Acubens". All Skies Encyclopaedia. IAU Working Group on Star Names. Retrieved 22 February 2026.
  21. ^ Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars (PDF), Jet Propulsion Laboratory, California Institute of Technology.
  22. ^ Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  23. ^ Hauck, B.; Jaschek, C. (2000). "A-shell stars in the Geneva system". Astronomy and Astrophysics. 354: 157. Bibcode:2000A&A...354..157H.
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