DU Crucis

DU Crucis is a red supergiant and slow irregular variable star in the open cluster NGC 4755, which is also known as the Kappa (κ) Crucis Cluster or Jewel Box Cluster.

DU Crucis

The centre of NGC 4755, with DU Cru at top right
Credit: NASA/ESA and Jesús Maíz Apellániz (Instituto de Astrofísica de Andalucía, Spain)
Observation data
Epoch J2000      Equinox J2000
Constellation Crux
Right ascension  12h 53m 41.33485s[1]
Declination −60° 20′ 57.9647″[1]
Apparent magnitude (V) 7.45[2]
Characteristics
Spectral type M2- Iab[3]
U−B color index +2.57[2]
B−V color index +2.22[2]
Variable type Lc[4]
Astrometry
Radial velocity (Rv)−21.24[5] km/s
Proper motion (μ) RA: −4.703[6] mas/yr
Dec.: −1.162[6] mas/yr
Parallax (π)0.5075 ± 0.0516[6] mas
Distance2,600[7][8] pc
Absolute magnitude (MV)−5.52[9]
Details[9]
Radius568[10] R☉
Luminosity52,000 - 53,000[10] L☉
Temperature3,660±170[10] K
Other designations
DU Cru, CD−59°4459, HIP 62918, SAO 252073, 2MASS J12534132-6020578, IRAS 12506-6004
Database references
SIMBADdata

Location
A Snapshot of the Jewel Box cluster (Credit: ESO VLT).

DU Crucis is one of the brighter members of the Jewel Box Cluster and the brightest red supergiant, strongly contrasting with the other bright members which are blue supergiants.[11] It is part of the central bar of the prominent letter "A"-shaped asterism at the centre of the cluster. The cluster is part of the larger Centaurus OB1 association and lies about 8,500 light years away.

The cluster is just to the south-east of β Crucis, the lefthand star of the Southern Cross.

Properties

DU Crucis is an M2 intermediate luminosity supergiant (luminosity class Iab). Despite its low temperature, it is 46,600 times the luminosity of the sun, due to its very large size. The κ Crucis cluster has a calculated age of 11.2 million years.[7]

Variability

Photometry from the Hipparcos satellite mission showed that DU Crucis varies in brightness with an amplitude of 0.44 magnitudes.[12] No periodicity could be detected in the variations and it was classified as a slow irregular variable of type Lc, indicating a supergiant.[4]

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References
  1. van Leeuwen, F. (November 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.
  2. Dachs, J.; Kaiser, D. (November 1984), "UBV photometry of the southern galactic cluster NGC 4755 = Kappa Crucis", Astronomy and Astrophysics Supplement Series, 58: 411–429, Bibcode:1984A&AS...58..411D.
  3. 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. ISSN 0067-0049.
  4. 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.
  5. Mermilliod, J. C.; Mayor, M.; Udry, S. (2008). "Red giants in open clusters. XIV. Mean radial velocities for 1309 stars and 166 open clusters". Astronomy and Astrophysics. 485 (1): 303–314. Bibcode:2008A&A...485..303M. CiteSeerX 10.1.1.30.7545. doi:10.1051/0004-6361:200809664.
  6. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  7. Aidelman, Y.; Cidale, L. S.; Zorec, J.; Arias, M. L. (2012). "Open clusters. I. Fundamental parameters of B stars in NGC 3766 and NGC 4755". Astronomy & Astrophysics. 544: A64. Bibcode:2012A&A...544A..64A. doi:10.1051/0004-6361/201219069.
  8. Corti, M. A.; Orellana, R. B. (2013). "Members of Centaurus OB1 and NGC 4755: New spectroscopic and astrometric studies". Astronomy & Astrophysics. 553: A108. Bibcode:2013A&A...553A.108C. doi:10.1051/0004-6361/201220743.
  9. Harris, G. L. H. (1976). "Evolved stars in open clusters". Astrophysical Journal. 30: 451. Bibcode:1976ApJS...30..451H. doi:10.1086/190368.
  10. Messineo, M.; Brown, A. G. A. (2019). "A Catalog of Known Galactic K-M Stars of Class I Candidate Red Supergiants in Gaia DR2". The Astronomical Journal. 158 (1): 20. arXiv:1905.03744. Bibcode:2019AJ....158...20M. doi:10.3847/1538-3881/ab1cbd.
  11. Kharchenko, N. V.; Piskunov, A. E.; Röser, S.; Schilbach, E.; Scholz, R.-D. (2004). "Astrophysical supplements to the ASCC-2.5. II. Membership probabilities in 520 Galactic open cluster sky areas". Astronomische Nachrichten. 325 (9): 740–748. Bibcode:2004AN....325..740K. doi:10.1002/asna.200410256.
  12. Adelman, Saul J. (2001). "Stars with the Largest Hipparcos Photometric Amplitudes". Baltic Astronomy. 10 (4): 589. Bibcode:2001BaltA..10..589A. doi:10.1515/astro-2001-0403.
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