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DL Crucis - Wikipedia

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DL Crucis
Observation data Epoch J2000 Equinox J2000
Location of DL Crucis (circled)
Constellation	Crux
Right ascension	12^h 14^m 16.9255^s^[1]
Declination	−64° 24′ 30.662″^[1]
Apparent magnitude (V)	6.18^[2]
Characteristics
Spectral type	B1.5Ia^[3]
U−B color index	−0.73^[2]
B−V color index	0.12^[2]
Variable type	α Cygni^[4]
Astrometry

Radial velocity (R_v)	-10.50^[5] km/s
Proper motion (μ)	RA: -5.62^[1] mas/yr Dec.: 0.15^[1] mas/yr
Parallax (π)	0.80 ± 0.30 mas^[6]
Distance	approx. 4,000 ly (approx. 1,300 pc)
Absolute magnitude (M_V)	−6.9^[7]

Details

Mass	30^[3] `M`_☉
Radius	42^[7] `R`_☉
Luminosity	251,000^[7] `L`_☉
Surface gravity (log g)	2.50^[3] cgs
Temperature	20,100^[3] K
Rotational velocity (v sin i)	43^[3] km/s

Other designations
DL Cru, HIP 59678, HD 106343, CD-63° 732, HR 4653, GSC 08982-04743, CPD-63° 2203, GC 16707, SAO 251803
Database references
SIMBAD	data

DL Crucis is a variable star in the constellation Crux.

Visibility

DL Crucis has a visual apparent magnitude of 6.3 so it is just visible with the unaided eye in dark skies.^[8] It lies in the small southern constellation of Crux, halfway between η Crucis and ζ Crucis and close to the constellation's brightest star α Crucis. This area of sky lies within the Milky Way and close to the Coalsack Nebula.

Properties

DL Crucis has a spectral type of B1.5 Ia, making it a luminous blue supergiant with a temperature over 20,000 K and 251,000 times as luminous as the sun.^[7] It has a radius around 42 times,^[7] and a mass 30 times that of the Sun.^[3]

Variability

A light curve for DL Crucis, plotted from *Hipparcos* data^[9]

In 1977 DL Crucis, then referred to as HR 4653, was being used as a comparison star to test the variability of δ Crucis. δ Crucis turned out to be constant relative to several other stars, but the difference in brightness between it and HR 4653 changed by 0.02 magnitude.^[10] It was considered likely to be a variable with a period longer than seven hours.^[11]

Hipparcos photometry showed that DL Crucis was varying by up to 0.04 magnitude with a main period of 2 days 21 hours It was classified as an α Cygni variable.^[12] Shortly afterwards it received its variable star designation of DL Crucis.^[13]

A later detailed statistical analysis of the same data found periods of 3.650 and 3.906 days, as well as a first harmonic pulsation, with a maximum brightness range of 0.11 magnitudes.^[7]

References

^ ^a ^b ^c ^d Van Leeuwen, F. (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.
^ ^a ^b ^c Schild, R. E.; Garrison, R. F.; Hiltner, W. A. (1983). "UBV photometry for southern OB stars". The Astrophysical Journal Supplement Series. 51: 321. Bibcode:1983ApJS...51..321S. doi:10.1086/190852. ISSN 0067-0049.
^ ^a ^b ^c ^d ^e ^f Fraser, M.; Dufton, P. L.; Hunter, I.; Ryans, R. S. I. (2010). "Atmospheric parameters and rotational velocities for a sample of Galactic B-type supergiants". Monthly Notices of the Royal Astronomical Society. 404 (3): 1306. arXiv:1001.3337. Bibcode:2010MNRAS.404.1306F. doi:10.1111/j.1365-2966.2010.16392.x. ISSN 0035-8711. S2CID 118674151.
^ 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. 1: 02025. Bibcode:2009yCat....102025S.
^ 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. ISSN 1063-7737. S2CID 119231169.
^ Gaia Collaboration (2016). "VizieR Online Data Catalog: Gaia DR1 (Gaia Collaboration, 2016)". VizieR On-line Data Catalog. 1337. Bibcode:2016yCat.1337....0G. doi:10.26093/cds/vizier.1337.
^ ^a ^b ^c ^d ^e ^f Lefever, K.; Puls, J.; Aerts, C. (2007). "Statistical properties of a sample of periodically variable B-type supergiants. Evidence for opacity-driven gravity-mode oscillations". Astronomy and Astrophysics. 463 (3): 1093. arXiv:astro-ph/0611484. Bibcode:2007A&A...463.1093L. doi:10.1051/0004-6361:20066038. S2CID 8783008.
^ Bortle, John E. (February 2001). "The Bortle Dark-Sky Scale". Sky & Telescope. Sky Publishing Corporation. Archived from the original on 31 March 2014. Retrieved 28 June 2014.
^ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
^ Balona, L. A. (1977). "A search for Beta Canis Majoris stars". Memoirs of the Royal Astronomical Society. 84: 101. Bibcode:1977MmRAS..84..101B.
^ Jakate, S. M. (1979). "A search for Beta Cephei stars. III - Photometric studies of southern B-type stars". Astronomical Journal. 84: 552. Bibcode:1979AJ.....84..552J. doi:10.1086/112448.
^ Waelkens, C.; Aerts, C.; Kestens, E.; Grenon, M.; Eyer, L. (1998). "Study of an unbiased sample of B stars observed with Hipparcos: The discovery of a large amount of new slowly pulsating B stars". Astronomy and Astrophysics. 330: 215. Bibcode:1998A&A...330..215W.
^ Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Frolov, M. S.; Antipin, S. V.; Kireeva, N. N.; Pastukhova, E. N. (1999). "The 74th Special Name-list of Variable Stars". Information Bulletin on Variable Stars. 4659: 1. Bibcode:1999IBVS.4659....1K.

Constellation of Crux

Stars

Bayer	α (Acrux) β (Mimosa) γ (Gacrux) δ (Imai) ε (Ginan) ζ η θ¹ θ² ι λ μ¹ μ²
Variable	R S T V W X BG BH BL BP BU BZ CD CH DL DS DU
HR	4729 4848 4887 4890
HD	106906 108147 (Tupã)
Other	NGC 4349-127 PSR B1259−63/LS 2883 WR 46

Exoplanets	HD 106906 b HD 108147 b

Star clusters	Dragonfish Nebula Jewel Box (κ) NGC 4103 NGC 4349 NGC 4609

Nebulae	Coalsack Nebula Dragonfish Nebula IRAS 12063-6259