DL Crucis

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DL Crucis
Crux constellation map.svg
Red circle.svg
Location of DL Crucis (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Crux
Right ascension 12h 14m 16.9255s [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 (Rv)-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  (MV)−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.

Contents

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 DLCruLightCurve.png
A light curve for DL Crucis, plotted from Hipparcos data

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

  1. 1 2 3 4 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.
  2. 1 2 3 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.
  3. 1 2 3 4 5 6 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.
  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. 1: 02025. Bibcode:2009yCat....102025S.
  5. ↑ 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.
  6. ↑ 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.
  7. 1 2 3 4 5 6 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.
  8. ↑ 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.
  9. ↑ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
  10. ↑ Balona, L. A. (1977). "A search for Beta Canis Majoris stars". Memoirs of the Royal Astronomical Society. 84: 101. Bibcode:1977MmRAS..84..101B.
  11. ↑ 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 .
  12. ↑ 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.
  13. ↑ 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.
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