HD 28843

HD 28843, also known as HR 1441 and DZ Eridani, is a star about 550 light years from the Earth, in the constellation Eridanus.[1] It is a 5th magnitude star, so it will be faintly visible to the naked eye of an observer far from city lights. It is a variable star, whose brightness varies slightly from 5.70 to 5.84 during its 1.374 day rotation period.[2][9] It is a member of the μ Tauri Association, a group of young stars within the larger Cassiopeia-Taurus Structure.[3]

HD 28843
Location of HD 28843 (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Eridanus
Right ascension 04h 32m 37.55373s[1]
Declination −03° 12′ 34.3448″[1]
Apparent magnitude (V) 5.70 - 5.84[2]
Characteristics
Spectral type B9III[3]
U−B color index −0.55[4]
B−V color index −0.14[4]
Variable type SX Arietis[5]
Astrometry
Radial velocity (Rv)18±7[3] km/s
Proper motion (μ) RA: 18.227±0.068[1] mas/yr
Dec.: −16.177±0.054[1] mas/yr
Parallax (π)5.8958 ± 0.0608 mas[1]
Distance553 ± 6 ly
(170 ± 2 pc)
Absolute magnitude (MV)−0.7[6]
Details
Mass4.20±0.6[7] M☉
Radius3.4[1] R☉
Luminosity324+57
−48[7] L☉
Surface gravity (log g)3.86[1] cgs
Temperature14800±200[7] K
Metallicity [Fe/H]−0.166[8] dex
Rotation1.37381±0.00001 d[9]
Rotational velocity (v sin i)91[7] km/s
Other designations
DZ Eri, HR 1441, HIP 21192, SAO 131279[10]
Database references
SIMBADdata
A light curve for DZ Eridani, plotted from TESS data[11]

In 1969 Mercedes Jaschek et al. determined that HD 28843 is a helium-weak star, based on its B-V color index being bluer (more negative) than would be expected for a star with its spectral type.[12] In 1977, Robert Davis reported that the star has an overabundance of silicon.[13] It is classified as a chemically peculiar star.[14]

Henning Jorgensen et al. reported that HD 28843 was a "suspected variable star" in 1971.[15] The variability of the star was firmly established in 1977 by Holger Pedersen and Bjarne Thomsen, during a spectroscopic and photometric study of helium weak and helium strong stars. They determined its period to be 1.374±0.006 days.[16] In 1978 the star was given the variable star designation DZ Eridani.[17]

Ermanno Borra et al. reported in 1983 the detection of the magnetic field of HD 28843, and estimated its strength to be a few hundred gauss.[18] Later data from the International Ultraviolet Explorer implied a field strength of 250 gauss.[19]

M. Farthmann et al. reported in 1994 that high spectral resolution observations of the 4471Å spectral line of neutral helium can be explained if HD 28843 has two helium-enriched circular "caps" separated by a region with a dramatically lower helium abundance.[20]

References
  1. 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.
  2. Manfroid, J.; Mathys, G. (July 1984). "On the Photometric Variations of HD 28843 and HD 29009" (PDF). Information Bulletin on Variable Stars. 2551: 1. Bibcode:1984IBVS.2551....1M. Retrieved 4 March 2023.
  3. Gagné, Jonathan; David, Trevor J.; Mamajek, Eric E.; Mann, Andrew W.; Faherty, Jacqueline K.; Bédard, Antoine (November 2020). "The μ Tau Association: A 60 Myr Old Coeval Group at 150 pc from the Sun". The Astrophysical Journal. 903 (2): 96. arXiv:2008.06139. Bibcode:2020ApJ...903...96G. doi:10.3847/1538-4357/abb77e.
  4. Feinstein, A. (April 1978). "Photoelectric measures of hydrogen lines in helium-weak stars". Revista Mexicana de Astronomía y Astrofísica. 2: 331–337. Bibcode:1978RMxAA...2..331F.
  5. Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
  6. Eggen, O. J. (April 1977). "Is star formation bimodal? II. The nearest early-type stars". Publications of the Astronomical Society of the Pacific. 89: 187–204. Bibcode:1977PASP...89..187E. doi:10.1086/130099.
  7. Shultz, M. E.; Owocki, S. P.; ud-Doula, A.; Biswas, A.; Bohlender, D.; Chandra, P.; Das, B.; David-Uraz, A.; Khalack, V.; Kochukhov, O.; Landstreet, J. D.; Leto, P.; Monin, D.; Neiner, C.; Rivinius, Th.; Wade, G. A. (June 2022). "MOBSTER - VI. The crucial influence of rotation on the radio magnetospheres of hot stars". Monthly Notices of the Royal Astronomical Society. 513 (1): 1429–1448. arXiv:2201.05512. Bibcode:2022MNRAS.513.1429S. doi:10.1093/mnras/stac136.
  8. Cardiel, Nicolás; Zamorano, Jaime; Carrasco, Josep Manel; Masana, Eduard; Bará, Salvador; González, Rafael; Izquierdo, Jaime; Pascual, Sergio; Sánchez de Miguel, Alejandro (23 July 2021). "RGB photometric calibration of 15 million Gaia stars". Monthly Notices of the Royal Astronomical Society. 507 (1): 318–329. arXiv:2107.08734. Bibcode:2021MNRAS.507..318C. doi:10.1093/mnras/stab2124. eISSN 1365-2966. ISSN 0035-8711.
  9. Waelkens, C. (July 1985). "Photometric variations and period determination of eight southern CP stars". Astronomy and Astrophysics Supplement Series. 61: 127–139. Bibcode:1985A&AS...61..127W.
  10. "HD 28843 -- Rotating Variable". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-03-03.
  11. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 3 March 2023.
  12. Jaschek, Mercedes; Jaschek, Carlos; Arnal, Marcelo (October 1969). "Helium-Weak Stars". Publications of the Astronomical Society of the Pacific. 81 (482): 650–656. Bibcode:1969PASP...81..650J. doi:10.1086/128832.
  13. Davis, R. J. (April 1977). "Spectral classification and U, B, V, Hbeta photometry". Astrophysical Journal. 213: 105–110. Bibcode:1977ApJ...213..105D. doi:10.1086/155134.
  14. Bonsack, W. K.; Dyck, H. M. (September 1983). "Infrared colors of the chemically peculiar stars of the upper main sequence". Astronomy and Astrophysics. 125: 29–33. Bibcode:1983A&A...125...29B.
  15. Jørgensen, H. E.; Johansen, K. T.; Olsen, E. H. (May 1971). "Variability of A and F main sequence stars". Astronomy and Astrophysics. 12: 223–231. Bibcode:1971A&A....12..223J.
  16. Pedersen, H.; Thomsen, B. (October 1977). "Spectrum and photometric variability of He-weak and He-strong stars". Astronomy and Astrophysics Supplement Series. 30: 11–25. Bibcode:1977A&AS...30...11P.
  17. Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (April 1979). "64th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 1581: 1. Bibcode:1979IBVS.1581....1K. Retrieved 25 February 2023.
  18. Borra, E. F.; Landstreet, J. D.; Thompson, I. (September 1983). "The magnetic fields of the helium-weak B stars". Astrophysical Journal Supplement Series. 53: 151–167. Bibcode:1983ApJS...53..151B. doi:10.1086/190889.
  19. Brown, D. N.; Shore, S. N.; Barker, P. K.; Sonneborn, G. (December 1984). "Magnetospheres and winds in the helium weak stars: observations of C IV in upper main sequence CP stars". NASA Conference Publication. 2349: 487–490. Bibcode:1984NASCP2349..487B.
  20. Farthmann, M.; Dreizler, S.; Heber, U.; Hunger, K. (November 1994). "Stratification of helium in the photospheres of the helium-weak stars HD 28843 and HD 49333". Astronomy and Astrophysics. 291: 919–927. Bibcode:1994A&A...291..919F.
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