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HR 4049

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HR 4049
Location of HR 4049 (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Antlia[1]
Right ascension 10h 18m 07.59s[2]
Declination −28° 59′ 31.2″[2]
Apparent magnitude (V) 5.29 – 5.83[3]
Characteristics
Evolutionary stage Post-AGB + main sequence[4]
Spectral type B9.5Ib-II[3]
B−V color index +0.24[5]
Variable type unique[3]
Astrometry
Radial velocity (Rv)−30.12±0.09[6] km/s
Proper motion (μ) RA: −16.290 mas/yr[2]
Dec.: +10.720 mas/yr[2]
Parallax (π)0.7107±0.0984 mas[2]
Distanceapprox. 4,600 ly
(approx. 1,400 pc)
Orbit[6]
Period (P)428.474±0.002 days
Eccentricity (e)0.29±0.01
Inclination (i)60–75°
Periastron epoch (T)2,458,383.2±0.6 HJD
Argument of periastron (ω)
(secondary)		242.3±0.3°
Semi-amplitude (K1)
(primary)		15.52±0.13 km/s
Details
A
Mass0.75±0.05[6] M☉
Radius76 ± 11[6][a] R☉
Luminosity16,600+5,300
−4,000[6] L☉
Surface gravity (log g)+1.0±0.5[4] cgs
Temperature7,500±500[6] K
Metallicity [Fe/H]−4.5[7] dex
B
Mass0.70–0.82[6] M☉
Radius0.6[4] R☉
Luminosity0.06[4] L☉
Surface gravity (log g)4.6[4] cgs
Temperature3,500[4] K
Other designations
AG Antliae, CD−28°8070, 2MASS J10180758-2859308, GSC 06630-01759, HD 89353, FK5 1265, PPM 257470, HIP 50456, SAO 178644, HR 4049
Database references
SIMBADdata

HR 4049, also known as HD 89353 and AG Antliae, is a binary post-asymptotic-giant-branch (post-AGB) star in the constellation Antlia. A very metal-poor star, it is surrounded by a thick unique circumbinary disk enriched in several molecules. With an apparent magnitude of about 5.5, the star can readily be seen with the naked eye under ideal conditions. It is located approximately 1,400 parsecs (4,600 ly) distant.

Characteristics

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HR 4049 has a peculiar spectrum. The star appears, based on its spectrum in the Balmer series, to be a blue supergiant, although in reality it is an old low-mass star on the post-AGB phase of its life. Its atmosphere is extremely deficient in heavy elements, over with a metallicity over 30,000 lower than the Sun.[8][9] It also shows a strong infrared excess, corresponding closely to a 1,200 K blackbody produced by a disk of material surrounding the star.[10] The star is also undergoing intense mass-loss[11] Its companion has only been detected from variations in the doppler shift of its spectral lines. It is thought to be a low luminosity main sequence star.[4]

Although HR 4049 A apparently has the spectrum of a blue supergiant, it is an old low-mass star which has exhausted nuclear fusion and is losing its outer layers as it transitions towards a white dwarf and possibly a planetary nebula. During this phase it has a luminosity several thousand times that of the Sun, although a mass around half that of the Sun. The mass can only be guessed from the expected mass of the white dwarf that it is becoming.[12]

Variability

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Light curve for HR 4049. The main plot shows the visual band brightness over one orbital period. The inset plot shows how the amplitude of the brightness change varies as a function of wavelength−1; as the observing wavelength increases, the opacity of the dust decreases, so the dust obscures less of the star's light. Adapted from Jorissen & Frankowski (2008)[13]

HR 4049 is an unusual variable star, ranging between magnitudes 5.29 and 5.83 with a period of 429 days.[14] It has been described as pulsating in a similar fashion to an RV Tauri variable,[15] although the preferred interpretation is that the variations are produced by variable extinction produced by the material around the star and that the period is the same as the orbital period.[4]

It was discovered to be a variable star by Christoffel Waelkens and Fredy Rufener in 1983[16] and was given the variable star designation AG Antliae in 1987,[17] but is still more commonly referred to as HR 4049.[6]

Notes

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  1. ^ Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:

References

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  1. ^ 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.
  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 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: B/GCVS. Bibcode:2009yCat....102025S.
  4. ^ a b c d e f g h Bakker; et al. (1998). "Spectral variability of the binary HR 4049". Astronomy and Astrophysics. 336 (1): 263–275. arXiv:astro-ph/9802120. Bibcode:1998A&A...336..263B.
  5. ^ Hoffleit, Dorrit; Jaschek, Carlos (1991). "The Bright star catalogue". New Haven. Bibcode:1991bsc..book.....H.
  6. ^ a b c d e f g h Nurmakhametova, Shakhida T.; Vaidman, Nadezhda L.; Miroshnichenko, Anatoly S.; Khokhlov, Azamat A.; Agishev, Aldiyar T.; Yermekbayev, Berik S.; Danford, Stephen; Aarnio, Alicia N. (2025-03-22). "HR 4049: A Spectroscopic Analysis of a Post-AGB Object". Galaxies. 13 (2): 26. Bibcode:2025Galax..13...26N. doi:10.3390/galaxies13020026. ISSN 2075-4434.
  7. ^ Kiss, L. L.; Derekas, A.; Szabó, Gy. M.; Bedding, T. R.; Szabados, L. (2007). "Defining the instability strip of pulsating post-AGB binary stars from ASAS and NSVS photometry". Monthly Notices of the Royal Astronomical Society. 375 (4): 1338–1348. arXiv:astro-ph/0612217. Bibcode:2007MNRAS.375.1338K. doi:10.1111/j.1365-2966.2006.11387.x. S2CID 14716983.
  8. ^ Waelkens, C.; Lamers, H.; Waters, R. (September 1987). "HR 4049 - an old low-mass star disguised as a young massive supergiant". ESO Messenger. 49: 29–32. Bibcode:1987Msngr..49...29W.
  9. ^ Takeda, Y.; Parthasarathy, M.; Aoki, W.; Ita, Y.; Nakada, Y.; Izumiura, H.; Noguchi, K.; Takada-Hidai, M.; Sato, B.; Tajitsu, A.; Honda, S.; Kawanomoto, S.; Ando, H.; Karoji, H. (2002). "Detection of Zinc in the Very Metal-Poor Post-AGB Star HR 4049". Publications of the Astronomical Society of Japan. 54 (5): 765. Bibcode:2002PASJ...54..765T. doi:10.1093/pasj/54.5.765.
  10. ^ Acke, B.; Degroote, P.; Lombaert, R.; De Vries, B. L.; Smolders, K.; Verhoelst, T.; Lagadec, E.; Gielen, C.; Van Winckel, H.; Waelkens, C. (2013). "Amorphous carbon in the disk around the post-AGB binary HR 4049". Astronomy & Astrophysics. 551: A76. Bibcode:2013A&A...551A..76A. doi:10.1051/0004-6361/201219282.
  11. ^ Geballe, T. R.; Noll, K. S.; Whittet, D. C. B.; Waters, L. B. F. M. (1989). "Unusual features of the 1-4 micron spectrum of HR 4049". The Astrophysical Journal. 340: L29. Bibcode:1989ApJ...340L..29G. doi:10.1086/185431.
  12. ^ Malek, S. E.; Cami, J. (2014). "The Gas-Rich Circumbinary Disk of Hr 4049. I. A Detailed Study of the Mid-Infrared Spectrum". The Astrophysical Journal. 780 (1): 41. arXiv:1310.6361. Bibcode:2014ApJ...780...41M. doi:10.1088/0004-637X/780/1/41. S2CID 118617900.
  13. ^ Jorissen, A.; Frankowski, A. (April 2008). "Detection methods of binary stars with low- and intermediate-mass components". AIP Conference Proceedings. 1057: 1–55. arXiv:0804.3720. Bibcode:2008AIPC.1057....1J. doi:10.1063/1.2999998. S2CID 7397204. Retrieved 14 October 2021.
  14. ^ VSX (4 January 2010). "AG Antliae". The International Variable Star Index. American Association of Variable Star Observers. Retrieved 15 June 2013.
  15. ^ Hillen, M.; Van Winckel, H.; Menu, J.; Manick, R.; Debosscher, J.; Min, M.; De Wit, W. -J.; Verhoelst, T.; Kamath, D.; Waters, L. B. F. M. (2017). "A mid-IR interferometric survey with MIDI/VLTI: Resolving the second-generation protoplanetary disks around post-AGB binaries". Astronomy and Astrophysics. 599: A41. arXiv:1610.09930. Bibcode:2017A&A...599A..41H. doi:10.1051/0004-6361/201629161. S2CID 119095913.
  16. ^ Waelkens, C.; Rufener, F. (1983). "The photometric variability of B stars - A general approach". Hvar Observatory Bulletin. 7 (1): 29–47. Bibcode:1983HvaOB...7...29W. Retrieved 12 November 2024.
  17. ^ Kholopov, P. N.; Samus, N. N.; Kazarovets, E. V.; Kireeva, N. N. (August 1987). "The 68th Name-List of Variable Stars". Information Bulletin on Variable Stars. 3058: 1. Bibcode:1987IBVS.3058....1K. Retrieved 12 November 2024.
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