HR Lyrae

HR Lyrae or Nova Lyrae 1919 was a nova which occurred in the constellation Lyra in 1919. Its discovery was announced by Johanna C. Mackie on 6 December 1919. She discovered it while examining photographic plates taken at the Harvard College Observatory. The bulletin announcing the discovery (H.C.O. bulletin 705) states "Between December 4 and 6 it rose rapidly from the sixteenth magnitude or fainter, to a maximum of about 6.5". It was the first nova ever reported in Lyra, and Mackie was awarded the AAVSO gold medal for her discovery.[5][6] Its peak magnitude of 6.5 implies that it might have been visible to the naked eye, under ideal conditions.

HR Lyrae
Location of HR Lyrae (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lyra
Right ascension 18h 53m 25.0564s[1]
Declination +29° 13′ 37.6664″[1]
Apparent magnitude (V) 6.5 Max.
15.5 Min.[2]
Characteristics
Variable type Classical Nova[3]
Astrometry
Proper motion (μ) RA: −1.926±0.056[1] mas/yr
Dec.: −7.621±0.056[1] mas/yr
Parallax (π)0.1825 ± 0.0337[1] mas
Distance4797+1015
−470[2] pc
Other designations
Nova Lyrae 1919, Gaia DR2 2040551920255615104, HD 175268, 2MASS J18532505+2913377[4]
Database references
SIMBADdata
The light curve of HR Lyrae, plotted from data presented in Shears & Poyner (2007)[3]

HR Lyrae's outburst occurred in December 1919, when Lyra was only visible in the early evening for most northern observers. Visibility was even more limited in the first months of 1920, so its light curve near maximum brightness is poorly sampled. But it is very likely that it declined from peak brightness by 3 magnitudes in less than 100 days, making it a "fast" nova. By November 1921 the star had dimmed to 14th magnitude, which is close to its quiescent brightness. It continues to show brightness fluctuations of 1 magnitude or less above its quiescent magnitude with no clear periodicity,[3][7] as well as dimming (down to 17th magnitude) episodes.[8][9] Although only one nova event has been seen, there are suggestions based primarily on the light curve that HR Lyrae might be a recurrent nova.[10]

All novae are binary stars, with a "donor" star orbiting a white dwarf. The two stars are so close to each other that matter is transferred from the donor to the white dwarf. In the case of HR Lyrae the binary's orbital period is uncertain, but a value of 2.4 hours has been reported.[11] The white dwarf's mass has been estimated to be 0.78±0.15M☉[12]

References
  1. 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.
  2. Schaefer, Bradley E. (2018). "The distances to Novae as seen by Gaia". Monthly Notices of the Royal Astronomical Society. 481 (3): 3033–3051. arXiv:1809.00180. Bibcode:2018MNRAS.481.3033S. doi:10.1093/mnras/sty2388. S2CID 118925493.
  3. Shears, J.; Poyner, G. (June 2007). "HR Lyrae (Nova Lyr 1919): from outburst to active quiescence". Journal of the British Astronomical Association. 117 (3): 136–141. Retrieved 24 December 2020.
  4. "HR Lyrae". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-08-25.
  5. Duerbeck, Hilmar W. (March 1987). "A Reference Catalogue and Atlas of Galactic Novae". Space Science Reviews. 45 (1–2): 1–14. doi:10.1007/BF00187826. Retrieved 24 December 2020.
  6. Poyner, Gary. "Observing through the light". AAVSO CV Section. AAVSO. Retrieved 24 December 2020.
  7. Honeycutt, R.K.; Shears, J.; Kafka, S.; Robertson, J.W.; Henden, A.A. (May 2014). "The 1991-2012 Light Curve of the Old Nova HR LYRAE". The Astronomical Journal. 147 (5). doi:10.1088/0004-6256/147/5/105. Retrieved 25 December 2020.
  8. Shears, J.; Poyner, G. (December 2010). "A deep fade of HR Lyrae". Journal of the British Astronomical Association. 120. Retrieved 25 December 2020.
  9. Munari, U.; Siviero, A.; Ochner, P.; Dallaporta, S. (August 2016). "Spectroscopy and photometry of HR Lyr (Nova Lyr 1919) during one of its mysterious dimming episodes". The Astronomer's Telegram. 9418. Retrieved 25 December 2020.
  10. Pagnotta, Ashley; Schaefer, Bradley E. (June 2014). "Identifying and Quantifying Recurrent Novae Masquerading as Classical Novae". The Astrophysical Journal. 788 (2): 164. doi:10.1088/0004-637X/788/2/164. Retrieved 25 December 2020.
  11. Leibowitz, E.M.; Mendelson, H.; Gefen, G.; Retter, A. (January 1995). "Classical Novae as Wet Objects". Baltic Astronomy. 4: 453–466. doi:10.1515/astro-1995-0405. Retrieved 25 December 2020.
  12. Selvelli, Pierluigi; Gilmozzi, Roberto (February 2019). "A UV and optical study of 18 old novae with Gaia DR2 distances: mass accretion rates, physical parameters, and MMRD". Astronomy & Astrophysics. 622. doi:10.1051/0004-6361/201834238. Retrieved 25 December 2020.
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