HP Lyrae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 21m 39.066s[1] |
| Declination | +39° 56′ 08.05″[1] |
| Apparent magnitude (V) | 10.43[2] (10.2 - 10.8[3]) |
| Characteristics | |
| Spectral type | A2-F2 Iab[3] |
| U−B color index | +0.1 - +0.5[3] |
| B−V color index | +0.3 - +0.7[3] |
| Variable type | RV Tau[4] |
| Astrometry | |
| Radial velocity (Rv) | −107[4] km/s |
| Proper motion (μ) | RA: –3.1 ± 1.5[2] mas/yr Dec.: –3.3 ± 1.5[2] mas/yr |
| Parallax (π) | 39.60 ± 21.5[5] mas |
| Distance | ~5,000[3]) pc |
| Absolute magnitude (MV) | −4.5[3] |
| Details[4] | |
| Surface gravity (log g) | 1.0 cgs |
| Temperature | 6,300 K |
| Metallicity [Fe/H] | −1.0 dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
HP Lyrae is a variable star in the constellation Lyra, with a visual magnitude between 10.2 and 10.8.
HP Lyr was first reported to be variable in 1935 by Otto Morgenroth of the Sonneberg Observatory. The range was given as 9.5 - 10.5 and the variability type only as long-period.[6] In 1961, it was formally designated as a β Lyr eclipsing variable with two A type supergiants in a close orbit producing smooth continuous variations with alternating minima of different depths. The period was given as 140.75 days, covering two maxima, and both a deep primary minimum and a slightly less deep secondary minimum.[7]
In 2001 a request was made for observations of HP Lyr[8] and shortly after it was reported that HP Lyr was likely to be an RV Tauri variable rather than an eclipsing binary.[9] This was confirmed with a more detailed study published in 2002. [3] Some authors still maintain that the spectral type and nature of variation mean HP Lyr is more likely to be an eclipsing variable.[10]
HP Lyr varies by about 0.5 magnitude over a "halfperiod" of 69.35 days. The formal period, defined for an RV Tauri variable from deep minimum to deep minimum is 138.7 days. Its spectrum changes from A2-3 at maximum to F2 at the deepest minima. The radial velocity changes are typical for the pulsations of an RV Tauri variable, but not compatible with a binary orbit. The spectral type and colour indicated that it was likely to be the hottest known RV Tauri star.[3]
Until 1960, the period of HP Lyr was very consistent at 140.75 days. Since then it was observed to reduce to below 140 days, probably quite suddenly. A survey of historic photography including the star showed that the period changed in 1962 or 1963, taking no more than four cycles to reach a new value of 138.66 days.[11]
A study of the elemental abundances of RV Tauri stars calculated that HP Lyr had a temperature around 6,300 K and typical abundances for an RV Tauri variable. It also revealed that the abundances were altered by dust-gas separation in circumstellar material.[4] HP Lyr has been included in a catalog of confirmed post-AGB stars, highly evolved and on its way to becoming a white dwarf.[12]
References
- 1 2 Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; Carpenter, J. M.; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; Huchra, J.; Jarrett, T.; Kopan, E. L.; Kirkpatrick, J. D.; Light, R. M.; Marsh, K. A.; McCallon, H.; Schneider, S.; Stiening, R.; Sykes, M.; Weinberg, M.; Wheaton, W. A.; Wheelock, S.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog: II/246. Originally published in: 2003yCat.2246....0C 2246. Bibcode:2003yCat.2246....0C.
- 1 2 3 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27. Bibcode:2000A&A...355L..27H.
- 1 2 3 4 5 6 7 8 Graczyk, D.; Mikolajewski, M.; Leedjarv, L.; Frackowiak, S. M.; Osiwala, J. P.; Puss, A.; Tomov, T. (2002). "HP Lyr - Possibly the Hottest RV Tau Type Object". Acta Astronomica 52: 293–304. arXiv:astro-ph/0210448. Bibcode:2002AcA....52..293G.
- 1 2 3 4 Giridhar, Sunetra; Lambert, David L.; Reddy, Bacham E.; Gonzalez, Guillermo; Yong, David (2005). "Abundance Analyses of Field RV Tauri Stars. VI. An Extended Sample". The Astrophysical Journal 627: 432. arXiv:astro-ph/0503344. Bibcode:2005ApJ...627..432G. doi:10.1086/430265.
- ↑ ESA (1997). "The HIPPARCOS and TYCHO catalogues. Astrometric and photometric star catalogues derived from the ESA HIPPARCOS Space Astrometry Mission". The Hipparcos and Tycho catalogues. Astrometric and photometric star catalogues derived from the ESA Hipparcos Space Astrometry Mission 1200. Bibcode:1997HIP...C......0E.
- ↑ Morgenroth, O. (1935). "23 neue Veränderliche". Astronomische Nachrichten 255 (23): 425. Bibcode:1935AN....255..425M. doi:10.1002/asna.19352552303.
- ↑ Wenzel, W. (1961). "Two Variables of Beta Lyrae Type with Long Periods". Information Bulletin on Variable Stars 1: 1. Bibcode:1961IBVS....1....1W.
- ↑ Meyer, R. (2001). "Beobachtungsaufruf: HP Lyr". BAV Rundbrief 50: 5. Bibcode:2001BAVSR..50....5M.
- ↑ Hassforther, B. (2002). "HP Lyrae ist wahrscheinlich ein RV-Tauri-Stern". BAV Rundbrief 51: 182. Bibcode:2002BAVSR..51..182H.
- ↑ Alfonso-Garzón, J.; Domingo, A.; Mas-Hesse, J. M.; Giménez, A. (2012). "The first INTEGRAL-OMC catalogue of optically variable sources". Astronomy & Astrophysics 1210: arXiv:1210.0821. arXiv:1210.0821 [astro-ph.IM]. Bibcode:2012arXiv1210.0821A. doi:10.1051/0004-6361/201220095.
- ↑ Wenzel, W. (2013). "HP Lyrae -- the sudden period decrease". Minutes on Variable Stars (Sonneberg Observatory) (MVS13–01).
- ↑ Szczerba, R.; Siódmiak, N.; Stasińska, G.; Borkowski, J. (2007). "An evolutionary catalogue of galactic post-AGB and related objects". Astronomy and Astrophysics 469 (2): 799–806. Bibcode:2007A&A...469..799S. doi:10.1051/0004-6361:20067035.
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