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) | −0.29 ± 0.23 mas[5] |
| 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
- ^ a b 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.
- ^ a b c 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. doi:10.1888/0333750888/2862.
- ^ a b c d e f g h 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.
- ^ a b c d 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: 432–445. arXiv:astro-ph/0503344. Bibcode:2005ApJ...627..432G. doi:10.1086/430265.
- ^ Gaia Collaboration (2016). "VizieR Online Data Catalog: Gaia DR1 (Gaia Collaboration, 2016)". VizieR On-line Data Catalog: I/337. Originally published in: Astron. Astrophys. 1337. Bibcode:2016yCat.1337....0G.
- ^ Morgenroth, O. (1935). "23 neue Veränderliche". Astronomische Nachrichten. 255 (23): 425–428. 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. Bibcode:2012A&A...548A..79A. doi:10.1051/0004-6361/201220095.
{{cite journal}}: Unknown parameter|class=ignored (help) - ^ Wenzel, W. (2013). "HP Lyrae -- the sudden period decrease". Minutes on Variable Stars (MVS13–01). Sonneberg Observatory.
- ^ 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.