NY Virginis
NY Virginis is a binary star about 1,940 light-years away. The primary belongs to the rare class of subdwarf B stars, being former red giants with their hydrogen envelope completely stripped by a stellar companion. The companion is a red dwarf star.[8] The binary nature of NY Virginis was first identified in 1998,[9] and the extremely short orbital period of 0.101016 d, together with brightness variability on the timescale of 200 seconds was noticed, resulting in the identification of the primary star as a B-type subdwarf in 2003.[10] Under a proposed classification scheme for hot subdwarfs it would be class sdB1VII:He1. This non-standard system indicates that it is a "normal" luminosity for a hot subdwarf and that the spectrum is dominated by hydrogen rather than helium.[11]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Virgo |
| Right ascension | 13h 38m 48.14669s[2] |
| Declination | −02° 01′ 49.2073″[2] |
| Apparent magnitude (V) | 13.30 - 14.22[3] |
| Characteristics | |
| Spectral type | sdB + M5[4] |
| Variable type | EA + RPHS[3] |
| Astrometry | |
| Radial velocity (Rv) | −25.0[5] km/s |
| Proper motion (μ) | RA: −6.145±0.054 mas/yr[2] Dec.: −12.054±0.025 mas/yr[2] |
| Parallax (π) | 1.6801 ± 0.0376 mas[2] |
| Distance | 1,940 ± 40 ly (600 ± 10 pc) |
| Absolute magnitude (MV) | 4.49[6] |
| Orbit[7] | |
| Primary | NY Virginis A |
| Companion | NY Virginis B |
| Period (P) | 0.101015968166 d |
| Semi-major axis (a) | 0.0160 AU |
| Eccentricity (e) | 0.46 |
| Details | |
| NY Virginis A | |
| Mass | 0.459±0.005[6] M☉ |
| Radius | 0.151±0.001[6] R☉ |
| Luminosity | 23.3±1.5[6] L☉ |
| Surface gravity (log g) | 5.739±0.002[6] cgs |
| Temperature | 32,740±400[6] K |
| Rotation | 2.42438 hours[6] |
| NY Virginis B | |
| Mass | 0.122[8] M☉ |
| Radius | 0.16[8] R☉ |
| Surface gravity (log g) | 5.14[8] cgs |
| Temperature | 3,000[8] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
Planetary system edit
In 2011, variations in the timing of the binary star's eclipses were used to infer the presence of a superjovian planet, NY Virginis (AB) b, on a wide orbit, with a second planet being suspected.[12] A study in 2014 found that a two-planet model was preferred. The orbits of these two planets are near or at a 3:10 mutual orbital resonance.[7] Another two-planet model with significant orbital eccentricity, updated to account for changes in eclipse timing not predicted by previous models, was published in 2019.[4]
Studies in 2022 have noted that since planetary models generally fail to predict subsequent changes in eclipse timing,[13] and the most recent two-planet model as of 2021 results in orbits that are unstable on an astronomically-short timescale,[14][15] a different explanation for the eclipse timing variations may be needed.
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (controversial) | >2.7 MJ | 3.3 | 3160 | 0.15 | — | — |
| c (controversial) | >5.5 MJ | 7.54 | 9861.75 | 0.15 | — | — |
References edit
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- ^ 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.
- ^ a b 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.
- ^ a b c Song, Shuo; Mai, Xinyu; Mutel, Robert L.; Pulley, David; Faillace, George; Watkins, Americo (2019). "An Updated Model for Circumbinary Planets Orbiting the SDB Binary NY Virginis". The Astronomical Journal. 157 (5): 184. Bibcode:2019AJ....157..184S. doi:10.3847/1538-3881/ab1139.
- ^ a b "V* NY Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 September 2020.
- ^ a b c d e f g Charpinet, S.; Van Grootel, V.; Reese, D.; Fontaine, G.; Green, E. M.; Brassard, P.; Chayer, P. (2008). "Testing the forward modeling approach in asteroseismology. II. Structure and internal dynamics of the hot B subdwarf component in the close eclipsing binary system PG 1336-018". Astronomy and Astrophysics. 489 (1): 377. Bibcode:2008A&A...489..377C. doi:10.1051/0004-6361:200809907.
- ^ a b c Lee, Jae Woo; Hinse, Tobias Cornelius; Youn, Jae-Hyuck; Han, Wonyong (2014). "The Pulsating sdB+M Eclipsing System NY Virginis and its Circumbinary Planets". Monthly Notices of the Royal Astronomical Society. 445 (3): 2331–2339. arXiv:1409.4907. Bibcode:2014MNRAS.445.2331L. doi:10.1093/mnras/stu1937. S2CID 119173891.
- ^ a b c d e Vučković, M.; Aerts, C.; Østensen, R.; Nelemans, G.; Hu, H.; Jeffery, C. S.; Dhillon, V. S.; Marsh, T. R. (2007). "The binary properties of the pulsating subdwarf B eclipsing binary PG 1336-018 (NY Virginis)". Astronomy & Astrophysics. 471 (2): 605–615. arXiv:0706.3363. Bibcode:2007A&A...471..605V. doi:10.1051/0004-6361:20077179. S2CID 17812329.
- ^ Kilkenny, D.; O'Donoghue, D.; Koen, C.; Lynas-Gray, A. E.; Van Wyk, F. (1998). "The EC 14026 stars - VIII. PG 1336-018: A pulsating SDB star in an HWVir-type eclipsing binary". Monthly Notices of the Royal Astronomical Society. 296 (2): 329. Bibcode:1998MNRAS.296..329K. doi:10.1046/j.1365-8711.1998.01432.x.
- ^ Kilkenny, D.; Reed, M. D.; O'Donoghue, D.; Kawaler, S. D.; Mukadam, A.; Kleinman, S. J.; Nitta, A.; Metcalfe, T. S.; Provencal, J. L.; Watson, T. K.; Sullivan, D. J.; Sullivan, T.; Shobbrook, R.; Jiang, X. J.; Joshi, S.; Ashoka, B. N.; Seetha, S.; Leibowitz, E.; Ibbetson, P.; Mendelson, H.; Meištas, E.; Kalytis, R.; Ališauskas, D.; Martinez, P.; Van Wyk, F.; Stobie, R. S.; Marang, F.; Zola, S.; Krzesinski, J.; et al. (2003). "A Whole Earth Telescope campaign on the pulsating subdwarf B binary system PG 1336-018 (NY Vir)". Monthly Notices of the Royal Astronomical Society. 345 (3): 834. Bibcode:2003MNRAS.345..834K. doi:10.1046/j.1365-8711.2003.07007.x. hdl:10183/89981.
- ^ Drilling, J. S.; Jeffery, C. S.; Heber, U.; Moehler, S.; Napiwotzki, R. (2013). "An MK-like system of spectral classification for hot subdwarfs". Astronomy & Astrophysics. 551: A31. Bibcode:2013A&A...551A..31D. doi:10.1051/0004-6361/201219433.
- ^ a b Qian, S.-B.; Zhu, L.-Y.; Dai, Z.-B.; Fernández-Lajús, E.; Xiang, F.-Y.; He, J.-J. (2011). "Circumbinary Planets Orbiting the Rapidly Pulsating Subdwarf B-type binary NY Vir". The Astrophysical Journal. 745 (2): L23. arXiv:1112.4269. doi:10.1088/2041-8205/745/2/L23. S2CID 118745084.
- ^ Pulley, D.; Sharp, I. D.; Mallett, J.; von Harrach, S. (August 2022). "Eclipse timing variations in post-common envelope binaries: Are they a reliable indicator of circumbinary companions?". Monthly Notices of the Royal Astronomical Society. 514 (4): 5725–5738. arXiv:2206.06919. Bibcode:2022MNRAS.514.5725P. doi:10.1093/mnras/stac1676.
- ^ Er, Huseyin; Özdönmez, Aykut; Nasiroglu, Ilham (October 2021). "New observations of the eclipsing binary system NY Vir and its candidate circumbinary planets". Monthly Notices of the Royal Astronomical Society. 507 (1): 809–817. arXiv:2107.07003. Bibcode:2021MNRAS.507..809E. doi:10.1093/mnras/stab2054.
- ^ Mai, Xinyu; Mutel, Robert L. (November 2022). "Orbital stability of proposed NY Virginis exoplanets". Monthly Notices of the Royal Astronomical Society: Letters. 517 (1): L108–L110. arXiv:2210.00214. Bibcode:2022MNRAS.517L.108M. doi:10.1093/mnrasl/slac118.