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NY Virginis

Coordinates: Sky map 13h 38m 48.1466s, −02° 01′ 49.2095″
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NY Virginis

A light curve for NY Virginis, plotted from TESS data[1]
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]
Distance1,940 ± 40 ly
(600 ± 10 pc)
Absolute magnitude (MV)4.49[6]
Orbit[7]
PrimaryNY Virginis A
CompanionNY Virginis B
Period (P)0.101015968166 d
Semi-major axis (a)0.0160 AU
Eccentricity (e)0.46
Details[8]
NY Virginis A
Mass0.471±0.006 M☉
Radius0.1474±0.0009 R☉
Luminosity23.3±1.5[6] L☉
Surface gravity (log g)5.76 cgs
Temperature32,850±175 K
Rotation2.42438 hours[6]
NY Virginis B
Mass0.13 M☉
Radius0.155 R☉
Surface gravity (log g)5.16 cgs
Temperature3,000[9] K
Other designations
Gaia DR2 3637481302758519040, GSC 04966-00491, 2MASS J13384814-0201491, PG 1336−018[5]
Database references
SIMBADdata

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.[9] The binary nature of NY Virginis was first identified in 1998,[10] 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.[11] 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.[12]

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.[13] 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,[14] and the most recent two-planet model as of 2021 results in orbits that are unstable on an astronomically-short timescale.[15][16]

However, in 2023 another model with circular orbits was proposed, which gives stability to the system. The same team also find that it is valid that there are exoplanets in the system creating the eclipe timing variations, and that the moderate eccentricites of the previous model likely caused the orbital instability.[8]

The NY Virginis planetary system[8]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b >2.164+0.100
−0.099 MJ 		>3.540+0.038
−0.036 		3140+50
−48 		0 — —
c >3.939+0.159
−0.113 MJ 		>6.52+0.22
−0.18 		8309+398
−326 		0 — —

References

[edit]
  1. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  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 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 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. arXiv:1812.01726. Bibcode:2019AJ....157..184S. doi:10.3847/1538-3881/ab1139.
  5. ^ a b "V* NY Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 September 2020.
  6. ^ a b c 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.
  7. ^ a b 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.
  8. ^ a b c Esmer, Ekrem Murat; Baştürk, Özgür; Selam, Selim Osman (2023-09-05). "Testing the planetary hypothesis of NY Virginis: anticipated change in the eclipse timing trend within the next five years". Monthly Notices of the Royal Astronomical Society. 525 (4): 6050–6063. doi:10.1093/mnras/stad2648. ISSN 0035-8711.
  9. ^ a b 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.
  10. ^ 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.
  11. ^ 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.
  12. ^ 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.
  13. ^ 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. Bibcode:2012ApJ...745L..23Q. doi:10.1088/2041-8205/745/2/L23. S2CID 118745084.
  14. ^ 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.
  15. ^ 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.
  16. ^ 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.


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