Astronomy:NY Virginis

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Short description: Binary star in the constellation Virgo
NY Virginis
NYVirLightCurve.png
A light curve for NY Virginis, plotted from TESS data[1]
Observation data
Equinox J2000.0]] (ICRS)
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[2] mas/yr
Dec.: −12.054±0.025[2] mas/yr
Parallax (π)1.6801 ± 0.0376[2] mas
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
NY Virginis A
Mass0.459±0.005[6] M☉
Radius0.151±0.001[6] R☉
Luminosity23.3±1.5[6] L☉
Surface gravity (log g)5.739±0.002[6] cgs
Temperature32,740±400[6] K
Rotation2.42438 hours[6]
NY Virginis B
Mass0.122[8] M☉
Radius0.16[8] R☉
Surface gravity (log g)5.14[8] cgs
Temperature3,000[8] 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.[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]

Planetary system

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.

The NY Virginis planetary system[12][7][4]
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

  1. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  2. ↑ 2.0 2.1 2.2 2.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 Samus, N. N. 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. ↑ 4.0 4.1 4.2 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. doi:10.3847/1538-3881/ab1139. Bibcode: 2019AJ....157..184S. 
  5. ↑ 5.0 5.1 "V* NY Vir". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V%2A+NY+Vir. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 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. doi:10.1051/0004-6361:200809907. Bibcode: 2008A&A...489..377C. 
  7. ↑ 7.0 7.1 7.2 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. doi:10.1093/mnras/stu1937. Bibcode: 2014MNRAS.445.2331L. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 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. doi:10.1051/0004-6361:20077179. Bibcode: 2007A&A...471..605V. 
  9. ↑ 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. doi:10.1046/j.1365-8711.1998.01432.x. Bibcode: 1998MNRAS.296..329K. 
  10. ↑ Kilkenny, D.; Reed, M. D.; O'Donoghue, D.; Kawaler, S. D.; Mukadam, A.; Kleinman, S. J.; Nitta, A.; Metcalfe, T. S. 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. doi:10.1046/j.1365-8711.2003.07007.x. Bibcode: 2003MNRAS.345..834K. 
  11. ↑ 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. doi:10.1051/0004-6361/201219433. Bibcode: 2013A&A...551A..31D. 
  12. ↑ 12.0 12.1 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. doi:10.1088/2041-8205/745/2/L23. 
  13. ↑ 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. doi:10.1093/mnras/stac1676. Bibcode: 2022MNRAS.514.5725P. 
  14. ↑ 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. doi:10.1093/mnras/stab2054. Bibcode: 2021MNRAS.507..809E. 
  15. ↑ 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. doi:10.1093/mnrasl/slac118. Bibcode: 2022MNRAS.517L.108M. 

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



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