NY Virginis

NY Virginis is a binary star about 1,800 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.[7] The binary nature of NY Virginis was first identified in 1998,[8]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.[9] 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.[10]

NY Virginis

Observation data Epoch J2000      Equinox J2000
Constellation	Virgo
Right ascension	13^h 38^m 48.1466^s[1]
Declination	−02° 01′ 49.2095″[1]
Apparent magnitude (V)	13.30 - 14.22[2]
Characteristics
Spectral type	sdB + M5[3]
Variable type	EA + RPHS[2]
Astrometry
Radial velocity (Rv)	−25.0[4] km/s
Proper motion (μ)	RA: −6.112[4] mas/yr Dec.: −11.914[4] mas/yr
Parallax (π)	1.8116 ± 0.0632[4] mas
Distance	1,800 ± 60 ly (550 ± 20 pc)
Absolute magnitude (MV)	4.49[5]
Orbit[6]
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[5] M☉
Radius	0.151±0.001[5] R☉
Luminosity	23.3±1.5[5] L☉
Surface gravity (log g)	5.739±0.002[5] cgs
Temperature	32,740±400[5] K
Rotation	2.42438 hours[5]
NY Virginis B
Mass	0.122[7] M☉
Radius	0.16[7] R☉
Surface gravity (log g)	5.14[7] cgs
Temperature	3,000[7] K
Other designations
Gaia DR2 3637481302758519040, GSC 04966-00491, 2MASS J13384814-0201491, PG 1336−018[1]
Database references
SIMBAD	data

Planetary system

In 2011 one superjovian planet NY Virginis (AB) b on a wide orbit was discovered utilising the eclipse timing method, and one more was marked as suspected.[11] The second planet, NY Virginis (AB) c, was confirmed in 2014. Orbits of these two planets are near or at a 3:10 mutual orbital resonance.[6] The planetary system parameters were updated in 2019, because significant eccentricity of the orbits was detected.[3]

The NY Virginis planetary system[11][6][3]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
NY Virginis (AB) b	>2.7 MJ	3.3	3160	0.15	—	—
NY Virginis (AB) c	>5.5 MJ	7.54	9861.75	0.15	—	—

References

1. "V* NY Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 September 2020.
2. 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.
3. 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.
4. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
5. 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.
6. 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.
7. 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. Bibcode:2007A&A...471..605V. doi:10.1051/0004-6361:20077179. S2CID 17812329.
8. 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.
9. 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.
10. 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.
11. 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.