NN Serpentis

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NN Serpentis
NN Serpentis binary.png

Rendering of NN Serpentis system
Observation data
Epoch J2000        Equinox J2000
Constellation Serpens
Right ascension 15h 52m 56.12035s [1]
Declination +12° 54′ 44.4293″ [1]
Apparent magnitude  (V)+16.51 [2]
Characteristics
Spectral type WD DAO1 / M4V [3]
Astrometry
Proper motion (μ)RA: −30.170±0.055 mas/yr [1]
Dec.: −59.084±0.057 mas/yr [1]
Parallax (π)1.9438±0.0662  mas [1]
Distance 1,680 ± 60  ly
(510 ± 20  pc)
Orbit [3]
Period (P)0.13008017141(17) d
Semi-major axis (a)0.934 ± 0.009 R☉
Eccentricity (e)0.0
Inclination (i)89.6 ± 0.2°
Semi-amplitude (K1)
(primary)		62.3 ± 1.9 km/s
Semi-amplitude (K2)
(secondary)		301 ± 3 km/s
Details [3]
White dwarf
Mass 0.535 ± 0.012  M☉
Radius 0.0211 ± 0.0002  R☉
Surface gravity (log g)7.47 ± 0.01  cgs
Temperature 57000 ± 3000  K
Red dwarf
Mass 0.111 ± 0.004  M☉
Radius 0.149 ± 0.002  R☉
Other designations
NN Ser, PG 1550+131, WD 1550+130
Database references
SIMBAD data

NN Serpentis (abbreviated NN Ser) is an eclipsing post-common envelope binary system approximately 1670 light-years away. [3] The system comprises an eclipsing white dwarf and red dwarf. The two stars orbit each other every 0.13 days. [3]

Contents

In 1982, Richard F. Green et al. found the star in the Palomar Green Survey, and determined it to be a possible cataclysmic variable star. They gave it the name PG 1550+131. [4] Photometric observations by John W. Wilson et al. in 1983 showed that PG 1550+131 was indeed a variable star. [5] Reinhold Haefner discovered that the star is an eclipsing binary, in 1988. [6] It was given its variable star designation, NN Serpentis, in 1989. [7]

Planetary system

A planetary system has been inferred to exist around NN Ser by several teams. All of these teams rely on the fact that Earth sits in the same plane as the NN Serpentis binary star system, so humans can see the larger red dwarf eclipse the white dwarf every 0.13 days. Astronomers are then able to use these frequent eclipses to spot a pattern of small but significant irregularities in the orbit of stars, which could be attributed to the presence and gravitational influence of circumbinary planets.

A green light light curve for NN Serpentis, adapted from Parsons et al. (2010) NNSerLightCurve.png
A green light light curve for NN Serpentis, adapted from Parsons et al. (2010)

Chen (2009) used these "eclipse timing variations" to suggesting a putative orbital period spanning between 30 and 285 years and a minimum mass between 0.0043 and 0.18 Solar masses. [9]

In late 2009, Qian estimated a minimum mass of 10.7 Jupiter masses and orbital period of 7.56 years for this planet, probably located at 3.29 Astronomical Units. [10] This has since been disproven by further measurements of the eclipse times of the binary stars. [8]

In late 2009 and 2010, researchers from the UK (University of Warwick and the University of Sheffield), Germany (Georg-August-Universitat in Göttingen, Eberhard-Karls-Universitat in Tübingen), Chile (Universidad de Valparaíso), and the United States (University of Texas at Austin) suggested that the eclipse timing variations are caused by two gas giant planets. The more massive gas giant is about 6 times the mass of Jupiter and orbits the binary star every 15.5 years, the other orbits every 7.75 years and is about 1.6 times the mass of Jupiter. [11]

All published planetary models have failed to predict changes in eclipse timing since 2018, suggesting that a different explanation for the eclipse timing variations may be needed. [12]

The NN Serpentis planetary system [13]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
d(controversial)2.28 ± 0.38 MJ 3.39 ± 0.12830 ± 1300.2 ± 0.02——
c(controversial)6.91 ± 0.54 MJ 5.38 ± 0.25660 ± 1650——

See also

References

  1. 1 2 3 4 5 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.
  2. ↑ Drake, A. J.; Graham, M. J.; Djorgovski, S. G.; Catelan, M.; Mahabal, A. A.; Torrealba, G.; García-Álvarez, D.; Donalek, C.; Prieto, J. L.; Williams, R.; Larson, S.; Christen Sen, E.; Belokurov, V.; Koposov, S. E.; Beshore, E.; Boattini, A.; Gibbs, A.; Hill, R.; Kowalski, R.; Johnson, J.; Shelly, F. (2014). "The Catalina Surveys Periodic Variable Star Catalog". The Astrophysical Journal Supplement Series. 213 (1): 9. arXiv: 1405.4290 . Bibcode:2014ApJS..213....9D. doi:10.1088/0067-0049/213/1/9. S2CID   119180446.
  3. 1 2 3 4 5 Parsons, S. G.; Marsh, T. R.; Copperwheat, C. M.; Dhillon, V. S.; Littlefair, S. P.; Gänsicke, B. T.; Hickman, R. (2010). "Precise mass and radius values for the white dwarf and low mass M dwarf in the pre-cataclysmic binary NN Serpentis". Monthly Notices of the Royal Astronomical Society. 402 (4): 2591–2608. arXiv: 0909.4307 . Bibcode:2010MNRAS.402.2591P. doi: 10.1111/j.1365-2966.2009.16072.x . S2CID   15186725.
  4. ↑ Green, R. F.; Ferguson, D. H.; Liebert, J.; Schmidt, M. (June 1982). "Cataclysmic variable candidates from the Palomar Green Survey". Publications of the Astronomical Society of the Pacific. 94: 560–564. Bibcode:1982PASP...94..560G. doi:10.1086/131022 . Retrieved 12 September 2025.
  5. ↑ Wilson, J. W.; Miller, H. R.; Africano, J. L.; Goodrich, B. D.; Mahaffey, C. T.; Quigley, R. J. (December 1986). "Photoelectric photometry of six cataclysmic variable stars". Astronomy and Astrophysics, Suppl. Ser. 66: 323–330. Bibcode:1986A&AS...66..323W . Retrieved 12 September 2025.
  6. ↑ Haefner, R. (March 1989). "The spectacular binary system PG 1550+131". The Messenger. 55: 61–62. Bibcode:1989Msngr..55...61H . Retrieved 12 September 2025.
  7. ↑ Kholopov, P. N.; Samus, N. N.; Kazarovets, B. V.; Frolov, M. S.; Kireeva, N. N. (April 1989). "The 69th Name-List of Variable Stars". Information Bulletin on Variable Stars. 3323: 1–20. Bibcode:1989IBVS.3323....1K . Retrieved 12 September 2025.
  8. 1 2 Parsons; et al. (2010). "Orbital Period Variations in Eclipsing Post Common Envelope Binaries". Monthly Notices of the Royal Astronomical Society. 407 (4): 2362–2382. arXiv: 1005.3958 . Bibcode:2010MNRAS.407.2362P. doi: 10.1111/j.1365-2966.2010.17063.x . S2CID   96441672.
  9. ↑ Chen (2009). "Can angular momentum loss cause the period change of NN Ser?". Astronomy and Astrophysics. 499 (1): L1 –L3. arXiv: 0904.2319 . Bibcode:2009A&A...499L...1C. doi:10.1051/0004-6361/200911638. S2CID   15999559.
  10. ↑ Qian, S. B.; Dai, Z. B.; Liao, W. P.; Zhu, L. Y.; Liu, L.; Zhao, E. G. (November 2009). "A Substellar Companion to the White Dwarf-Red Dwarf Eclipsing Binary NN Ser". The Astrophysical Journal Letters. 706 (1): L96 –L99. Bibcode:2009ApJ...706L..96Q. doi:10.1088/0004-637X/706/1/L96 . Retrieved 12 September 2025.
  11. ↑ K. Beuermann; et al. (October 2010). "Two planets orbiting the recently formed post-common envelope binary NN Serpentis". Astronomy & Astrophysics. 521: L60. arXiv: 1010.3608 . Bibcode:2010A&A...521L..60B. doi:10.1051/0004-6361/201015472. S2CID   53702506.
  12. ↑ 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 .
  13. ↑ Schneider, J. "Notes for star NN Ser". Extrasolar Planets Encyclopaedia . Archived from the original on 2010-10-15. Retrieved 2010-10-22.
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