NN Serpentis

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NN Serpentis A/B
NN Serpentis binary.png

Rendering of NN Serpentis system
Observation data
Epoch {{{epoch}}}      Equinox
Constellation Serpens
Right ascension 15h 52m 56.2s
Declination +12° 54′ 47.2″
Apparent magnitude (V) +16.6
Spectral type DAO1 / M4V
Mass 0.535/0.111 [1] M
Radius 0.0211/0.154 [1] R
Luminosity 4.2/0.00172? [1] L
Temperature 57000/3000? [1] K
Period (P) 0.000356[1] yr
Semi-major axis (a) 0.00397884 AU[1]"
Eccentricity (e) 0.0
Inclination (i) 89.6[1]°
Other designations
NN Serpentis, NN Ser, PG 1550+131, WD 1550+130
Database references

NN Serpentis (abbreviated NN Ser) is an eclipsing post-common envelope binary system approximately 1670 light-years away[1]. The system comprises an eclipsing white dwarf and red dwarf. The two stars orbit each other every 0.13 days.[1]

Planetary system[edit]

A planetary systems 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 we 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.

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.[2]

In late 2009, Qian [3] 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. This has since been disproven by further measurements of the eclipse times of the binary stars.[4]

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).[5] 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.

The NN Serpentis planetary system[6]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
c 6.91 ± 0.54 MJ 5.38 ± 0.2 5660 ± 165 days 0
b 2.28 ± 0.38 MJ 3.39 ± 0.1 AU 2830 ± 130 days 0.2 ± 0.02

See also[edit]


  1. ^ a b c d e f g h i Parsons; et al. (2009). "Precise mass and radius values for the white dwarf and low mass M dwarf in the pre-cataclysmic binary NN Serpentis". arXiv:0909.4307. 
  2. ^ Chen (2009). "Can angular momentum loss cause the period change of NN Ser?". arXiv:0904.2319. Bibcode:2009A&A...499L...1C. doi:10.1051/0004-6361/200911638. 
  4. ^ Parsons; et al. (2010). "Orbital Period Variations in Eclipsing Post Common Envelope Binaries". arXiv:1005.3958. 
  5. ^ http://www.aanda.org/index.php?option=com_article&access=standard&Itemid=129&url=/articles/aa/abs/2010/13/aa15472-10/aa15472-10.html
  6. ^ Schneider, J. "Notes for star NN Ser". The Extrasolar Planets Encyclopaedia. Retrieved 2010-10-22. 

External links[edit]

Coordinates: Sky map 12h 44m 20.2367s, −08° 40′ 16.837″