GJ 1245

V1581 Cygni

A blue band light curve for a flare of V1581 Cygni. The left-most point shows a 1 sigma error bar. Adapted from Cristaldi and Rodonò (1976)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
GJ 1245 AC
Right ascension 19h 53m 55.142s[2]
Declination +44° 24′ 44.39″[2]
Apparent magnitude (V) 13.46 / 16.75[3]
GJ 1245 B
Right ascension 19h 53m 55.141s[4]
Declination +44° 24′ 54.15″[4]
Apparent magnitude (V) 14.01[3]
Characteristics
Spectral type M6V / M8V[5] / M6V[6]
Variable type UV Cet[7]
Astrometry
Radial velocity (Rv)3.93±0.38[4] km/s
Proper motion (μ) RA: 349.363(56) mas/yr[4]
Dec.: −480.322(54) mas/yr[4]
Parallax (π)214.5745 ± 0.0476 mas[4]
Distance15.200 ± 0.003 ly
(4.660 ± 0.001 pc)
Absolute magnitude (MV)15.12 / 18.41[5] / 15.72[3]
Orbit[8]
PrimaryGJ 1245 A
CompanionGJ 1245 C
Period (P)6147±17 d
Semi-major axis (a)0.8267±0.0008″
Eccentricity (e)0.334±0.002
Inclination (i)135.7±0.1°
Longitude of the node (Ω)261.2±0.2°
Periastron epoch (T)51506.8±2.1
Argument of periastron (ω)
(secondary)		36.1±0.2°
Details
GJ 1245 A
Mass0.120±0.001[5] M☉
Radius0.146±0.007[5] R☉
Luminosity0.0014[5] L☉
Temperature2,927[5] K
Metallicity [Fe/H]-0.07[5] dex
Age~300[citation needed] Myr
GJ 1245 C
Mass0.081±0.001[5] M☉
Radius0.087±0.004[5] R☉
Luminosity0.0003[5] L☉
Temperature2,611[5] K
Metallicity [Fe/H]-0.08[5] dex
Other designations
V1581 Cyg, GJ 1245, WDS J19539+4425
GJ 1245 AC: G 208-44, LHS 3494, NLTT 48414, KIC 8451868, 2MASS J19535443+4424541[9]
GJ 1245 B: G 208-45, LHS 3495, NLTT 48415, KIC 8451881, 2MASS J19535508+4424550[6]
Database references
SIMBADThe system
A
C
B
GJ 1245 is located in the constellation Cygnus.
GJ 1245 is located in the constellation Cygnus.
GJ 1245
Location of GJ 1245 in the constellation Cygnus

GJ 1245 (Gliese 1245) is a double star with components G 208-44 and G 208-45, located 15.2 light-years (4.7 parsecs) away in the constellation Cygnus. G 208-44 is itself a closer double star made up of two red dwarfs, while G 208-45 is also a red dwarf. GJ 1245 is the 43rd closest stellar system to the Solar System.[10] GJ 1245 A and B are active flare stars,[11] and the pair are collectively designated V1581 Cygni.[12]

The largest of the three stars, GJ 1245 A (G 208-44 A) is only 12% the Sun's mass.[5] Of the other two stars, GJ 1245 C (G 208-44 B), is closest to star A at 2 AU away;[13] it is 8% of the Sun's mass.[5] The third star, GJ 1245 B (G 208-45), is 27 AU away from star A,[13] and is 10% of the Sun's mass; it would appear as bright as Venus does from Earth when viewed from star A.[citation needed]

  1. ^ Cite error: The named reference Cristaldi was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference GaiaDR3A was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference RECONS was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference GaiaDR3B was invoked but never defined (see the help page).
  5. ^ a b c d e f g h i j k l m n Cite error: The named reference Dieterich2021 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference SIMBAD2 was invoked but never defined (see the help page).
  7. ^ 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. Bibcode:2009yCat....102025S.
  8. ^ Cite error: The named reference Benedict2016 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD1 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Reylé2021 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Lurie2015 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference ibvs was invoked but never defined (see the help page).
  13. ^ a b Cite error: The named reference Salama2021 was invoked but never defined (see the help page).