Astronomy:Struve 2398

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Short description: Binary star system in the constellation Draco

Coordinates: Sky map 18h 42m 46.67934s, +59° 37′ 49.4724″

Struve 2398 AB
Struve 2398 is located in the constellation Draco.
Struve 2398 is located in the constellation Draco.
Struve 2398
Location of Struve 2398 in the constellation Draco

Observation data
{{#ifeq:J2000|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| Epoch J2000      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000}}
Constellation Draco
Struve 2398 A
Right ascension  18h 42m 46.70439s[1]
Declination +59° 37′ 49.4095″[1]
Apparent magnitude (V) 8.94[2]
Struve 2398 B
Right ascension  18h 42m 46.89467s[3]
Declination +59° 37′ 36.7212″[3]
Apparent magnitude (V) 9.70
Characteristics
Spectral type M3 V + M3.5 V[4]
U−B color index 1.11/1.14
B−V color index 1.53/1.59
Variable type Flare star
Astrometry
Struve 2398 A
Radial velocity (Rv)−1.30±0.12[1] km/s
Proper motion (μ) RA: –1311.679[1] mas/yr
Dec.: +1792.325[1] mas/yr
Parallax (π)283.8401 ± 0.0220[1] mas
Distance11.4908 ± 0.0009 ly
(3.5231 ± 0.0003 pc)
Struve 2398 B
Radial velocity (Rv)0.88±0.15[3] km/s
Proper motion (μ) RA: –1400.264 mas/yr
Dec.: +1862.525 mas/yr
Parallax (π)283.8378 ± 0.0287[3] mas
Distance11.491 ± 0.001 ly
(3.5231 ± 0.0004 pc)
Details
Struve 2398 A
Mass0.336±0.007[5] M☉
Radius0.354±0.003[5] R☉
Luminosity0.01511±0.00019[5] L☉
Temperature3,401+18
−17[5] K
Metallicity [Fe/H]−0.23±0.08[4] dex
Rotational velocity (v sin i)< 2.5[6] km/s
Age3.0[4] Gyr
Struve 2398 B
Mass0.248±0.025[4] M☉
Radius0.273±0.011[4] R☉
Luminosity0.021 L☉
Temperature3,345±60[4] K
Metallicity [Fe/H]−0.30±0.08[4] dex
Rotational velocity (v sin i)< 2.5[6] km/s
Age2.4[4] Gyr
Orbit[7]
CompanionStruve 2398 B
Period (P)294.7 yr
Semi-major axis (a)10.50″
Eccentricity (e)0.70
Inclination (i)52.5°
Longitude of the node (Ω)139.9°
Periastron epoch (T)1778.0
Argument of periastron (ω)
(secondary)		203.8°
Other designations
Σ 2398, BD+59°1915, GJ 725 A/B, ADS 11632, GCTP 4330.00 A/B
Struve 2398 A: {{{names1}}}
Struve 2398 B: {{{names2}}}
Database references
SIMBADThe system
A
B

Struve 2398 (Gliese 725) is a binary star system in the northern constellation of Draco. Struve 2398 is star number 2398 in the Struve Double Star Catalog of Russian-German astronomer Friedrich Georg Wilhelm von Struve. The astronomer's surname, and hence the star identifier, is sometimes indicated by a Greek sigma, Σ; hence, this system can be listed with the identifier Σ 2398. Although the components are too faint to be viewed with the naked eye, this star system is among the closest to the Sun. Parallax measurements by the Gaia spacecraft give them an estimated distance of 11.5 light-years (3.5 parsecs) away.

Both stars are small red dwarfs, with each having around a third the Sun's mass and radius. They each display the type of variability common to flare stars,[8] and their active surfaces are sources of X-ray emission.[9] They are orbiting with period of about 295 years, at a separation of about 56 astronomical units[10] with an orbital eccentricity (ovalness) of 0.70.[7]

The pair has a relatively high proper motion of 2.2 arc seconds per year. The system is on an orbit through the Milky Way that has an eccentricity of 0.05, carrying them as close as 8 kpc and as far as 9 kpc from the Galactic Center. The plane of their galactic orbit carries them as far as 463−489 pc away from the galactic plane.[11]

Planetary system

In 2016, a planet candidate on a 2.7-day orbit was proposed around Struve 2398 B, although the signal was found to be comparable with an instrumental noise floor.[12] In 2019, two candidate planets were detected in orbit around component B using the radial velocity method, without detection of the previous candidate.[13]

The Struve 2398 B (Gliese 725 B) planetary system
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b (unconfirmed) ≥15.7±5.7 M⊕ 0.261+0.022
−0.028 		91.29+0.31
−0.24 		0.06+0.26
−0.06 		— —
c (unconfirmed) ≥13.1+8.1
−6.4 M⊕ 		0.428+0.037
−0.045 		192.4+2.2
−1.9 		0.03+0.22
−0.03 		— —

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 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.
  2. ↑ Rojas-Ayala, Bárbara et al. (April 2012). "Metallicity and Temperature Indicators in M Dwarf K-band Spectra: Testing New and Updated Calibrations with Observations of 133 Solar Neighborhood M Dwarfs". The Astrophysical Journal 748 (2): 93. doi:10.1088/0004-637X/748/2/93. Bibcode: 2012ApJ...748...93R.  See Table 3.
  3. ↑ 3.0 3.1 3.2 3.3 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.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Mann, Andrew W. et al. (May 2015), "How to Constrain Your M Dwarf: Measuring Effective Temperature, Bolometric Luminosity, Mass, and Radius", The Astrophysical Journal 804 (1): 38, doi:10.1088/0004-637X/804/1/64, 64, Bibcode: 2015ApJ...804...64M. 
  5. ↑ 5.0 5.1 5.2 5.3 Pineda, J. Sebastian; Youngblood, Allison; France, Kevin (September 2021). "The M-dwarf Ultraviolet Spectroscopic Sample. I. Determining Stellar Parameters for Field Stars". The Astrophysical Journal 918 (1): 23. doi:10.3847/1538-4357/ac0aea. 40. Bibcode: 2021ApJ...918...40P. 
  6. ↑ 6.0 6.1 Reiners, Ansgar et al. (April 2012), "A Catalog of Rotation and Activity in Early-M Stars", The Astronomical Journal 143 (4): 15, doi:10.1088/0004-6256/143/4/93, 93, Bibcode: 2012AJ....143...93R. 
  7. ↑ 7.0 7.1 Baize, P. (October 1976). "Orbital elements of eighteen visual double stars". Astronomy and Astrophysics Supplement Series 26: 177–193. Bibcode: 1976A&AS...26..177B.  Listed as ADS 11632.
  8. ↑ Pettersen, B. R. (1991), "The nearby flare stars", Società Astronomica Italiana, Memorie 62: 217–242, Bibcode: 1991MmSAI..62..217P. 
  9. ↑ Schmitt, J. H. M. M.; Fleming, T. A.; Giampapa, M. S. (September 1995). "The X-ray view of the low-mass stars in the solar neighborhood". The Astrophysical Journal 450 (9): 392–400. doi:10.1086/176149. Bibcode: 1995ApJ...450..392S. 
  10. ↑ "Struve 2398 AB". http://www.solstation.com/stars/st2398ab.htm. 
  11. ↑ Allen, C.; Herrera, M. A. (1998), "The galactic orbits of nearby UV Ceti stars", Revista Mexicana de Astronomía y Astrofísica 34: 37–46, Bibcode: 1998RMxAA..34...37A. 
  12. ↑ Berdiñas, Z. M.; Amado, P. J.; Anglada-Escudé, G.; Rodríguez-López, C.; Barnes, J. (2016), "High-cadence spectroscopy of M dwarfs – I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B", Monthly Notices of the Royal Astronomical Society 459 (4): 3551–3564, doi:10.1093/mnras/stw906 
  13. ↑ Barnes, J. R. et al. (2019-06-11) (in en), Frequency of planets orbiting M dwarfs in the Solar neighbourhood 

External links



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