Struve 2398

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Struve 2398 AB
Draco constellation map.svg
Red pog.png
Struve 2398
Location of Struve 2398 in the constellation Draco

Observation data
Epoch J2000       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  mas/yr [1]
Dec.: +1792.325  mas/yr [1]
Parallax (π)283.8401 ± 0.0220  mas [1]
Distance 11.4908 ± 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 [3]
Dec.: +1862.525  mas/yr [3]
Parallax (π)283.8378 ± 0.0287  mas [3]
Distance 11.491 ± 0.001  ly
(3.5231 ± 0.0004  pc)
Orbit [5]
CompanionStruve 2398 B
Period (P)871±108 yr
Semi-major axis (a)63±1  AU
Eccentricity (e)0.29±0.01
Inclination (i)69.8±0.4°
Longitude of the node (Ω)143.0±0.3°
Argument of periastron (ω)
(secondary)		272.2+2.9
−3.0°
Details
Struve 2398 A
Mass 0.336±0.007 [6]   M☉
Radius 0.354±0.003 [6]   R☉
Luminosity 0.01511±0.00019 [6]   L☉
Temperature 3,401+18
−17 [6]   K
Metallicity [Fe/H]−0.23±0.08 [4]   dex
Rotation 103.1±6.1  d [7]
Rotational velocity (v sin i)< 2.5 [8]  km/s
Age 3.0 [4]   Gyr
Struve 2398 B
Mass 0.248±0.025 [4]   M☉
Radius 0.273±0.011 [4]   R☉
Luminosity0.021  L☉
Temperature 3,345±60 [4]   K
Metallicity [Fe/H]−0.30±0.08 [4]   dex
Rotation 135±15  d [7]
Rotational velocity (v sin i)< 2.5 [8]  km/s
Age 2.4 [4]   Gyr
Other designations
Σ 2398, BD+59°1915, GJ  725 A/B, ADS  11632, GCTP 4330.00 A/B
Struve 2398 A: Vyssotsky 184, HD  173739, HIP  91768, G 227-046, LHS  58
Struve 2398 B: HD  173740, HIP  91772, G 227-047, LHS  59
Database references
SIMBAD The 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.

Contents

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, [9] and their active surfaces are sources of X-ray emission. [10] They are orbiting with a period of about 871 years, at a separation of about 63 astronomical units with an orbital eccentricity of 0.29. [5]

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

Struve 2398 A is known to host one planet, a likely super-Earth discovered in 2024 using the radial velocity method. This planet has a minimum mass 2.8 times that of Earth, and has a close orbit with a period of 11 days; it is too close to its star to be in the habitable zone. TESS observations show that the planet likely does not transit its host star. [5]

Struve 2398 B may also host planets. In 2016, an Earth-mass planet candidate on a 2.7-day orbit was proposed around Struve 2398 B based on radial velocity observations, although this could not be confirmed as a periodic signal. [12] A 2019 study also using radial velocity instead proposed two candidate Neptune-mass planets on longer-period orbits. [13]

The Struve 2398 A (Gliese 725 A) planetary system [5]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b≥2.78±0.35  M🜨 0.068±0.00111.2201±0.0051———
The Struve 2398 B (Gliese 725 B) planetary system [13]
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

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References

  1. 1 2 3 4 5 6 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. ↑ 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. arXiv: 1112.4567 . Bibcode:2012ApJ...748...93R. doi:10.1088/0004-637X/748/2/93. S2CID   41902340. See Table 3.
  3. 1 2 3 4 5 6 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.
  4. 1 2 3 4 5 6 7 8 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, arXiv: 1501.01635 , Bibcode:2015ApJ...804...64M, doi:10.1088/0004-637X/804/1/64, S2CID   19269312, 64.
  5. 1 2 3 4 Cortes-Zuleta, P.; Boisse, I.; et al. (November 2024). "Gl 725A b: a potential super-Earth detected with SOPHIE and SPIRou in an M dwarf binary system at 3.5 pc". Astronomy & Astrophysics . arXiv: 2411.09506 .
  6. 1 2 3 4 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. arXiv: 2106.07656 . Bibcode:2021ApJ...918...40P. doi: 10.3847/1538-4357/ac0aea . S2CID   235435757. 40.
  7. 1 2 Donati, J.-F.; Lehmann, L. T.; et al. (October 2023). "Magnetic fields and rotation periods of M dwarfs from SPIRou spectra". Monthly Notices of the Royal Astronomical Society . 525 (2): 2015–2039. arXiv: 2307.14190 . Bibcode:2023MNRAS.525.2015D. doi: 10.1093/mnras/stad2301 .
  8. 1 2 Reiners, Ansgar; et al. (April 2012), "A Catalog of Rotation and Activity in Early-M Stars", The Astronomical Journal, 143 (4): 15, arXiv: 1201.5774 , Bibcode:2012AJ....143...93R, doi:10.1088/0004-6256/143/4/93, S2CID   118425326, 93.
  9. ↑ Pettersen, B. R. (1991), "The nearby flare stars", Società Astronomica Italiana, Memorie, 62: 217–242, Bibcode:1991MmSAI..62..217P.
  10. ↑ 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. Bibcode:1995ApJ...450..392S. doi: 10.1086/176149 .
  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, arXiv: 1604.05312 , Bibcode:2016MNRAS.459.3551B, doi: 10.1093/mnras/stw906
  13. 1 2 Barnes, J. R.; et al. (2019-06-11), Frequency of planets orbiting M dwarfs in the Solar neighbourhood, arXiv: 1906.04644v1
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