Struve 2398

Last updated
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)
Details
Struve 2398 A
Mass 0.336±0.007 [5]   M
Radius 0.354±0.003 [5]   R
Luminosity 0.01511±0.00019 [5]   L
Temperature 3,401+18
−17
[5]   K
Metallicity [Fe/H]−0.23±0.08 [4]   dex
Rotational velocity (v sin i)< 2.5 [6]  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
Rotational velocity (v sin i)< 2.5 [6]  km/s
Age 2.4 [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: Vyssotsky 184, HD  173739, HIP  91768, G 227-046, LHS  58
Struve 2398 B: HD  173740, G 227-047
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, [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

Related Research Articles

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References

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  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.
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  10. "Struve 2398 AB" . Retrieved 2010-10-22.
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