Struve 2398 information

Struve 2398 AB
	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
Declination	+59° 37′ 49.4095″
Apparent magnitude (V)	8.94
	Struve 2398 B
Right ascension	18h 42m 46.89467s
Declination	+59° 37′ 36.7212″
Apparent magnitude (V)	9.70
Characteristics
Spectral type	M3 V + M3.5 V
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 km/s
Proper motion (μ)	RA: –1311.679 mas/yr ; Dec.: +1792.325 mas/yr
Parallax (π)	283.8401 ± 0.0220 mas
Distance	11.4908 ± 0.0009 ly ; (3.5231 ± 0.0003 pc)
Struve 2398 B
Radial velocity (Rv)	0.88±0.15 km/s
Proper motion (μ)	RA: –1400.264 mas/yr ; Dec.: +1862.525 mas/yr
Parallax (π)	283.8378 ± 0.0287 mas
Distance	11.491 ± 0.001 ly ; (3.5231 ± 0.0004 pc)
Details
Struve 2398 A
Mass	0.336±0.007 M☉
Radius	0.354±0.003 R☉
Luminosity	0.01511±0.00019 L☉
Temperature	3,401+18; −17 K
Metallicity [Fe/H]	−0.23±0.08 dex
Rotational velocity (v sin i)	< 2.5 km/s
Age	3.0 Gyr
Struve 2398 B
Mass	0.248±0.025 M☉
Radius	0.273±0.011 R☉
Luminosity	0.021 L☉
Temperature	3,345±60 K
Metallicity [Fe/H]	−0.30±0.08 dex
Rotational velocity (v sin i)	< 2.5 km/s
Age	2.4 Gyr
Orbit
Companion	Struve 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.

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]

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^ ^a ^b ^c ^d Cite error: The named reference Pineda2021 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference aj143_4_93 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference aaass26 was invoked but never defined (see the help page).
^ Cite error: The named reference pettersen1991 was invoked but never defined (see the help page).
^ Cite error: The named reference Schmitt was invoked but never defined (see the help page).
^ "Struve 2398 AB". Retrieved 2010-10-22.
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[Gaia3a-1] Cite error: The named reference Gaia3a was invoked but never defined (see the help page).

[apj748_2_934-2] Cite error: The named reference apj748_2_934 was invoked but never defined (see the help page).

[Gaia3b-3] Cite error: The named reference Gaia3b was invoked but never defined (see the help page).

[apj804_1_64-4] ^ ^a ^b ^c ^d ^e ^f ^g ^h Cite error: The named reference apj804_1_64 was invoked but never defined (see the help page).

[Pineda2021-5] Cite error: The named reference Pineda2021 was invoked but never defined (see the help page).

[aj143_4_93-6] Cite error: The named reference aj143_4_93 was invoked but never defined (see the help page).

[aaass26-7] Cite error: The named reference aaass26 was invoked but never defined (see the help page).

[pettersen1991-8] Cite error: The named reference pettersen1991 was invoked but never defined (see the help page).

[Schmitt-9] Cite error: The named reference Schmitt was invoked but never defined (see the help page).

[SolStation-10] "Struve 2398 AB". Retrieved 2010-10-22.

[rmaa34_37-11] Cite error: The named reference rmaa34_37 was invoked but never defined (see the help page).

Observation data Epoch J2000 Equinox J2000
Struve 2398 Location of Struve 2398 in the constellation Draco
Constellation	Draco
Struve 2398 A
Right ascension	18^h 42^m 46.70439^s^[1]
Declination	+59° 37′ 49.4095″^[1]
Apparent magnitude (V)	8.94^[2]
Struve 2398 B
Right ascension	18^h 42^m 46.89467^s^[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 (R_v)	−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 (R_v)	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`_☉
Luminosity	0.021 `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]
Companion	Struve 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 information

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