Struve 2398 (Gliese 725) is a binary star system in the northern constellation of

Draco Draco is the Latin word for serpent or dragon. Draco or Drako may also refer to: People * Draco (lawgiver) (from Greek: Δράκων; 7th century BC), the first lawgiver of ancient Athens, Greece, from whom the term ''draconian'' is derived * ...

. Struve 2398 is star number 2398 in the Struve Double Star Catalog of Baltic-German astronomer

Friedrich Georg Wilhelm von Struve Friedrich Georg Wilhelm von Struve (russian: link=no, Василий Яковлевич Струве, trans. ''Vasily Yakovlevich Struve''; 15 April 1793 – ) was a Baltic German astronomer and geodesist from the famous Struve family. He is be ...

. 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 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 star A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in th ...

s, and their active surfaces are sources of X-ray emission. They are orbiting with period of about 295 years, at a separation of about 56

astronomical units The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits ...

with an orbital eccentricity (ovalness) of 0.70. 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 The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...

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 Galactic Center or Galactic Centre is the rotational center, the barycenter, of the Milky Way galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a compact ra ...

. The plane of their galactic orbit carries them as far as 463−489 pc away from the

galactic plane The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms ''galactic plane'' and ''galactic poles'' usual ...

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. In 2019, two candidate planets were detected in orbit around component B using the

radial velocity method Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in t ...

, without detection of the previous candidate.

References

External links

SolStation entry
* http://www.daviddarling.info/encyclopedia/S/Struve2398.html * http://www.richweb.f9.co.uk/astro/nearby_stars.htm * http://jumk.de/astronomie/near-stars/struve-2398.shtml

{{DEFAULTSORT:Struve 2398 173739 40 091768 72 0725 BD+59 1915 Draco (constellation) Local Bubble M-type main-sequence stars Binary stars Flare stars Hypothetical planetary systems

Planetary system

See also

References

External links