Epsilon Indi

Database links to Epsilon Indi

Double star Epsilon Indi
Observation dates equinox :  J2000.0 , epoch : J2000.0
AladinLite
Constellation	Indus
Known exoplanets	1
Astrometry
Radial velocity	−40.4 km / s
parallax	(274.80 ± 0.25) (275.79 ± 0.69) mas
distance	(11.86 ± 0.01) (11.82 ± 0.03) Lj ((3.64 ± 0.01) (3.63 ± 0.01) pc )
Proper movement :
Rec. Share:	(+3967.04 ± 0.38) (4157 ± 41) mas / a
Dec. portion:	(−2535.76 ± 0.42) (−2478 ± 25) mas / a
Individual data
Names	A ; B / C
Observation data:
Right ascension	A.	22 h 03 m 21,654 s
	B / C	22 h 04 m 10.52 s
declination	A.	−56 ° 47 ′ 09.537 ″
	B / C	−56 ° 46 ′ 57.7 ″
Apparent brightness	A.	4.69 likes
	B / C	23.6 / 31.3 mag
Typing:
Spectral class	A.	K5 V
	B / C	T1 V / T6 V
B − V color index	A.	1.06
U − B color index	A.	1.00
Physical Properties:
Absolute vis. Brightness M vis	A.	6.89 likes
	B / C	25.8 / 33.5 mag
Dimensions	A.	(0.778 ± 0.039) M ☉
	B / C	0.045 / 0.027 M ☉
radius	A.	(0.707 ± 0.035) R ☉
	B / C	0.091 / 0.096 R ☉
Luminosity	A.	0.24 L ☉
	B / C	1.9 × 10 −5 / 4.5 × 10 −6 L ☉
Effective temperature	A.	4620 K
	B / C	1276/854 K
Metallicity [Fe / H]	A.	−0.23 ± 0.15 (approx. 40% to 80% of the sun)
	B / C
Rotation time	A.	36 d
	B / C
Age	4 billion
Other names and catalog entries
Bayer name ϵ Indi Cordoba Survey CD −57 ° 8464 Bright Star Catalog HR 8387 [1] Henry Draper Catalog HD 209100 [2] SAO catalog SAO 247287 [3] Hipparcos catalog HIP 108870 [4] Tycho catalog TYC 8817-984-1 [5] TYC [6] WDS catalog WDS J22034-5647 Further designations: FY 845   FK5 825 CI Ind

Epsilon Indi (ε Indi) is a star system in the constellation Indus (Indian) . It is a star of the southern sky and can only be observed south of the 33rd parallel north latitude. With an apparent magnitude of +4.69 mag, the star can only just be seen with open eyes .

Epsilon Indi A, which is by far the brightest and only known component until 2002, belongs to the spectral class K4-5V. The age of the system is unclear, but measurements from 2019 suggest it is around 4 billion years old. It is comparable in size to the sun, but colder.

As seen from Epsilon Indi, the sun is a second magnitude star in the constellation Great Bear .

Proper movement

Epsilon Indi is only 11.8 light-years away from us and is the fixed star with the third largest proper motion after Barnard's Arrow Star and Kapteyn's Star . Its own movement in the night sky is 4.7 arc seconds per year - that is roughly the diameter of the moon in 400 years. In about 1000 years the star system will change over to the neighboring constellation Tukan .

System from Epsilon Indi

planet

In 2018, after the brown dwarfs, a Jupiter analogue with 3 times Jupiter's mass was discovered. Epsilon Indi A b orbits the central star Epsilon Indi A at a distance of 11.5 AU . The orbital period is around 45 years. A special feature of the planet is that although it was discovered using the radial velocity method, it could be characterized much more precisely by combining it with astrometric measurements from the satellites Gaia and Hipparcos . The planet is a good candidate for follow-up investigations by the James Webb Space Telescope because of its close proximity and relatively large distance to the central star .

Brown dwarfs

In 2002 and 2003, Epsilon Indi was recognized as a star system. On the search for planets outside our solar system, astronomers found two mutually orbiting brown dwarfs in 1200 astronomical units distance of Epsilon Indi A . In 2002 the slightly lighter Epsilon Indi B was found, a brown dwarf of the spectral class T1 with a surface temperature of 1200 K and a mass of about 50 Jupiter's masses. A year later, the weaker brown dwarf Epsilon Indi C was found, which belongs to the spectral class T6, has a surface temperature of only 850 K and a mass of about 30 Jupiter's masses. The distance between the two components B (Ba) and C (Bb) is about 2.1 AU; both have a diameter roughly equivalent to that of the planet Jupiter.

Web links

• Epsilon Indi Ba found
• Epsilon Indi Bb found

Individual evidence

1. ↑ ^{a b} Planet eps Ind A b. In: Extrasolar Planets Encyclopaedia . Retrieved November 16, 2019 . 
2. ↑ ^{a b c d e f} eps Ind. In: SIMBAD. Center de Données astronomiques de Strasbourg, accessed November 9, 2018 . 
3. ↑ ^{a b c d} eps Ind B. In: SIMBAD. Center de Données astronomiques de Strasbourg, accessed November 9, 2018 . 
4. ^ SOZ 1. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed November 9, 2018 . 
5. ↑ ^{a b} P. E. Kervella, F. Arenou, F. Mignard, F. Thévenin: Stellar and substellar companions of nearby stars from Gaia DR2. Binarity from proper motion anomaly . In: Astronomy & Astrophysics . 623, p. A72. arxiv : 1811.08902 . bibcode : 2019A & A ... 623A..72K . doi : 10.1051 / 0004-6361 / 201834371 .
6. ↑ ^{a b c d} EPS IND. Jim Kaler, accessed April 14, 2019 . 
7. ↑ ^{a b c d e} Fabo Feng, Guillem Anglada-Escudé, Mikko Tuomi, Hugh RA Jones, Julio Chanamé, Paul R. Butler, Markus Janson: Detection of the nearest Jupiter analog in radial velocity and astrometry data . In: MNRAS . 490, No. 4, October 14, 2019, pp. 5002-5016. arxiv : 1910.06804 . doi : 10.1093 / mnras / stz2912 .
8. ↑ Abia et al .: Abundances of light metals and Ni in a sample of disc stars , Astronomy and Astrophysics 206 (No. 1, Nov. 1988), p. 100ff. bibcode : 1988A & A ... 206..100A .
9. ↑ Discovery of Nearest Known Brown Dwarf: Bright Southern Star Epsilon Indi Has Cool, Substellar Companion , press release 01/03, European Southern Observatory , January 13, 2003. Found September 18, 2007.
10. ↑ R.-D. Scholz, MJ McCaughrean, N. Lodieu, and B. Kuhlbrodt: ε Indi B: A new benchmark T dwarf , Astronomy and Astrophysics 398 (February 2003), pp. L29-L33. bibcode : 2003A & A ... 398L..29S
11. ↑ ^{a b} I. Baraffe, G. Chabrier, T. Barman, F. Allard, and PH Hauschildt: Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 209458 , Astronomy and Astrophysics 402 (May 2003), pp. 701-712. bibcode : 2003A & A ... 402..701B
12. ^ The T-dwarf reported by Scholz et al. (2003) was discovered by Volk et al. (2003) to be a close optical double consisting of an early T dwarf (ε Indi B) and a late T dwarf (ε Indi C) separated by 0.6 arcseconds. With an accurately known distance of 3.626 +/- 0.009 pc, ε Indi Ba and Bb are the nearest known brown dwarfs. They share a common proper motion with the K5V star ε Indi, lying at a projected distance of 1460 AU from their presumed primary star.
13. ↑ K. nation R. Blum, G. Walker, P. Puxley: epsilon Indi B . In: IAU (Ed.): International Astronomical Union Circular . No. 8188, August 27, 2003. bibcode : 2003IAUC.8188 .... 2V .