Eta Telescopii

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Template:Short description

Eta Telescopii
File:Eta Telescopii legacy dr10.jpg
Eta Telescopii and HD 181327 with the legacy surveys
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Telescopium
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) +5.05[2]
Characteristics
Spectral type A0 Vn[3] + M7V/M8V[4]
B−V Template:Engvar +0.02[2]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[5] km/s
Proper motion (μ) RA: Script error: No such module "val".[1] mas/yr
Dec.: Script error: No such module "val".[1] mas/yr
Parallax (π)20.6028±0.0988 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+1.61[6]
Orbit[7]
PrimaryA
CompanionB
Period (P)~1,100 years
Semi-major axis (a)Script error: No such module "val".
Eccentricity (e)Script error: No such module "val".
Inclination (i)Script error: No such module "val".°
Details
A
Mass2.09[8] Template:Solar mass
Radius1.61[9] Template:Solar radius
Luminosity24[10] Template:Solar luminosity
Surface gravity (log g)4.60[11] cgs
TemperatureScript error: No such module "val".[11] K
Rotational velocity (v sin i)330[11] km/s
Age12[10] Myr
B
MassScript error: No such module "val".[7] MJup
RadiusScript error: No such module "val".[7] RJup
LuminosityScript error: No such module "val".[7] Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val".[7] cgs
TemperatureScript error: No such module "val".[7] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Age~1–~2[7] Myr
Other designations
Template:Odlist[12]
Database references
SIMBADdata

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Eta Telescopii (η Telescopii) is a white-hued star in the southern constellation of Telescopium. This is an A-type main sequence star with an apparent visual magnitude of +5.03. It is approximately 158 light years from Earth[1] and is a member of the Beta Pictoris Moving Group of stars that share a common motion through space.[10] It forms a wide binary system with the star HD 181327[13] and has a substellar companion orbiting around it, named Eta Telescopii B.[8]

Characteristics

Eta Telescopii is an A-type main-sequence star with 2.09 times the mass and 1.61 times the Sun's radius. It is radiating around 24 times the Sun's luminosity from its photosphere at an effective temperature of 11,941 K. The age of the star is only about 12 million years.[3][8][9][11][10] It is emitting an excess of infrared radiation that suggests the presence of a circumstellar disk of dust at an orbital radius of 24 AU, and an unresolved asteroid belt at 4 AU from the host star.[3] Subsequent imaging showed there were no objects of 20 Jupiter masses or greater between the disk and the brown dwarf, leading the researchers Neuhäuser and colleagues to postulate that the brown dwarf had an eccentric orbit – if 200 AU were its furthest distance from the primary (apocenter), then it could come as close as 71 AU with an average distance of 136 AU.[13] More recent observations support this hypothesis, as Eta Telescopii B was found to have an eccentricity of 0.5 and an apocenter of 214 AU, close to its current distance of 209 AU.[7]

Observations with the MIRI spectometer aboard the James Webb Space Telescope show that the disk is axisymmetrical and possibly misaligned with the companion Eta Telescopii B. This suggest that, in the simplest scenario, there is an additional planet that have not been detected. The planet is expected to have a mass between Template:Jupiter mass and a semi-major axis of Script error: No such module "val".. Further modelling of the disk's parameters is needed to reduce uncertainites and determine if it is really misaligned.[7]

Eta Telescopii is in fact a triple star system; further away, separated by 7',[13] is the common proper motion companion HD 181327, a yellow-white main sequence star of spectral type F6V and apparent magnitude 7.0,[14] which is separated from Eta Telescopii from 7' in the sky and has its own debris disk.[13] This disk has a sharply-defined inner edge at 82 AU, indicating a likely planet between 55 and 82.3 AU from the star.[15][16]

Substellar companion

In 1998, imaging with the Hubble Space Telescope revealed a 12th magnitude object around 4" distant from Eta Telescopii, and calculated to be a brown dwarf of spectral type M7V or M8V with a surface temperature of around 2600 K.[4] This companion, named Eta Telescopii B, takes 1,100 years to complete an orbit and has an orbital distance that varies from 71 AU in the periapsis, to 213 AU in the apoapsis. It has a mass estimated to be 35 times the mass of Jupiter, while its radius is 2.3 times the radius of Jupiter.[7]

References

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  1. ↑ a b c d e f Template:Cite Gaia EDR3
  2. ↑ a b Script error: No such module "citation/CS1".
  3. ↑ a b c Script error: No such module "citation/CS1".
  4. ↑ a b Script error: No such module "citation/CS1".
  5. ↑ Script error: No such module "Citation/CS1".
  6. ↑ Script error: No such module "citation/CS1".
  7. ↑ a b c d e f g h i j Script error: No such module "Citation/CS1".
  8. ↑ a b c Script error: No such module "Citation/CS1".
  9. ↑ a b Script error: No such module "citation/CS1".
  10. ↑ a b c d Script error: No such module "citation/CS1".
  11. ↑ a b c d Script error: No such module "citation/CS1". For the exceptionally high v sin i value, see the author's comments on p.600.
  12. ↑ Template:Cite simbad
  13. ↑ a b c d Script error: No such module "citation/CS1".
  14. ↑ Template:Cite simbad
  15. ↑ Script error: No such module "Citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".

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Template:Stars of Telescopium

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