Wikipedia

Eta Telescopii

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[17] and has a substellar companion orbiting around it, named Eta Telescopii B.[8]

Eta Telescopii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Telescopium
Right ascension 19h 22m 51.20608s[1]
Declination −54° 25′ 26.1456″[1]
Apparent magnitude (V) +5.05[2]
Characteristics
Spectral type A0 Vn[3] + M7V/M8V[4]
B−V color index +0.02[2]
Astrometry
Radial velocity (Rv)−5.6±2.8[5] km/s
Proper motion (μ) RA: 25.824±0.073[1] mas/yr
Dec.: −82.965±0.061[1] mas/yr
Parallax (π)20.6028 ± 0.0988 mas[1]
Distance158.3 ± 0.8 ly
(48.5 ± 0.2 pc)
Absolute magnitude (MV)+1.61[6]
Orbit[7]
PrimaryA
CompanionB
Period (P)~1,100 years
Semi-major axis (a)142+18
−11 AU
Eccentricity (e)0.5±0.1
Inclination (i)79°+5°
−6°°
Details
A
Mass2.09[8] M☉
Radius1.61[9] R☉
Luminosity24[10] L☉
Surface gravity (log g)4.60[11] cgs
Temperature11,941±406[11] K
Rotational velocity (v sin i)330[11] km/s
Age12[10] Myr
B
Mass35+7
−8[7] MJup
Radius2.28±0.03[7] RJup
Luminosity3.311+0.077
−0.075×10−3[7] L☉
Surface gravity (log g)4.3+0.1
−0.2[7] cgs
Temperature2830+20
−30[7] K
Age~1–~2[7] Myr
HD 181327
Mass1.39[12] M☉
Radius1.37[13][a] R☉
Surface gravity (log g)4.48[14] cgs
Temperature6,541[14] K
Metallicity [Fe/H]−0.14±0.08[14] dex
Rotational velocity (v sin i)21[14] km/s
Age14.3±3.1[15]–26[12] Myr
Other designations
η Tel, CPD−54° 9339, HD 181296, HIP 95261, HR 7329, SAO 246055[16]
Database references
SIMBADdata

Characteristics

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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.[17] 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 0.7 and 30 MJ and a semi-major axis of 3–19 AU. 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',[17] is the common proper motion companion HD 181327, a yellow-white main sequence star of spectral type F6V and apparent magnitude 7.0,[18] which is separated from Eta Telescopii from 7' in the sky and has its own debris disk.[17] This disk has a sharply-defined inner edge at 31 AU, indicating a likely planet between 19 and 31 AU from the star.[19]

Substellar companion

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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]

Notes

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  1. ^ From angular diameter and distance

References

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  1. ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  3. ^ a b c Wyatt, M.C.; et al. (July 2007), "Steady State Evolution of Debris Disks around A Stars", The Astrophysical Journal, 663 (1): 365–382, arXiv:astro-ph/0703608, Bibcode:2007ApJ...663..365W, doi:10.1086/518404, S2CID 18883195.
  4. ^ a b Lowrance, Patrick J.; et al. (2000), "A Candidate Substellar Companion to HR 7329", The Astrophysical Journal, 541 (1): 390–95, arXiv:astro-ph/0005047, Bibcode:2000ApJ...541..390L, doi:10.1086/309437, S2CID 14416852.
  5. ^ Youngblood, Allison; et al. (10 November 2021). "A Radiatively Driven Wind from the η Tel Debris Disk". The Astronomical Journal. 162 (6). 235. arXiv:2108.11965. Bibcode:2021AJ....162..235Y. doi:10.3847/1538-3881/ac21d1.
  6. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  7. ^ a b c d e f g h i j Chai, Yiwei; Chen, Christine H.; Worthen, Kadin; Li, Alexis; Sefilian, Antranik; Balmer, William; Hines, Dean C.; Law, David R.; Sargent, B. A. (2024-08-21), A JWST MIRI MRS View of the $\eta$ Tel Debris Disk and its Brown Dwarf Companion, doi:10.48550/arXiv.2408.11692, retrieved 2024-08-23
  8. ^ a b c Nogueira, P. H.; Lazzoni, C.; Zurlo, A.; Bhowmik, T.; Donoso-Oliva, C.; Desidera, S.; Milli, J.; Pérez, S.; Delorme, P. (2024-05-07). "Astrometric and photometric characterization of η Tel B combining two decades of observations". Astronomy & Astrophysics. 687: A301. arXiv:2405.04723. doi:10.1051/0004-6361/202449222.
  9. ^ a b Rhee, Joseph H.; et al. (May 2007), "Characterization of Dusty Debris Disks: The IRAS and Hipparcos Catalogs", The Astrophysical Journal, 660 (2): 1556–1571, arXiv:astro-ph/0609555, Bibcode:2007ApJ...660.1556R, doi:10.1086/509912, S2CID 11879505.
  10. ^ a b c d Smith, R.; et al. (2009), "Resolved debris disc emission around Eta Telescopii: a young solar system or ongoing planet formation?", Astronomy & Astrophysics, 493 (1): 299–308, arXiv:0810.5087, Bibcode:2009A&A...493..299S, doi:10.1051/0004-6361:200810706, S2CID 6588381.
  11. ^ a b c d David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607. For the exceptionally high v sin i value, see the author's comments on p.600.
  12. ^ a b Nielsen, Eric L.; De Rosa, Robert J.; Macintosh, Bruce; Wang, Jason J.; Ruffio, Jean-Baptiste; Chiang, Eugene; Marley, Mark S.; Saumon, Didier; Savransky, Dmitry; Ammons, S. Mark; Bailey, Vanessa P.; Barman, Travis; Blain, Célia; Bulger, Joanna; Burrows, Adam (2019-07-01). "The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics from 10 to 100 au". The Astronomical Journal. 158 (1): 13. arXiv:1904.05358. Bibcode:2019AJ....158...13N. doi:10.3847/1538-3881/ab16e9. ISSN 0004-6256. Data is available here at VizieR.
  13. ^ Cruzalèbes, P.; Petrov, R. G.; Robbe-Dubois, S.; Varga, J.; Burtscher, L.; Allouche, F.; Berio, P.; Hofmann, K. -H.; Hron, J.; Jaffe, W.; Lagarde, S.; Lopez, B.; Matter, A.; Meilland, A.; Meisenheimer, K. (2019-12-01). "A catalogue of stellar diameters and fluxes for mid-infrared interferometry". Monthly Notices of the Royal Astronomical Society. 490 (3): 3158–3176. arXiv:1910.00542. Bibcode:2019MNRAS.490.3158C. doi:10.1093/mnras/stz2803. ISSN 0035-8711. available here in VizieR.
  14. ^ a b c d Chavero, C.; de la Reza, R.; Ghezzi, L.; Llorente de Andrés, F.; Pereira, C. B.; Giuppone, C.; Pinzón, G. (2019-08-01). "Emerging trends in metallicity and lithium properties of debris disc stars". Monthly Notices of the Royal Astronomical Society. 487 (3): 3162–3177. arXiv:1905.12066. Bibcode:2019MNRAS.487.3162C. doi:10.1093/mnras/stz1496. ISSN 0035-8711. Data about this star is available here in VizieR.
  15. ^ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011-01-01). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. ISSN 0035-8711. Data is available here at VizieR.
  16. ^ "eta Tel". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-08.{{cite web}}: CS1 maint: postscript (link)
  17. ^ a b c d Neuhäuser, R.; Ginski, C.; Schmidt, T.O.B.; Mugrauer, M. (2011), "Further Deep Imaging of HR 7329 A (η Tel A) and its Brown Dwarf Companion B", Monthly Notices of the Royal Astronomical Society, 416 (2): 1430–35, arXiv:1106.1388, Bibcode:2011MNRAS.416.1430N, doi:10.1111/j.1365-2966.2011.19139.x, S2CID 118833354.
  18. ^ "HD 181327". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-08.{{cite web}}: CS1 maint: postscript (link)
  19. ^ Nesvold, Erika R.; Kuchner, Marc J. (2015), "Gap Clearing by Planets in a Collisional Debris Disk", The Astrophysical Journal, 798 (2): 10, arXiv:1410.7784, Bibcode:2015ApJ...798...83N, doi:10.1088/0004-637X/798/2/83, S2CID 118667155, 83.
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