Delta1 Telescopii

Delta1 Telescopii is a blue-white-hued binary star[5] system in the southern constellation of Telescopium. It is faintly visible to the naked eye, having an apparent visual magnitude of 4.94.[2] Based upon an annual parallax shift of 4.61 mas as seen from Earth,[1] this system is roughly 710 light-years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.29 due to interstellar dust.[4]

For other stars with this Bayer designation, see δ Telescopii.
Delta1 Telescopii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Telescopium
Right ascension 18h 31m 45.43288s[1]
Declination −45° 54′ 53.3166″[1]
Apparent magnitude (V) 4.94[2]
Characteristics
Spectral type B6 IV[3]
U−B color index −0.438[2]
B−V color index −0.121[2]
Astrometry
Proper motion (μ) RA: −3.75[1] mas/yr
Dec.: −27.43[1] mas/yr
Parallax (π)4.61 ± 0.19 mas[1]
Distance710 ± 30 ly
(217 ± 9 pc)
Absolute magnitude (MV)−0.74[4]
Orbit[5]
Period (P)18.8456 d
Eccentricity (e)0.51
Periastron epoch (T)2435003.693 JD
Argument of periastron (ω)
(secondary)		78°
Semi-amplitude (K1)
(primary)		65.0 km/s
Details
δ1 Tel A
Mass4.52±0.06[3] M☉
Radius4.7[6] R☉
Luminosity899[3] L☉
Temperature12,417[3] K
Rotational velocity (v sin i)11[3] km/s
Age178[4] Myr
Other designations
δ1 Tel, CD−45° 12550, HD 170465, HIP 90830, HR 6934, SAO 229092[7]
Database references
SIMBADdata

This system is a single-lined spectroscopic binary with an orbital period of 18.8 days and an eccentricity of 0.51.[5] The estimated size of the semimajor axis has a minimum of 14.5×106 km, with the uncertainty due to lack of a value for the orbital inclination.[8] The primary, component A, has a stellar classification of B6 IV,[3] suggesting it is an evolving B-type subgiant star. Delta1 Telescopii has an estimated 4.5[3] times the mass of the Sun and about 4.7[6] times the Sun's radius. It is radiating 899[3] times the solar luminosity from its photosphere at an effective temperature of 12,417 K.[3]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement, 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168.
  3. Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
  4. Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035, S2CID 119108982.
  5. Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424: 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
  6. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  7. "del01 Tel -- Spectroscopic binary", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-06-07.
  8. Buscombe, W.; Kennedy, P. M. (August 1962), "Two B-Type Spectroscopic Binaries", Publications of the Astronomical Society of the Pacific, 74 (439): 323, Bibcode:1962PASP...74..323B, doi:10.1086/127818.
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