Delta1 Telescopii
Star in the constellation Telescopium
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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]
| 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 | |
| Evolutionary stage | subgiant[3] |
| 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] |
| Distance | 710 ± 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 | |
| Mass | 4.52±0.06[3] M☉ |
| Radius | 4.7[6] R☉ |
| Luminosity | 899[3] L☉ |
| Temperature | 12,417[3] K |
| Rotational velocity (v sin i) | 11[3] km/s |
| Age | 178[4] Myr |
| Other designations | |
| δ1 Tel, CD−45°12550, HD 170465, HIP 90830, HR 6934, SAO 229092[7] | |
| Database references | |
| SIMBAD | data |
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]