Delta1 Telescopii
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Telescopium |
| Right ascension | 18h 31m 45.43288s |
| Declination | −45° 54′ 53.3166″ |
| Apparent magnitude (V) | 4.94 |
| Characteristics | |
| Evolutionary stage | subgiant |
| Spectral type | B6 IV |
| U−B color index | −0.438 |
| B−V color index | −0.121 |
| Astrometry | |
| Proper motion (μ) | RA: −3.75 mas/yr Dec.: −27.43 mas/yr |
| Parallax (π) | 4.61±0.19 mas |
| Distance | 710 ± 30 ly (217 ± 9 pc) |
| Absolute magnitude (MV) | −0.74 |
| Orbit | |
| 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 M☉ |
| Radius | 4.7 R☉ |
| Luminosity | 899 L☉ |
| Temperature | 12,417 K |
| Rotational velocity (v sin i) | 11 km/s |
| Age | 178 Myr |
| Other designations | |
| δ1 Tel, CD−45°12550, HD 170465, HIP 90830, HR 6934, SAO 229092 | |
| Database references | |
| SIMBAD | data |
Delta1 Telescopii is a blue-white-hued binary star system in the southern constellation of Telescopium. It is faintly visible to the naked eye, having an apparent visual magnitude of 4.94. Based upon an annual parallax shift of 4.61 mas as seen from Earth, 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.
This system is a single-lined spectroscopic binary with an orbital period of 18.8 days and an eccentricity of 0.51. 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. The primary, component A, has a stellar classification of B6 IV, suggesting it is an evolving B-type subgiant star. Delta1 Telescopii has an estimated 4.5 times the mass of the Sun and about 4.7 times the Sun's radius. It is radiating 899 times the solar luminosity from its photosphere at an effective temperature of 12,417 K.