PZ Telescopii
PZ Telescopii, also known as HD 174429 or simply PZ Tel, is a young star in the constellation Telescopium. Based on parallax measurements, it is located at a distance of 154 light years from the Sun. The star is drifting closer with a radial velocity of −4 km/s.[5] It is too faint to be visible to the naked eye and is classified as a BY Draconis variable that ranges in apparent visual magnitude from 8.33 down to 8.63 over a period of 22.581 hours (0.94088 days).[2] It is one of the closest and hence brightest pre-main-sequence stars to Earth.[6]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Telescopium |
| Right ascension | 18h 53m 05.87338s[1] |
| Declination | −50° 10′ 49.9014″[1] |
| Apparent magnitude (V) | 8.33 - 8.63[2] |
| Characteristics | |
| Spectral type | G9 IV[3] + M7±1[4] |
| B−V color index | +0.784±0.021[5] |
| Variable type | BY Dra[2] |
| Astrometry | |
| Radial velocity (Rv) | −4.2±0.2[5] km/s |
| Proper motion (μ) | RA: +16.348±0.084[1] mas/yr Dec.: −85.254±0.084[1] mas/yr |
| Parallax (π) | 21.2186 ± 0.0602[1] mas |
| Distance | 153.7 ± 0.4 ly (47.1 ± 0.1 pc) |
| Absolute magnitude (MV) | 4.88[5] |
| Orbit[4] | |
| Period (P) | 622.2 yr |
| Semi-major axis (a) | 1.504″ |
| Eccentricity (e) | 0.755 |
| Inclination (i) | 92.05° |
| Longitude of the node (Ω) | 58.43° |
| Periastron epoch (T) | 2000.0 |
| Argument of periastron (ω) (secondary) | 264.38° |
| Details[6] | |
| Mass | 1.13±0.03 M☉ |
| Radius | 1.23±0.04 R☉ |
| Luminosity | 0.993+0.004 −0.005[1] L☉ |
| Surface gravity (log g) | 4.41±0.10 cgs |
| Temperature | 5,338±200 K |
| Metallicity [Fe/H] | +0.05±0.20 dex |
| Rotation | 0.943±0.002[4] |
| Rotational velocity (v sin i) | 69.0±0.1[3] km/s |
| Age | 24±3 Myr |
| B | |
| Mass | 38–72[4] MJup |
| Surface gravity (log g) | < 4.5[4] cgs |
| Temperature | 2,700±100 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
PZ Telescopii has an effective surface temperature of around 5,338 K (the Sun has an approximate surface temperature of 5,778 K), a mass around 1.13 times, and diameter 1.23 times that of the Sun.[6] The star has a high rate of spin, showing a projected rotational velocity of 69 km/s[3] and a rotation period of 22.6 h.[4] It is radiating about the same luminosity as the Sun. PZ Telescopii was originally considered to be a member of the Beta Pictoris moving group; however in a 2012 paper, James Jenkins of Universidad de Chile and colleagues used three methods to calculate its age and came up with a figure of around 24 million years—significantly older than the 12 million years of the association.[6]
This star has an orbiting debris disk calculated to span from a radius of 35 to 165 astronomical units (AU), as well as a substellar companion with 36 times the mass of Jupiter orbiting at a distance of 16 AU, discovered in 2008. The companion, currently known as PZ Tel B, is thought to be a brown dwarf; however it is possible (though very unlikely) that it is an extremely large Jupiter-like planet, in which case it would be PZ Tel b, and the first such planet to be directly imaged.[6] Preliminary orbital elements give a best fit orbital period of 622.2 years with an eccentricity of 0.755.[4]
References
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085.
- Torres, C. A. O.; Quast, G. R.; Silva, L. da; Reza, R. de la; Melo, C. H. F.; Sterzik, M. (December 1, 2006). "Search for associations containing young stars (SACY) - I. Sample and searching method". Astronomy & Astrophysics. 460 (3): 695–708. arXiv:astro-ph/0609258. Bibcode:2006A&A...460..695T. doi:10.1051/0004-6361:20065602. ISSN 0004-6361.
- Maire, A. -L.; et al. (March 2016). "First light of the VLT planet finder SPHERE. II. The physical properties and the architecture of the young systems PZ Telescopii and HD 1160 revisited". Astronomy & Astrophysics. 587: 24. arXiv:1511.04072. Bibcode:2016A&A...587A..56M. doi:10.1051/0004-6361/201526594. A56.
- 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.
- Jenkins, J. S.; Pavlenko, Y. V.; Ivanyuk, O.; Gallardo, J.; et al. (2012). "Benchmark Cool Companions: Ages and Abundances for the PZ Telescopii System". Monthly Notices of the Royal Astronomical Society. 420 (4): 3587–98. arXiv:1111.7001. Bibcode:2012MNRAS.420.3587J. doi:10.1111/j.1365-2966.2011.20280.x.
- "V* PZ Tel". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 1 July 2014.
External links
- Watson, Christopher (19 April 2012). "PZ Telescopii". AAVSO Website. American Association of Variable Star Observers. Retrieved 1 July 2014.