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.[6] 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).[3] It is one of the closest and hence brightest pre-main-sequence stars to Earth.[8]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Telescopium |
| Right ascension | 18h 53m 05.87351s[2] |
| Declination | −50° 10′ 49.8974″[2] |
| Apparent magnitude (V) | 8.33 - 8.63[3] |
| Characteristics | |
| Spectral type | G9 IV[4] + M7±1[5] |
| B−V color index | +0.784±0.021[6] |
| Variable type | BY Dra[3] |
| Astrometry | |
| Radial velocity (Rv) | −4.2±0.2[6] km/s |
| Proper motion (μ) | RA: +16.272(18) mas/yr[2] Dec.: −85.519(17) mas/yr[2] |
| Parallax (π) | 21.1621 ± 0.0223 mas[2] |
| Distance | 154.1 ± 0.2 ly (47.25 ± 0.05 pc) |
| Absolute magnitude (MV) | 4.88[6] |
| Orbit[7] | |
| Period (P) | 120+110 −30 yr |
| Semi-major axis (a) | 27+14 −4 AU |
| Eccentricity (e) | 0.52+0.08 −0.10 |
| Inclination (i) | 91.73+0.36 −0.32° |
| Longitude of the node (Ω) | 238.62+0.21 −0.23° |
| Periastron epoch (T) | 1997.2+4.7 −1.8 |
| Argument of periastron (ω) (secondary) | 50+50 −30° |
| Details[8] | |
| Mass | 1.13±0.03 M☉ |
| Radius | 1.23±0.04 R☉ |
| Luminosity | 0.993+0.004 −0.005[9] 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[5] |
| Rotational velocity (v sin i) | 69.0±0.1[4] km/s |
| Age | 24±3 Myr |
| B | |
| Mass | 27+25 −9[7] MJup |
| Surface gravity (log g) | < 4.5[5] 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.[8] The star has a high rate of spin, showing a projected rotational velocity of 69 km/s[4] and a rotation period of 22.6 h.[5] 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.[8]
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 about 36 times the mass of Jupiter orbiting at a distance of about 16 AU, discovered in 2009.[11] 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.[8] Preliminary orbital elements from 2016 give a best fit orbital period of 622.2 years with an eccentricity of 0.755.[5]
The mass and orbit of this companion were updated in 2023 based on Hipparcos and Gaia astrometry, finding a somewhat lower mass, and an edge-on orbit that is eccentric but less so than previous results.[7] It is now included in the NASA Exoplanet Archive since its nominal mass of 27 MJ is below their upper limit of 30 MJ, although the margin of error is large enough that it is still possible that the mass exceeds 30 MJ.[12][13]
References
edit- ^ Innis, J. L.; Coates, D. W.; Thompson, K.; Lloyd Evans, T. (January 1990). "Observations of active-chromosphere stars III - photometry of PZ Tel 1979-1985". Monthly Notices of the Royal Astronomical Society. 242 (3): 306–310. Bibcode:1990MNRAS.242..306I. doi:10.1093/mnras/242.3.306.
- ^ a b c d Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c 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. S2CID 125853869.
- ^ a b c 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. S2CID 16080025.
- ^ a b c d e 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. S2CID 44360238. A56.
- ^ a b c d 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.
- ^ a b c Franson, Kyle; Bowler, Brendan P. (June 2023). "Dynamical Mass of the Young Brown Dwarf Companion PZ Tel B". The Astronomical Journal. 165 (6): 246. arXiv:2304.01302. Bibcode:2023AJ....165..246F. doi:10.3847/1538-3881/acca18.
- ^ a b c d e 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. S2CID 18735984.
- ^ 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.
- ^ "V* PZ Tel". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 1 July 2014.
- ^ Biller, Beth A.; Liu, Michael C.; et al. (September 2010). "The Gemini NICI Planet-finding Campaign: Discovery of a Close Substellar Companion to the Young Debris Disk Star PZ Tel". The Astrophysical Journal Letters. 720 (1): L82–L87. arXiv:1007.4808. Bibcode:2010ApJ...720L..82B. doi:10.1088/2041-8205/720/1/L82.
- ^ "PZ Tel". NASA Exoplanet Archive. Retrieved 29 May 2023.
- ^ "Exoplanet Criteria for Inclusion in the Archive". NASA Exoplanet Archive. Retrieved 29 May 2023.
External links
edit- Watson, Christopher (19 April 2012). "PZ Telescopii". AAVSO Website. American Association of Variable Star Observers. Retrieved 1 July 2014.