| 词条 | HD 181342 |
| 释义 |
|epoch=J2000 |constell=Sagittarius |ra={{RA|19|21|04.23095}}[1] |dec={{DEC|-23|37|10.4528}}[1] |appmag_v=7.55 }}{{Starbox character |class=K0 III[2] |b-v=+1.02 }}{{Starbox astrometry |radial_v=−0.76 ± 0.07[3] |prop_mo_ra=−45.87[1] |prop_mo_dec=−30.58[1] |parallax=9.04 |p_error=0.61 |parallax_footnote=[1] |absmag_v=2.2 ± 0.2 }}{{Starbox detail |source=[3] |mass=1.78 ± 0.11 |radius=4.55 ± 0.49 |temperature=4976 ± 26 |luminosity=16.2 |gravity=3.42 ± 0.07 |metal_fe=+0.22 ± 0.05 |rotational_velocity=1.92 ± 0.23 |age_gyr=1.56 ± 0.28 }}{{Starbox catalog |names={{odlist|CD=-23° 15307|CPD=-23° 7442|HD=181342|HIP=95124|SAO=188005}}[4] }}{{Starbox reference |Simbad=HD+181342 }}{{Starbox end}}HD 181342 is a star in the constellation of Sagittarius. With an apparent magnitude of 7.55, it cannot be seen with the naked eye. Parallax measurements made by Hipparcos put the star at a distance of 360 light-years (111 parsecs) away.[1] HD 181342 is a K-type red giant star.[2] It was formerly an A-type main-sequence star, but at an age of 1.56 billion years it has swelled up to a size of 4.55 solar radii.[3] It is currently 1.78 times the mass of the Sun, 16.2 times as luminous, and its surface temperature is 4976 K.[3] Planetary systemHD 181342 is known to have one planet, detected with Doppler spectroscopy. The planet, HD 181342 b, orbits at a distance of 1.78 astronomical units (au), every 663 days (almost 2 years). Its mass is at least 3.3 times that of Jupiter. {{OrbitboxPlanet begin| table_ref = }}{{OrbitboxPlanet | exoplanet = b | mass = >3.3 ± 0.2 | radius = | semimajor = 1.78 ± 0.07 | period = 663 ± 29 | eccentricity = 0.177 ± 0.057 | inclination = }}{{Orbitbox end}} References1. ^1 2 3 4 5 {{cite journal|title=Validation of the new Hipparcos reduction|author=van Leeuwen, F.|display-authors=etal|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|date=2007|arxiv=0708.1752|bibcode=2007A&A...474..653V|doi=10.1051/0004-6361:20078357}} 2. ^1 {{cite journal|bibcode=1988mcts.book.....H|title=Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0.|journal=Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars|volume=4|author1=Houk, N.|author2=Smith-Moore, M.|year=1988}} 3. ^1 2 3 {{cite journal|title=Stellar parameters and chemical abundances of 223 evolved stars with and without planets|author1=Jofré, E.|author2=Petrucci, R.|author3=Saffe, C.|author4=Saker, L.|author5=de la Villarmois, E. Artur|author6=Chavero, C.|author7=Gómez, M.|author8=Mauas, P. J. D.|journal=Astronomy & Astrophysics|volume=574|pages=A50|date=2015|bibcode=2015A&A...574A..50J|doi=10.1051/0004-6361/201424474|arxiv=1410.6422}} 4. ^{{cite simbad|title=HD 181342|accessdate=3 September 2017}} }}{{Stars of Sagittarius}} 6 : K-type giants|Sagittarius (constellation)|Durchmusterung objects|Henry Draper Catalogue objects|Hipparcos objects|Planetary systems |
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