| 词条 | Aldebaran b |
| 释义 |
| name = Aldebaran b | image = Aldebaran b exoplanet.jpg | caption = An artist's impression of Aldebaran b as an exoplanet. | discovered = 1993 (dubious) May 15, 2015 (confirmed) | discovery_method = Radial velocity | apsis = astron | aphelion = 1.606 {{±|0.2105|0.2375}} AU | perihelion = 1.314 {{±|0.3295|0.3025}} AU | semimajor = {{convert|1.46|±|0.27|AU|km|abbr=on}} | eccentricity = 0.1 ± 0.05 | period = 628.96 ± 0.9 d | time_periastron = 1999/04/28 ± 50 | arg_peri = 287 ± 29 | star = Aldebaran | mass = {{val|5.8|0.7}}[1] {{Jupiter mass|link=y}} | single_temperature = {{convert|1500|K|C F}} }}Aldebaran b is an exoplanet orbiting the orange giant star Aldebaran, 65 light-years away. It was initially detected in 1993, but was considered doubtful until in 2015, when researchers came to a conclusion that there is likely an exoplanet orbiting Aldebaran, consistent with the original calculations, but also compatible with stellar activity.[2] Physical propertiesMass and orbitAldebaran b is a giant exoplanet with about 6.5 times the mass of Jupiter. It orbits at a distance about 45% farther than Earth does from the Sun. The equilibrium temperature of this planet is likely to be around {{convert|1500|K|C F}}, as it is strongly irradiated by its giant host star. Nevertheless, when Aldebaran was a main sequence star, it is likely that the planet had an equilibrium temperature comparable to that of the Earth.[1] Host starThe host star, Aldebaran, is an orange giant star, meaning it has moved off from the main sequence and exhausted the supply of hydrogen in the core. It has a spectral class of K5 III.[3] Aldebaran is a K-type star that is 1.16 ± 0.07 times the mass[1] and 44 times the radius of the Sun. It has a surface temperature of 3,910 K. In comparison, the Sun has a surface temperature of 5778 K.[4] The star's average apparent magnitude, or how bright it usually appears from Earth, is 0.86, easily visible to the naked eye. Discovery1993 proposalThe exoplanet was first proposed in 1993, radial velocity measurements of Aldebaran, Arcturus and Pollux showed that Aldebaran exhibited a long-period radial velocity oscillation, which could be interpreted as a substellar companion. The measurements for Aldebaran implied a companion with a minimum mass 11.4 times that of Jupiter in a 643-day orbit at a separation of {{convert|2.0|AU|Gm|abbr=on}} in a mildly eccentric orbit. However, all three stars surveyed showed similar oscillations yielding similar companion masses, and the authors concluded that the variation was likely to be intrinsic to the star rather than due to the gravitational effect of a companion.[5] 2015 confirmed statusIn 2015, a study showed stable long-term evidence for both a planetary companion and stellar activity.[6] 2019 doubts on existenceIn 2019, an analysis of additional data provided by Lick Observatory has placed a serious doubt on existence of Aldebaran b, because of apparent phase jitter of radial-velocity signal, therefore better data fit is obtained by either two planets or no planets at all around Aldebaran.[7] See also
References1. ^1 2 {{cite journal | last1=Farr | first1=W. | title=Aldebaran b's temperate past uncovered in planet search data | bibcode=2018arXiv180209812F|arxiv = 1802.09812 }} 2. ^{{Cite journal | arxiv=1505.03454 | title=Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity | date=May 15, 2015 | author=Hatzes, A.P. | display-authors=etal | pages=18|bibcode = 2015yCat..35800031H |doi = 10.1051/0004-6361/201425519 }} 3. ^{{cite journal|bibcode=2006AJ....132..161G|title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample|journal=The Astronomical Journal|volume=132|pages=161|author1=Gray|first1=R. O.|last2=Corbally|first2=C. J.|last3=Garrison|first3=R. F.|last4=McFadden|first4=M. T.|last5=Bubar|first5=E. J.|last6=McGahee|first6=C. E.|last7=O'Donoghue|first7=A. A.|last8=Knox|first8=E. R.|year=2006|doi=10.1086/504637|arxiv = astro-ph/0603770 }} 4. ^{{cite web|url=http://www.universetoday.com/18092/temperature-of-the-sun/ |title=Temperature of the Sun|author=Fraser Cain |date=15 September 2008 |work= |publisher=Universe Today |accessdate=19 February 2011}} 5. ^{{cite journal|bibcode=1993ApJ...413..339H | doi = 10.1086/173002|title=Long-period radial velocity variations in three K giants|last1=Hatzes |first1=A.|last2=Cochran |first2=W.|journal=The Astrophysical Journal|volume=413|issue=1|pages=339–348|date=1993}} 6. ^{{Cite journal|bibcode=2015A&A...580A..31H|last1=Hatzes|first1=A. P.|last2=Cochran|first2=W. D.|title=Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity|arxiv=1505.03454|display-authors=etal|doi = 10.1051/0004-6361/201425519 }} 7. ^{{cite arXiv |last=Reichert |first=Katja |eprint=1903.09157 |title=Precise radial velocities of giant stars XII. Evidence against the proposed planet Aldebaran b |class=astro-ph.EP |date=25 March 2019}} External links
6 : Aldebaran|Exoplanets|Hot Jupiters|Exoplanets discovered in 1998|Exoplanets discovered in 2015|Taurus (constellation) |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。