| 词条 | Kepler-91b |
| 释义 |
| name = Kepler-91b | discovered = 2013 | discovery_method = Transit (Kepler Mission) | apsis = astron | semimajor = {{val|0.072|+0.007|-0.002}} AU | period = {{val|6.24658}} d | inclination = {{val|68.5|+1.6|-1}} | star = Kepler-91 | mean_radius = {{val|1.322|+0.094|-0.086}} {{Jupiter radius|link=y}} | mass = {{val|0.88|+0.33|-0.17}} {{Jupiter mass|link=y}} | density = {{convert|0.44|g/cm3|lk=on|abbr=on}} | albedo = 0.39 [1] | single_temperature = {{val|2132|u=K}} }} Kepler-91b is a giant planet orbiting Kepler-91, a star slightly more massive than the Sun. Kepler-91 has left the main sequence and is now a red giant branch star. Discovery and further confirmationKepler-91b was detected by analyzing the data of Kepler spacecraft where a transit-like signal was found. Initially thought to be a false positive due to light curve variations by a self-luminous object, it was later revealed that due to low density of Kepler-91's shape is distorted to slightly ellipsoidal shape due to gravitational effects of the planet. Ellipsoidal light variations caused by Kepler-91b constitute more than the third of light variations compared to transit depth. Ellipsoidal light variations also allowed to determine the planet's mass. It was also found that Kepler-91b reflects some of the starlight from its star.[2] Further analysis managed to question the planetary nature of the object, suspecting that it is a self-luminous object[3]. However, the planetary nature was eventually confirmed again through both the radial velocity technique[4] and re-analysis of the light curve modulations[5]. CharacteristicsKepler-91b is about 14% less massive than Jupiter while being more than 35% larger, making it less than half of the density of water. Kepler-91b orbits around the host star in about 6.25 days. Despite being one of the least edge-on orbits relative to Earth with inclination being about 68.5 degrees, transit was detected due to low semi-major axis to host star radius ratio. Kepler-91b is expected to be engulfed by the parent star within about 55 million years.[2][1] Possible trojan companionThe possibility of a trojan planet to Kepler-91b was suggested due to the presence of a small dim in the phase-folded light curve at phase 0.68[2]. This was subsequently studied but the conclusion was that the transit-signal was a false-positive.[6] References1. ^1 {{Cite journal|arxiv=1407.2245|last1= Esteves|first1= Lisa J.|title= Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry|journal= The Astrophysical Journal|volume= 804|issue= 2|pages= 150|last2= De Mooij|first2= Ernst J. W.|last3= Jayawardhana|first3= Ray|year= 2014|doi= 10.1088/0004-637X/804/2/150|bibcode= 2015ApJ...804..150E}} 2. ^1 2 {{Cite journal|arxiv=1312.3943|last1= Lillo-Box|first1= J.|title= Kepler-91b: A planet at the end of its life. Planet and giant host star properties via light-curve variations|journal= Astronomy & Astrophysics|volume= 562|pages= A109|last2= Barrado|first2= D.|last3= Moya|first3= A.|last4= Montesinos|first4= B.|last5= Montalbán|first5= J.|last6= Bayo|first6= A.|last7= Barbieri|first7= M.|last8= Régulo|first8= C.|last9= Mancini|first9= L.|last10= Bouy|first10= H.|last11= Henning|first11= T.|year= 2013|doi= 10.1051/0004-6361/201322001|bibcode= 2014A&A...562A.109L}} 3. ^{{Cite journal|last1=Sliski|first1=David H.|last2=Kipping|first2=David M.|year=2014|title=A High False Positive Rate for Kepler Planetary Candidates of Giant Stars using Asterodensity Profiling|journal=The Astrophysical Journal|volume=788|issue=2|pages=148|arxiv=1401.1207|bibcode=2014ApJ...788..148S|doi=10.1088/0004-637X/788/2/148}} 4. ^{{Cite journal|last=Lillo-Box|first=J.|last2=Barrado|first2=D.|last3=Henning|first3=Th.|last4=Mancini|first4=L.|last5=Ciceri|first5=S.|last6=Figueira|first6=P.|last7=Santos|first7=N. C.|last8=Aceituno|first8=J.|last9=Sánchez|first9=S.|date=August 2014|title=Radial velocity confirmation of Kepler-91 b|url=https://www.aanda.org/articles/aa/abs/2014/08/aa24587-14/aa24587-14.html|journal=Astronomy & Astrophysics|language=en|volume=568|pages=L1|doi=10.1051/0004-6361/201424587|issn=0004-6361}} 5. ^{{Cite journal|last=Barclay|first=Thomas|last2=Endl|first2=Michael|last3=Huber|first3=Daniel|last4=Foreman-Mackey|first4=Daniel|last5=Cochran|first5=William D.|last6=MacQueen|first6=Phillip J.|last7=Rowe|first7=Jason F.|last8=Quintana|first8=Elisa V.|date=2015|title=Radial Velocity Observations and Light Curve Noise Modeling Confirm that Kepler-91b is a Giant Planet Orbiting a Giant Star|url=http://stacks.iop.org/0004-637X/800/i=1/a=46|journal=The Astrophysical Journal|language=en|volume=800|issue=1|pages=46|doi=10.1088/0004-637X/800/1/46|issn=0004-637X}} 6. ^{{Cite journal|arxiv=1511.01068|last1=Placek|first1=Ben|title=Characterization of Kepler-91b and the Investigation of a Potential Trojan Companion Using EXONEST|journal=The Astrophysical Journal|volume=814|issue=2|pages=147|last2= Knuth|first2=Kevin H.|last3=Angerhausen|first3=Daniel|last4= Jenkins|first4=Jon M.|year=2015|doi=10.1088/0004-637X/814/2/147|bibcode=2015ApJ...814..147P}} External links
3 : Exoplanets discovered in 2013|Transiting exoplanets|Exoplanets discovered by Kepler (spacecraft) |
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