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| '''Kepler-91b''' is a planet orbiting ], a star slightly more massive than the ]. Kepler-91 has left the main sequence and is now a ] star. | '''Kepler-91b''' is a giant planet orbiting ], a star slightly more massive than the ]. Kepler-91 has left the main sequence and is now a ] star. | ||
| ==Discovery and further confirmation== | ==Discovery and further confirmation== | ||
| Kepler-91b was detected by analyzing the data of ] 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.<ref name="Lillo-Box">{{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}}</ref> | Kepler-91b was detected by analyzing the data of ] 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.<ref name="Lillo-Box">{{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}}</ref> | ||
| Further analysis managed to question the planetary nature of the object, suspecting that it is a self-luminous object |
Further analysis managed to question the planetary nature of the object, suspecting that it is a self-luminous object<ref name="arxiv">{{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}}</ref>. However, the planetary nature was eventually confirmed again through both the radial velocity technique<ref>{{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=2014-08|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}}</ref> and re-analysis of the light curve modulations<ref>{{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}}</ref>. | ||
| ==Characteristics== | ==Characteristics== | ||
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| ==Possible trojan companion== | ==Possible trojan companion== | ||
| The possibility of a ] to Kepler-91b was studied but the conclusion was that the transit-signal was a false-positive.<ref>{{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}}</ref> | The possibility of a ] to Kepler-91b was suggested due to the presence of a small dim in the phase-folded light curve at phase 0.68<ref name="Lillo-Box" />. This was subsequently studied but the conclusion was that the transit-signal was a false-positive.<ref>{{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}}</ref> | ||
| ==References== | ==References== | ||
Revision as of 10:31, 16 September 2018
Template:Planetbox begin Template:Planetbox star Template:Planetbox character Template:Planetbox orbit Template:Planetbox discovery Template:Planetbox catalog Template:Planetbox end
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 confirmation
Kepler-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.
Further analysis managed to question the planetary nature of the object, suspecting that it is a self-luminous object. However, the planetary nature was eventually confirmed again through both the radial velocity technique and re-analysis of the light curve modulations.
Characteristics
Kepler-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.
Possible trojan companion
The 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. This was subsequently studied but the conclusion was that the transit-signal was a false-positive.
References
- ^ Lillo-Box, J.; Barrado, D.; Moya, A.; Montesinos, B.; Montalbán, J.; Bayo, A.; Barbieri, M.; Régulo, C.; Mancini, L.; Bouy, H.; Henning, T. (2013). "Kepler-91b: A planet at the end of its life. Planet and giant host star properties via light-curve variations". Astronomy & Astrophysics. 562: A109. arXiv:1312.3943. Bibcode:2014A&A...562A.109L. doi:10.1051/0004-6361/201322001.
- Sliski, David H.; Kipping, David M. (2014). "A High False Positive Rate for Kepler Planetary Candidates of Giant Stars using Asterodensity Profiling". The Astrophysical Journal. 788 (2): 148. arXiv:1401.1207. Bibcode:2014ApJ...788..148S. doi:10.1088/0004-637X/788/2/148.
- Lillo-Box, J.; Barrado, D.; Henning, Th.; Mancini, L.; Ciceri, S.; Figueira, P.; Santos, N. C.; Aceituno, J.; Sánchez, S. (2014-08). "Radial velocity confirmation of Kepler-91 b". Astronomy & Astrophysics. 568: L1. doi:10.1051/0004-6361/201424587. ISSN 0004-6361.
{{cite journal}}: Check date values in:|date=(help) - Barclay, Thomas; Endl, Michael; Huber, Daniel; Foreman-Mackey, Daniel; Cochran, William D.; MacQueen, Phillip J.; Rowe, Jason F.; Quintana, Elisa V. (2015). "Radial Velocity Observations and Light Curve Noise Modeling Confirm that Kepler-91b is a Giant Planet Orbiting a Giant Star". The Astrophysical Journal. 800 (1): 46. doi:10.1088/0004-637X/800/1/46. ISSN 0004-637X.
- Cite error: The named reference
Esteveswas invoked but never defined (see the help page). - Placek, Ben; Knuth, Kevin H.; Angerhausen, Daniel; Jenkins, Jon M. (2015). "Characterization of Kepler-91b and the Investigation of a Potential Trojan Companion Using EXONEST". The Astrophysical Journal. 814 (2): 147. arXiv:1511.01068. Bibcode:2015ApJ...814..147P. doi:10.1088/0004-637X/814/2/147.
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