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{{Infobox planet
{{Planetbox begin
| name=Kepler-91b | name = Kepler-91b
<!-- DISCOVERY -->
| discovered = 2013
⚫ | discovery_method = ] (])
<!-- DESIGNATIONS -->
<!-- ORBITAL -->
| apsis = astron
| semimajor = {{val|0.072|+0.007|-0.002}} ]
| period = {{val|6.24658}} ]
⚫ | inclination = {{val|68.5|+1.6|-1}}
⚫ | star = ]
<!-- PHYS CHARS -->
| 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 <ref name="Esteves">{{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|s2cid= 117798959}}</ref>
| single_temperature = {{val|2132|u=K}}
<!-- ATMOSPHERE -->
<!-- NOTES -->
}} }}
⚫ '''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.
{{Planetbox star
⚫ | star = ]
| constell = ]
| RA = {{RA|19|02|41.0}}
| DEC = {{DEC|+44|07|00}}
| dist_pc = 1030 ±150
| dist_ly = 3360
| app_mag = 12.9
| mass = 1.31 ±0.1
| radius = 6.3 ±0.16
| temperature = 4550 ±75
| metallicity = 0.11 ± 0.07
| age = 4.86 ± 2.13
⚫ }}
{{Planetbox character
| mass = 0.88{{±|0.33|0.17}}
| radius = 1.322 {{±|0.094|0.086}}
| stellar_flux =
| density_cgs = 0.44
| geometric_albedo = 0.39 <ref>http://arxiv.org/pdf/1407.2245v1.pdf</ref>
| temperature = 2132°K
}}
{{Planetbox orbit
| period = 6.24658
| semimajor = 0.072 {{±|0.007|0.002}}
| eccentricity =
⚫ | inclination = 68.5 {{±|1.6|1}}
}}
{{Planetbox discovery
| discovery_date = 2013
| discoverers =
⚫ | discovery_method = ] (])
| detection_methods = Ellipsoidal light variations <br> Reflection/emission modulations
| discovery_status = Confirmed}}
{{Planetbox catalog
| names = KOI 2133.01
}}
{{Planetbox end}}


==Discovery and further confirmation==
⚫ '''Kepler-91b''' is a planet orbiting ], star slightly more massive than the ]. Kepler-91 has left the main sequence and is now a ] star.
⚫ 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 Kepler-91's low density, its shape is distorted to a slightly ellipsoidal shape due to gravitational effects of the planet. Ellipsoidal light variations caused by Kepler-91b constitute more than the third of the 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|s2cid= 118486056}}</ref>


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|s2cid=118665291}}</ref> However, the planetary nature was eventually confirmed again through both the radial velocity technique<ref>{{Cite journal|last1=Lillo-Box|first1=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|arxiv=1408.1528|s2cid=118424631}}</ref> and re-analysis of the light curve modulations.<ref>{{Cite journal|last1=Barclay|first1=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|arxiv=1408.3149|bibcode=2015ApJ...800...46B|s2cid=118528237}}</ref>
==Claims for discovery==

⚫ 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 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></ref>

Further analysis managed to question the planetary nature of the object. However, the planetary nature was eventually confirmed again. <ref name="arxiv">{{cite web|url=http://arxiv.org/abs/1401.1207|title=&#91;1401.1207&#93; A High False Positive Rate for Kepler Planetary Candidates of Giant Stars using Asterodensity Profiling|publisher=arxiv.org|accessdate=2014-01-20}}</ref>


==Characteristics== ==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&nbsp;days. Despite being one of the least edge-on orbits relative to Earth with inclination being about 68.5&nbsp;degrees, transit was detected due to low semi-major axis to host star radius ratio. 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&nbsp;million years.<ref name="Lillo-Box"/><ref name="Esteves"/>
Kepler-91b is expected to be engulfed by the parent star within about 55&nbsp;million years.<ref> J. Lillo-Box, D. Barrado, A. Moya, B. Montesinos, J. Montalbán, A. Bayo, M. Barbieri, C. Régulo, L. Mancini, H. Bouy, T. Henning: 14 Dec 2013</ref><ref>http://arxiv.org/abs/1407.2245 Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry] Lisa J. Esteves, Ernst J. W. De Mooij, Ray Jayawardhana: 10 Jul 2014</ref>


==Possible trojan companion==
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|s2cid=118366565}}</ref>


==References== ==References==
{{reflist}} {{reflist|refs=

⚫ }}


==External links== ==External links==
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] ]
] ]
] ]
]

]

{{extrasolar-planet-stub}}

Latest revision as of 21:58, 26 October 2024

Kepler-91b
Discovery
Discovery date2013
Detection methodTransit (Kepler Mission)
Orbital characteristics
Semi-major axis0.072+0.007
−0.002 AU
Orbital period (sidereal)6.24658 d
Inclination68.5+1.6
−1
StarKepler-91
Physical characteristics
Mean radius1.322+0.094
−0.086 RJ
Mass0.88+0.33
−0.17 MJ
Mean density0.44 g/cm (0.016 lb/cu in)
Albedo0.39
Temperature2132 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 confirmation

Kepler-91b was detected by analyzing the data of Kepler space telescope 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 Kepler-91's low density, its shape is distorted to a slightly ellipsoidal shape due to gravitational effects of the planet. Ellipsoidal light variations caused by Kepler-91b constitute more than the third of the 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

  1. ^ Esteves, Lisa J.; De Mooij, Ernst J. W.; Jayawardhana, Ray (2014). "Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry". The Astrophysical Journal. 804 (2): 150. arXiv:1407.2245. Bibcode:2015ApJ...804..150E. doi:10.1088/0004-637X/804/2/150. S2CID 117798959.
  2. ^ 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. S2CID 118486056.
  3. 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. S2CID 118665291.
  4. Lillo-Box, J.; Barrado, D.; Henning, Th.; Mancini, L.; Ciceri, S.; Figueira, P.; Santos, N. C.; Aceituno, J.; Sánchez, S. (August 2014). "Radial velocity confirmation of Kepler-91 b". Astronomy & Astrophysics. 568: L1. arXiv:1408.1528. doi:10.1051/0004-6361/201424587. ISSN 0004-6361. S2CID 118424631.
  5. 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. arXiv:1408.3149. Bibcode:2015ApJ...800...46B. doi:10.1088/0004-637X/800/1/46. ISSN 0004-637X. S2CID 118528237.
  6. 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. S2CID 118366565.

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