K2-25

Using proper motion measurements in a search for low-luminosity members of the Hyades cluster, William van Altena first identified the star vA 50 (later known as K2-25) as a probable cluster member. Membership in the Hyades cluster was later confirmed.

K2-25 is a red dwarf that is only 26% the mass of the Sun and less than 1% of the luminosity. As a member of the Hyades cluster, it is only 650 million years old as compared to the Sun's 4.5 billion.

There is clear evidence for starspot activity in both the Kepler data and radial velocities as well as the associated activity indicators.

The star has one known planet, K2-25b, with searches of the Kepler space telescope data for transits of additional planets being negative. Analysis of transit-timing variations from the Spitzer Space Telescope as well as the MEarth Project also found no evidence of additional planets.

Brightness measurements of K2-25 taken by the Kepler space telescope during its extended K2 mission led to the discovery of the transiting planet K2-25b.

K2-25b is a Hot Neptune type planet in an eccentric 3.48 day orbit.

Due to its proximity and the activity levels of its host star, K2-25b should be losing some of its atmosphere to space; however, observations of two transits by the Hubble Space Telescope to search for escaping neutral hydrogen were negative.

{{OrbitboxPlanet begin

| table_ref =

}}

{{OrbitboxPlanet

| exoplanet = K2-25b

| mass_earth = {{val|24.5|5.7|5.2}}

| semimajor = {{val|0.0287|(12)}}

| period = {{val|3.48456408|0.0000006|0.0000005}}

| eccentricity = {{val|0.428|0.050|0.049}}

| inclination = {{val|88.16|0.18|0.21}}

| radius_earth = {{val|3.44|(12)}}

}}

{{Orbitbox end}}

File:Location of K2-25 (noirlab2018b).jpg

{{reflist|refs=

{{cite journal | title=VizieR Online Data Catalog: AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016) | last1=Henden | first1=A. A. | last2=Templeton | first2=M. | last3=Terrell | first3=D. | last4=Smith | first4=T. C. | last5=Levine | first5=S. | last6=Welch | first6=D. | display-authors=1 | journal=VizieR On-line Data Catalog: II/336. Originally Published in: 2015AAS...22533616H | volume=2336 | year=2016 | bibcode=2016yCat.2336....0H }} [http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=II/336/apass9&recno=23691265 Vizier catalog entry ]

{{cite journal | title=New Pleiades Eclipsing Binaries and a Hyades Transiting System Identified by K2 | last1=David | first1=Trevor J. | last2=Conroy | first2=Kyle E.| last3=Hillenbrand | first3=Lynne A. | last4=Stassun | first4=Keivan G. | last5=Stauffer | first5=John | last6=Rebull | first6=Luisa M. | last7=Cody | first7=Ann Marie | last8=Isaacson | first8=Howard | last9=Howard | first9=Andrew W. | last10=Aigrain | first10=Suzanne | display-authors=1 | journal=The Astronomical Journal | volume=151 | issue=5 | article-number=112 | page= | date=2016 | arxiv=1602.01901 | bibcode=2016AJ....151..112D | bibcode-access=free | doi=10.3847/0004-6256/151/5/112 | doi-access=free }}

{{cite journal | title=The Factory and the Beehive. II. Activity and Rotation in Praesepe and the Hyades | last1=Douglas | first1=S. T. | last2=Agüeros | first2=M. A. | last3=Covey | first3=K. R. | last4=Bowsher | first4=E. C. | last5=Bochanski | first5=J. J. | last6=Cargile | first6=P. A. | last7=Kraus | first7=A. | last8=Law | first8=N. M. | last9=Lemonias | first9=J. J. | last10=Arce | first10=H. G. | last11=Fierroz | first11=D. F. | last12=Kundert | first12=A. | display-authors=1 | journal=The Astrophysical Journal | volume=795 | issue=2 | article-number=161 | page= | date=2014 | arxiv=1409.7603 | bibcode=2014ApJ...795..161D | bibcode-access=free | doi=10.1088/0004-637X/795/2/161 | doi-access=free }}

{{Cite Gaia DR3|3311804515502788352}}

{{cite journal | title=Zodiacal Exoplanets in Time. XI. The Orbit and Radiation Environment of the Young M Dwarf-Hosted Planet K2-25b | last1=Gaidos | first1=E. | last2=Hirano | first2=T. | last3=Wilson | first3=D. J. | last4=France | first4=K. | last5=Rockcliffe | first5=K. | last6=Newton | first6=E. | last7=Feiden | first7=G. | last8=Krishnamurthy | first8=V. | last9=Harakawa | first9=H. | last10=Hodapp | first10=K. W. | last11=Ishizuka | first11=M. | last12=Jacobson | first12=S. | last13=Konishi | first13=M. | last14=Kotani | first14=T. | last15=Kudo | first15=T. | last16=Kurokawa | first16=T. | last17=Kuzuhara | first17=M. | last18=Nishikawa | first18=J. | last19=Omiya | first19=M. | last20=Serizawa | first20=T. | last21=Tamura | first21=M. | last22=Ueda | first22=A. | last23=Vievard | first23=S. | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society: Letters | year=2020 | volume=498 | issue=1 | arxiv=2007.12701 | bibcode=2020MNRAS.498L.119G | bibcode-access=free | doi=10.1093/mnrasl/slaa136 | doi-access=free }}

{{cite journal | title=The Young Planetary System K2-25: Constraints on Companions and Starspots | last1=Kain | first1=Isabel J. | last2=Newton | first2=Elisabeth R. | last3=Dittmann | first3=Jason A. | last4=Irwin | first4=Jonathan M. | last5=Mann | first5=Andrew W. | last6=Thao | first6=Pa Chia | last7=Charbonneau | first7=David | last8=Winters | first8=Jennifer G. | display-authors=1 | journal=The Astronomical Journal | volume=159 | issue=3 | date=2020-03-01 | article-number=83 | page= | arxiv=1912.05552 | bibcode=2020AJ....159...83K | bibcode-access=free | doi=10.3847/1538-3881/ab655b | doi-access=free }}

{{cite journal | title=Zodiacal Exoplanets in Time (ZEIT). I. A Neptune-sized Planet Orbiting an M4.5 Dwarf in the Hyades Star Cluster | last1=Mann | first1=Andrew W. | last2=Gaidos | first2=Eric | last3=Mace | first3=Gregory N. | last4=Johnson | first4=Marshall C. | last5=Bowler | first5=Brendan P. | last6=LaCourse | first6=Daryll | last7=Jacobs | first7=Thomas L. | last8=Vanderburg | first8=Andrew | last9=Kraus | first9=Adam L. | last10=Kaplan | first10=Kyle F. | last11=Jaffe | first11=Daniel T. | display-authors=1 | journal=The Astrophysical Journal | volume=818 | issue=1 | article-number=46 | year=2016 | page= | arxiv=1512.00483 | bibcode=2016ApJ...818...46M | bibcode-access=free | doi=10.3847/0004-637X/818/1/46 | doi-access=free }}

{{cite journal | title=The Lithium Depletion Boundary and the Age of the Hyades Cluster | last1=Martín | first1=Eduardo L. | last2=Lodieu | first2=Nicolas | last3=Pavlenko | first3=Yakiv | last4=Béjar | first4=Víctor J. S. | display-authors=1 | journal=The Astrophysical Journal | volume=856 | issue=1 | article-number=40 | year=2018 | page= | arxiv=1802.07155 | bibcode=2018ApJ...856...40M | bibcode-access=free | doi=10.3847/1538-4357/aaaeb8 | doi-access=free }}

{{cite journal | title=Characterization of starspots on a young M-dwarf K2-25: multi-band observations of stellar photometric variability and planetary transits | last1=Mori | first1=Mayuko | last2=Ikuta | first2=Kai | last3=Fukui | first3=Akihiko | last4=Narita | first4=Norio | last5=de Leon | first5=Jerome P. | last6=Livingston | first6=John H. | last7=Ikoma | first7=Masahiro | last8=Kawai | first8=Yugo | last9=Kawauchi | first9=Kiyoe | last10=Murgas | first10=Felipe | last11=Palle | first11=Enric | last12=Parviainen | first12=Hannu | last13=Fernández Rodríguez | first13=Gareb | last14=Terada | first14=Yuka | last15=Watanabe | first15=Noriharu | last16=Tamura | first16=Motohide | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society | volume=530 | issue=1 | pages=167–189 | date=2024-04-05 | arxiv=2403.13946 | bibcode=2024MNRAS.530..167M | bibcode-access=free | doi=10.1093/mnras/stae841 | doi-access=free }}

{{cite journal | title=A Lyα Transit Left Undetected: the Environment and Atmospheric Behavior of K2-25b | last1=Rockcliffe | first1=Keighley E. | last2=Newton | first2=Elisabeth R. | last3=Youngblood | first3=Allison | last4=Bourrier | first4=Vincent | last5=Mann | first5=Andrew W. | last6=Berta-Thompson | first6=Zachory | last7=Agüeros | first7=Marcel A. | last8=Núñez | first8=Alejandro | last9=Charbonneau | first9=David | display-authors=1 | journal=The Astronomical Journal | volume=162 | issue=3 | date=2021-09-01 | article-number=116 | page= | arxiv=2109.04376 | bibcode=2021AJ....162..116R | bibcode-access=free | doi=10.3847/1538-3881/ac126f | doi-access=free }}

{{Cite constellation|K2-25}}

{{cite journal | title=A deep all-sky census of the Hyades | last1=Röser | first1=S. | last2=Schilbach | first2=E. | last3=Piskunov | first3=A. E. | last4=Kharchenko | first4=N. V. | last5=Scholz | first5=R.-D. | display-authors=1 | journal=Astronomy & Astrophysics | volume=531 | pages=A92 | date=2011 | arxiv=1105.6093 | bibcode=2011A&A...531A..92R | bibcode-access=free | doi=10.1051/0004-6361/201116948 | doi-access=free }} [https://vizier.cds.unistra.fr/viz-bin/VizieR-5?-ref=VIZ6513614754a2&-out.add=.&-source=J/A%2bA/531/A92/table1&recno=169 Vizier catalog entry ]

{{cite simbad | title=K2-25 | accessdate=2020-08-17 }}

{{cite journal | title=The Two Micron All Sky Survey (2MASS) | last1=Skrutskie | first1=M. F. | last2=Cutri | first2=R. M. | last3=Stiening | first3=R. | last4=Weinberg | first4=M. D. | last5=Schneider | first5=S. | last6=Carpenter | first6=J. M. | last7=Beichman | first7=C. | last8=Capps | first8=R. | last9=Chester | first9=T. | last10=Elias | first10=J. | last11=Huchra | first11=J. | last12=Liebert | first12=J. | last13=Lonsdale | first13=C. | last14=Monet | first14=D. G. | last15=Price | first15=S. | last16=Seitzer | first16=P. | last17=Jarrett | first17=T. | last18=Kirkpatrick | first18=J. D. | last19=Gizis | first19=J. E. | last20=Howard | first20=E | last21=Evans | first21=T | last22=Fowler | first22=J | last23=Fullmer | first23=L | last24=Hurt | first24=R | last25=Light | first25=R | last26=Kopan | first26=E. L. | last27=Marsh | first27=K. A. | last28=McCallon | first28=H. L. | last29=Tam | first29=R. | last30=Van Dyk | first30=S. | display-authors=1 | journal=The Astronomical Journal | volume=131 | issue=2 | pages=1163–1183 | year=2006 | bibcode=2006AJ....131.1163S | bibcode-access=free | doi=10.1086/498708 | doi-access=free }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ5f3a87d07d2c&-out.add=.&-source=II/246/out&2MASS===04130560%2b1514520 Vizier catalog entry ]

{{cite journal | title=The Habitable Zone Planet Finder Reveals a High Mass and Low Obliquity for the Young Neptune K2-25b | last1=Stefansson | first1=Gudmundur | last2=Mahadevan | first2=Suvrath | last3=Maney | first3=Marissa | last4=Ninan | first4=Joe P. | last5=Robertson | first5=Paul | last6=Rajagopal | first6=Jayadev | last7=Haase | first7=Flynn | last8=Allen | first8=Lori | last9=Ford | first9=Eric B. | last10=Winn | first10=Joshua | last11=Wolfgang | first11=Angie | last12=Dawson | first12=Rebekah I. | last13=Wisniewski | first13=John | last14=Bender | first14=Chad F. | last15=Cañas | first15=Caleb | last16=Cochran | first16=William | last17=Diddams | first17=Scott A. | last18=Fredrick | first18=Connor | last19=Halverson | first19=Samuel | last20=Hearty | first20=Fred | last21=Hebb | first21=Leslie | last22=Kanodia | first22=Shubham | last23=Levi | first23=Eric | last24=Metcalf | first24=Andrew J. | last25=Monson | first25=Andrew | last26=Ramsey | first26=Lawrence | last27=Roy | first27=Arpita | last28=Schwab | first28=Christian | last29=Terrien | first29=Ryan | last30=Wright | first30=Jason T. | display-authors=1 | journal=The Astronomical Journal | volume=160 | issue=4 | article-number=192 | page= | date=2020-09-30 | arxiv=2007.12766 | bibcode=2020AJ....160..192S | bibcode-access=free | doi=10.3847/1538-3881/abb13a | doi-access=free }}

{{cite journal | title=Zodiacal Exoplanets in Time (ZEIT). IX. A Flat Transmission Spectrum and a Highly Eccentric Orbit for the Young Neptune K2-25b as Revealed by Spitzer | last1=Thao | first1=Pa Chia | last2=Mann | first2=Andrew W. | last3=Johnson | first3=Marshall C. | last4=Newton | first4=Elisabeth R. | last5=Guo | first5=Xueying | last6=Kain | first6=Isabel J. | last7=Rizzuto | first7=Aaron C. | last8=Charbonneau | first8=David | last9=Dalba | first9=Paul A. | last10=Gaidos | first10=Eric | last11=Irwin | first11=Jonathan M. | last12=Kraus | first12=Adam L. | display-authors=1 | journal=The Astronomical Journal | volume=159 | issue=1 | article-number=32 | year=2020 | page= | arxiv=1911.05744 | bibcode=2020AJ....159...32T | bibcode-access=free | doi=10.3847/1538-3881/ab579b | doi-access=free | s2cid=208006920 }}

{{cite journal | last=van Altena | first=W. F. | title=Low-luminosity members of the Hyades cluster. | journal=The Astronomical Journal | volume=71 | pages=482–512 | date=1966 | bibcode=1966AJ.....71..482V | bibcode-access=free | doi=10.1086/109952 }}

}}

• [https://exoplanet.eu/catalog/k2_25_b--2519/ The Extrasolar Planets Encyclopaedia entry for K2-25b]

{{Taurus (constellation)}}

Category:Hyades (star cluster)

Category:M-type main-sequence stars

Category:Planetary systems with one confirmed planet

Category:Planetary transit variables

Category:Taurus (constellation)