K2-25

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K2-25
Close-up of K2-25 (noirlab2018l).jpg
K2-25 is the star at the center of this image.
Observation data
Epoch J2000       Equinox J2000
Constellation Taurus [1]
Right ascension 04h 13m 05.6131s [2]
Declination +15° 14′ 52.018″ [2]
Apparent magnitude  (V)15.881 [3]
Characteristics
Spectral type M4.5 V [4]
Apparent magnitude  (J)11.303(21) [5]
Apparent magnitude  (H)10.732(20) [5]
Apparent magnitude  (K)10.444(19) [5]
Variable type Planetary transit [4]
Astrometry
Radial velocity (Rv)38.64(15) [4]  km/s
Proper motion (μ)RA: 122.450(38)  mas/yr [2]
Dec.: −18.603(26)  mas/yr [2]
Parallax (π)22.3572 ± 0.0308  mas [2]
Distance 145.9 ± 0.2  ly
(44.73 ± 0.06  pc)
Details [6]
Mass 0.2634(77)  M☉
Radius 0.2932(93)  R☉
Luminosity 0.00816(29)  L☉
Temperature 3207(58)  K
Metallicity [Fe/H]0.15(3) [4]   dex
Rotation 1.87708(66) d [7]
Rotational velocity (v sin i)7.71(29) [8]  km/s
Age 650(70) [8] [9]   Myr
Other designations
vA 50, HAN 87, Gaia DR3  3311804515502788352, EPIC  210490365, 2MASS J04130560+1514520 [10] [11]
Database references
SIMBAD data

K2-25 is a young red dwarf star located in the Hyades cluster. There is a single known Neptune-sized planet in a 3.5 day orbit.

Contents

Hyades cluster

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. [12] Membership in the Hyades cluster was later confirmed. [13] [14] [4]

Properties

K2-25 is a red dwarf that is only 26% the mass of the Sun and less than 1% of the luminosity. [6] As a member of the Hyades cluster, it is only 650 million years old as compared to the Sun's 4.5 billion. [8]

There is clear evidence for starspot activity in both the Kepler data and radial velocities as well as the associated activity indicators. [15]

Planetary system

The star has one known planet, K2-25b, with searches of the Kepler space telescope data for transits of additional planets being negative. [4] Analysis of transit-timing variations from the Spitzer Space Telescope as well as the MEarth Project also found no evidence of additional planets. [16]

Discovery

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. [4] [10]

Characteristics

K2-25b is a Hot Neptune type planet in an eccentric 3.48 day orbit. [15]

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. [17]

The K2-25 planetary system [15]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
K2-25b24.5+5.7
−5.2  M🜨 		0.0287(12)3.48456408+0.0000006
−0.0000005		0.428+0.050
−0.049		88.16+0.18
−0.21 ° 		3.44(12)  R🜨
Location of K2-25 in the Hyades cluster Location of K2-25 (noirlab2018b).jpg
Location of K2-25 in the Hyades cluster

Related Research Articles

<span class="mw-page-title-main">Beehive Cluster</span> Open cluster in the constellation Cancer

The Beehive Cluster, is an open cluster in the constellation Cancer. One of the nearest open clusters to Earth, it contains a larger population of stars than other nearby bright open clusters holding around 1,000 stars. Under dark skies, the Beehive Cluster looks like a small nebulous object to the naked eye, and has been known since ancient times. Classical astronomer Ptolemy described it as a "nebulous mass in the breast of Cancer". It was among the first objects that Galileo studied with his telescope.

The Hungarian Automated Telescope Network (HATNet) project is a network of six small fully automated "HAT" telescopes. The scientific goal of the project is to detect and characterize extrasolar planets using the transit method. This network is used also to find and follow bright variable stars. The network is maintained by the Center for Astrophysics | Harvard & Smithsonian.

HAT-P-11, also designated GSC 03561-02092 and Kepler-3, is an orange dwarf metal rich star about 123 light-years away in the constellation Cygnus. This star is notable for its relatively large rate of proper motion. The magnitude of this star is about 9, which means it is not visible to the naked eye but can be seen with a medium-sized amateur telescope on a clear dark night. The age of this star is about 6.5 billion years.

<span class="mw-page-title-main">Ruprecht 147</span> Dispersed open cluster

Ruprecht 147 or NGC 6774 is a dispersed star cluster in the Milky Way galaxy. It is about 1,000 light years away, which is close to Earth in comparison with other such clusters. In late summer, it can be seen with binoculars in the constellation of Sagittarius. The stars, bound by gravity, are about 2.5 to 3.25 billion years old. The cluster, discovered in 1830 by John Herschel, was sometimes thought to be an asterism due to its sparseness and location against the background of the richest part of the Milky Way, and also since the brightest stars in this old cluster perished long ago. In 1966 the Czech astronomer Jaroslav Ruprecht classified it as a type III 2 m open cluster under the Trumpler scheme. It received otherwise little attention until 2012, when it was identified as a potentially important reference gauge for stellar and Galactic astrophysics research, particularly the research of Sun-like stars.

K2-3, also known as EPIC 201367065, is a red dwarf star with three known planets. It is on the borderline of being a late orange dwarf/K-type star, but because of its temperature, it is classified as a red dwarf.

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<span class="mw-page-title-main">HD 179070</span> Star in the constellation Lyra

HD 179070, also known as Kepler-21, is a star with a closely orbiting exoplanet in the northern constellation of Lyra. At an apparent visual magnitude of 8.25 this was the brightest star observed by the Kepler spacecraft to host a validated planet until the discovery of an exoplanet orbiting HD 212657 in 2018. This system is located at a distance of 354 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −18.2 km/s.

K2-19 is an early K-type or late G-type main sequence star that is magnetically active, and has a light curve that exhibits variations in brightness of ~1%. It is located approximately 976 light-years away in the constellation Virgo. Three confirmed transiting exoplanets are known to orbit this star.

K2-28 is a metal rich M4-type main sequence star. One confirmed transiting exoplanet is known to orbit this star. There is another star 5.2 arcseconds to the north–east of K2-28 however this star has a different proper motion and is therefore physically unrelated and probably a background star.

K2-32 is a G9-type main sequence star slightly smaller and less massive than the sun. Four confirmed transiting exoplanets are known to orbit this star. A study of atmospheric escape from the planet K2-32b caused by high-energy stellar irradiation indicates that the star has always been a very slow rotator.

K2-315b is an exoplanet located 185.3 light years away from Earth in the southern zodiac constellation Libra. It orbits the red dwarf K2-315.

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode: 1987PASP...99..695R . doi: 10.1086/132034 . Vizier query form
  2. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  3. ↑ Henden, A. A.; et al. (2016). "VizieR Online Data Catalog: AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)". VizieR On-line Data Catalog: II/336. Originally Published in: 2015AAS...22533616H. 2336. Bibcode:2016yCat.2336....0H. Vizier catalog entry
  4. 1 2 3 4 5 6 7 Mann, Andrew W.; et al. (2016). "Zodiacal Exoplanets in Time (ZEIT). I. A Neptune-sized Planet Orbiting an M4.5 Dwarf in the Hyades Star Cluster". The Astrophysical Journal. 818 (1) 46. arXiv: 1512.00483 . Bibcode: 2016ApJ...818...46M . doi: 10.3847/0004-637X/818/1/46 .
  5. 1 2 3 Skrutskie, M. F.; et al. (2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode: 2006AJ....131.1163S . doi: 10.1086/498708 . Vizier catalog entry
  6. 1 2 Thao, Pa Chia; et al. (2020). "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". The Astronomical Journal. 159 (1) 32. arXiv: 1911.05744 . Bibcode: 2020AJ....159...32T . doi: 10.3847/1538-3881/ab579b . S2CID   208006920.
  7. ↑ Mori, Mayuko; et al. (2024-04-05). "Characterization of starspots on a young M-dwarf K2-25: multi-band observations of stellar photometric variability and planetary transits". Monthly Notices of the Royal Astronomical Society. 530 (1): 167–189. arXiv: 2403.13946 . Bibcode: 2024MNRAS.530..167M . doi: 10.1093/mnras/stae841 .
  8. 1 2 3 Gaidos, E.; et al. (2020). "Zodiacal Exoplanets in Time. XI. The Orbit and Radiation Environment of the Young M Dwarf-Hosted Planet K2-25b". Monthly Notices of the Royal Astronomical Society: Letters. 498 (1). arXiv: 2007.12701 . Bibcode: 2020MNRAS.498L.119G . doi: 10.1093/mnrasl/slaa136 .
  9. ↑ Martín, Eduardo L.; et al. (2018). "The Lithium Depletion Boundary and the Age of the Hyades Cluster". The Astrophysical Journal. 856 (1) 40. arXiv: 1802.07155 . Bibcode: 2018ApJ...856...40M . doi: 10.3847/1538-4357/aaaeb8 .
  10. 1 2 David, Trevor J.; et al. (2016). "New Pleiades Eclipsing Binaries and a Hyades Transiting System Identified by K2". The Astronomical Journal. 151 (5) 112. arXiv: 1602.01901 . Bibcode: 2016AJ....151..112D . doi: 10.3847/0004-6256/151/5/112 .
  11. ↑ "K2-25". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2020-08-17.
  12. ↑ van Altena, W. F. (1966). "Low-luminosity members of the Hyades cluster". The Astronomical Journal. 71: 482–512. Bibcode: 1966AJ.....71..482V . doi:10.1086/109952.
  13. ↑ Röser, S.; et al. (2011). "A deep all-sky census of the Hyades". Astronomy & Astrophysics. 531: A92. arXiv: 1105.6093 . Bibcode: 2011A&A...531A..92R . doi: 10.1051/0004-6361/201116948 . Vizier catalog entry
  14. ↑ Douglas, S. T.; et al. (2014). "The Factory and the Beehive. II. Activity and Rotation in Praesepe and the Hyades". The Astrophysical Journal. 795 (2) 161. arXiv: 1409.7603 . Bibcode: 2014ApJ...795..161D . doi: 10.1088/0004-637X/795/2/161 .
  15. 1 2 3 Stefansson, Gudmundur; et al. (2020-09-30). "The Habitable Zone Planet Finder Reveals a High Mass and Low Obliquity for the Young Neptune K2-25b". The Astronomical Journal. 160 (4) 192. arXiv: 2007.12766 . Bibcode: 2020AJ....160..192S . doi: 10.3847/1538-3881/abb13a .
  16. ↑ Kain, Isabel J.; et al. (2020-03-01). "The Young Planetary System K2-25: Constraints on Companions and Starspots". The Astronomical Journal. 159 (3) 83. arXiv: 1912.05552 . Bibcode: 2020AJ....159...83K . doi: 10.3847/1538-3881/ab655b .
  17. ↑ Rockcliffe, Keighley E.; et al. (2021-09-01). "A Lyα Transit Left Undetected: the Environment and Atmospheric Behavior of K2-25b". The Astronomical Journal. 162 (3) 116. arXiv: 2109.04376 . Bibcode: 2021AJ....162..116R . doi: 10.3847/1538-3881/ac126f .
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