XO-4

{{distinguish|text=the OLPC XO-4 from the One Laptop per Child (OLPC) initiative or the Martin XO-4}}

{{Starbox begin

| name = XO-4 / Koit

}}

{{Starbox observe

| epoch = J2000

| constell = Lynx

| ra = {{RA|07|21|33.1602}}

| dec = {{DEC|+58|16|05.110}}

| appmag_v = 10.674 ± 0.019

}}

{{Starbox character

| class = F5V

| appmag_1_passband = B

| appmag_1 = 11.240 ± 0.029

| appmag_2_passband = V

| appmag_2 = 10.674 ± 0.019

| appmag_3_passband = J

| appmag_3 = 9.667 ± 0.021

| appmag_4_passband = H

| appmag_4 = 9.476 ± 0.022

| appmag_5_passband = K

| appmag_5 = 9.406 ± 0.023

}}

{{Starbox astrometry

| radial_v = {{val|1.74|0.33}}

| prop_mo_ra = {{val|−17.008|(12)}}

| prop_mo_dec = {{val|5.463|(12)}}

| pm_footnote =

| parallax = 3.7812

| p_error = 0.0156

| parallax_footnote =

| absmag_v =

}}

{{Starbox detail

| source =

| mass = {{val|1.32|0.02}}

| radius = {{val|1.56|0.05}}

| gravity = {{val|4.18|0.07}}

| luminosity =

| temperature = {{val|6397|70}}

| metal_fe = {{val|−0.04|0.03}}

| rotation =

| rotational_velocity = {{val|8.8|0.5}}

| age_gyr = {{val|2.1|0.6}}

}}

{{Starbox catalog

| names = {{odlist | name=Koit | 2MASS=J07213317+5816051 | GSC=03793-01994 | TIC=51234631 | TOI=1721 | TYC=3793-1994-1}}

}}

{{Starbox reference

| Simbad = XO-4

| NSTED = XO-4

}}

XO-4 is a star located approximately 863 light-years away from Earth in the Lynx constellation. It has a magnitude of about 11 and cannot be seen with the naked eye but is visible through a small telescope. A search for a binary companion star using adaptive optics at MMT Observatory was negative.

The star XO-4 is named Koit. The name was selected in the NameExoWorlds campaign by Estonia, during the 100th anniversary of the IAU. Koit is Estonian for dawn, and was named for a character in a folk tale written by Friedrich Robert Faehlmann.{{Cite web|url=http://www.nameexoworlds.iau.org/final-results|title=Approved names|website=NameExoworlds|language=en|access-date=2020-01-02}}{{Cite web|url=https://www.iau.org/news/pressreleases/detail/iau1912/|title=International Astronomical Union {{!}} IAU|website=www.iau.org|access-date=2020-01-02}}{{Cite web|url=https://estonianworld.com/knowledge/estonia-has-been-assigned-its-own-star-and-planet|title=Estonia has been assigned its own star and planet|website=Estonian World|date=20 January 2020|language=en|access-date=2020-01-20}}

Planetary system

One known exoplanet, XO-4b, which is classified as a hot Jupiter, orbits XO-4. This exoplanet was discovered in 2008 by the XO Project using the transit method. It has been named Hämarik, meaning dusk, and referring to a character from the same Faehlmann story featuring Koit.{{Cite web|url=https://estonianworld.com/knowledge/estonia-has-been-assigned-its-own-star-and-planet|title=Estonia has been assigned its own star and planet|website=Estonian World|date=20 January 2020|language=en|access-date=2020-01-20}} The planetary orbit is misaligned with the stellar rotation.

{{OrbitboxPlanet begin

| table_ref =

}}

{{OrbitboxPlanet

| exoplanet = b / Hämarik

| mass = {{val|1.612|0.027|0.028}}

| period = {{val|4.1250823|(39)}}

| semimajor = {{val|0.05524|0.00027|0.00028}}

| eccentricity = <0.0039

| inclination = {{val|88.7|1.1}}

| radius = {{val|1.34|0.05}}

}}

Notes

{{reflist|group="note"|refs=

{{refn|name="eccentricity"|group="note"|eccentricity approximately equal to zero is expected theoretically and is consistent with the radial velocities and secondary eclipse timing}}

}}

References

{{Reflist|refs=

{{cite web | url=http://vizier.u-strasbg.fr/viz-bin/VizieR-S?2MASS%20J07213317%2b5816051 | title=2MASS===07213317+5816051 | work=2MASS All-Sky Catalog of Point Sources | author=Cutri | display-authors=etal | year=2003 | access-date=2012-02-25 }}

{{cite journal | title=Adaptive Optics Images. II. 12 Kepler Objects of Interest and 15 Confirmed Transiting Planets | last1=Adams | first1=E. R. | last2=Dupree | first2=A. K. | last3=Kulesa | first3=C. | last4=McCarthy | first4=D. | display-authors=1 | journal=The Astronomical Journal | volume=146 | issue=1 | at=9 | year=2013 | arxiv=1305.6548 | bibcode=2013AJ....146....9A | doi=10.1088/0004-6256/146/1/9 | s2cid=119117620 }}

{{cite arXiv | title=XO-4b: An Extrasolar Planet Transiting an F5V Star | last1=McCullough | first1=P. R. | last2=Burke | first2=Christopher J. | last3=Valenti | first3=Jeff A. | last4=Long | first4=Doug | last5=Johns-Krull | first5=Christopher M. | last6=Machalek | first6=P. | last7=Janes | first7=K. A. | last8=Taylor | first8=B. | last9=Gregorio | first9=J. | display-authors=1 | year=2008 | class=astro-ph | eprint=0805.2921 }}

{{cite journal | title=The Rossiter-McLaughlin Effect of the Transiting Exoplanet XO-4b | url=https://academic.oup.com/pasj/article/62/6/L61/1501821 | last1=Narita | first1=Norio | last2=Hirano | first2=Teruyuki | last3=Sanchis-Ojeda | first3=Roberto | last4=Winn | first4=Joshua N. | last5=Holman | first5=Matthew J. | last6=Sato | first6=Bun'ei | last7=Aoki | first7=Wako | last8=Tamura | first8=Motohide | display-authors=1 | journal=Publications of the Astronomical Society of Japan | volume=62 | issue=6 | pages=L61–L65 | year=2010 | arxiv=1008.3803 | bibcode=2010PASJ...62L..61N | doi=10.1093/pasj/62.6.l61| s2cid=2967944 }}

{{cite web | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=TYC3793-1994-1 | title=SIMBAD query result: TYC 3793-1994-1 -- Star | publisher=Centre de Données astronomiques de Strasbourg | access-date=2009-04-26 }}

{{cite journal | title=Warm Spitzer Observations of Three Hot Exoplanets: XO-4b, HAT-P-6b, and HAT-P-8b | last1=Todorov | first1=Kamen O. | last2=Deming | first2=Drake | last3=Knutson | first3=Heather A. | last4=Burrows | first4=Adam | last5=Sada | first5=Pedro V. | last6=Cowan | first6=Nicolas B. | last7=Agol | first7=Eric | last8=Desert | first8=Jean-Michel | last9=Fortney | first9=Jonathan J. | display-authors=1 | journal=The Astrophysical Journal | volume=746 | issue=1 | at=111 | year=2012 | arxiv=1111.5858 | bibcode=2012ApJ...746..111T | doi=10.1088/0004-637X/746/1/111 | s2cid=119200344 }}

{{cite journal |last1=Bonomo |first1=A. S. |last2=Desidera |first2=S. |display-authors=etal |date=June 2017 |title=The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets |journal=Astronomy & Astrophysics |volume=602 |issue= |pages=A107 |doi=10.1051/0004-6361/201629882 |arxiv=1704.00373 |bibcode=2017A&A...602A.107B}}

}}

External links

{{cite web

| url=http://media4.obspm.fr/exoplanets/base/etoile.php?nom=XO-4

| title=XO-4

| work=Exoplanets

| access-date=2009-04-28

| archive-date=2016-03-03

| archive-url=https://web.archive.org/web/20160303233148/http://media4.obspm.fr/exoplanets/base/etoile.php?nom=XO-4

| url-status=dead

}}

Category:F-type main-sequence stars

Category:Lynx (constellation)

Category:Planetary transit variables

Category:Planetary systems with one confirmed planet

1721

51234631

Koit