HD 139139
{{Short description|Star system in the constellation Libra}}
{{use dmy dates|date=July 2019}}
{{Starbox begin
| name = HD 139139
}}
{{Starbox image
| image = 250px
| caption = {{center|Star field around HD 139139
{{small|(north is up, field is approximately {{val|20|ul='}} wide)}}}}
}}
{{Starbox observe
| epoch = J2000
| constell = Libra
}}
{{Starbox character
| type =
| appmag_1_passband =
| appmag_1 =
| r-i =
| v-r =
| b-v =
| u-b =
| j-h =
| j-k =
}}
{{Starbox astrometry
| prop_mo_ra = {{val|-67.594}}
| prop_mo_dec = {{val|-92.516}}
| parallax = 9.2966
| p_error = 0.0472
| dist_ly =
| dist_pc =
| absmag_v =
}}
{{Starbox detail
| mass =
| luminosity_bolometric = 1.29
| rotation = {{val|14.5|ul=days}}
}}
{{Starbox catalog
| names = {{odlist |2MASS=J15370623−1908329 |BD=-18°4107 |GSC=06193-00969 |TYC=6193-969-1 |Gaia DR1=6254212216862625024 |Gaia DR2=6254212221163830016 |Gaia DR3=6254212221163830016 |DENIS=J153706.2−190832 |EPIC=249706694 |PPM=717808 |TIC=70652803}}, RAVE J153706.2−190833, USNO{{nbh}}B1.0 0708-00306171
}}
{{Starbox reference
| Simbad = HD+139139
}}
{{Starbox end}}
HD 139139 (also known as EPIC 249706694) is likely part of a bound pair system of main sequence stars about {{convert|350|ly|pc|abbr=off}} away from Earth in the constellation Libra. HD 139139 is a G-type main-sequence star, a little larger and more luminous than the Sun, and at an almost identical temperature. It has an apparent magnitude of 9.8. The companion star is thought to be a K5-K7 red dwarf {{val|3.3|ul=arcsec}} away from HD 139139. It is about three magnitudes fainter and has a temperature of between 4,100 and {{val|4,300|fmt=commas|ul=K}}. Both stars have a similar proper motion, meaning they may form a gravitationally-bound binary pair.
File:HD139139LightCurve.png for HD 139139 showing the irregularly spaced dimmings, adapted from Rappaport et al. (2019)]]
HD 139139 exhibits dips in brightness similar to those caused by transiting Earth-like planets. The Kepler space telescope observed 28 dips in their brightness over an 87-day period (23 August{{snd}}20 November 2017). The dips do not appear to be periodic as would be expected if they were due to transiting planets.
It is unknown which of the two stars produces the dimming events. Potential explanations that have been investigated include planets transiting a binary star, planets that are perturbing the orbits of each other producing large transit timing variations, a disintegrating planet, large dust producing asteroids, and short lived sunspots. According to Andrew Vanderburg, one of the researchers of the original studies,
:In astronomy we have a long history of not understanding something, thinking it’s aliens, and later finding out it’s something else ... The odds are pretty good that it’s going to be another one of those.
Subsequent observations performed with CHEOPS in two observing campaigns in the years 2021 and 2022 detected no transit-like events. The team estimated 4.8% probability of having missed all of them by chance, assuming that the frequency of the events remained unchanged from the 2017 measurements by Kepler. While it is possible that the events detected by Kepler were real, but inactive during observations by CHEOPS, the team also noted that it is not possible to discard also the possibility that they were caused by unidentified and infrequent instrumentation error.
Background
HD 139139 was identified as unusual by two independent groups of visual surveyors (citizen scientists) working in collaboration with professional astronomers.
: "But some of these patterns are too complex for computers to tease out; volunteer citizen scientists also comb through the Kepler catalogue, using the human brain's power to uncover surprising signals. In spring 2018 some of these citizen astronomers contacted Vanderburg and told him to check out HD 139139, a sunlike star roughly 350 light-years away."
HD 139139 is one of the 0.5% of stars in the sky that can see Earth transit, according to Andrew Vanderburg. "The transit impact parameter would be close to 0.9, so they can just barely see us – the transit duration would be only about 40% the duration we'd expect for a perfectly edge-on transit."
See also
References
{{reflist|30em|refs=
{{cite Gaia DR2|6254212221163830016}}
{{cite AV media |last1=Godier |first1=John Michael |last2=Andrew |first2=Vanderburg |medium=video {{small| 30{{sup|m}}36{{sup|s}} }} |title=The mysterious star HD 139139 with Dr. Andrew Vanderburg |url=https://www.youtube.com/watch?v=Ml8BsjSdPWo&t=1492 |website=YouTube |access-date=13 July 2019}}
{{cite news |last=Crane |first=Leah |title=The weirdest stars we've ever seen have astronomers utterly baffled |date=2 July 2019 |magazine=New Scientist |url=https://www.newscientist.com/article/2208275-the-weirdest-stars-weve-ever-seen-have-astronomers-utterly-baffled/ |access-date=4 July 2019 }}
{{cite news |last=Yirka |first=Bob |date=3 July 2019 |title=Binary stars with unexplainable dimming pattern |website=Phys.org |url=https://phys.org/news/2019-07-binary-stars-unexplainable-dimming-pattern.html |access-date=4 July 2019 }}
{{cite journal |last1=Rappaport |first1=S. |last2=Vanderburg |first2=A. |last3=Kristiansen |first3=M.H. |last4=Omohundro |first4=M. R. |last5=Schwengeler |first5=H.M. |last6=Terentev |first6=I.A. |last7=Dai |first7=F. |last8=Masuda |first8=K. |last9=Jacobs |first9=T.L. |last10=Lacourse |first10=D. |last11=Latham |first11=D.W. |last12=Bieryla |first12=A. |last13=Hedges |first13=C.L. |last14=Dittmann |first14=J. |last15=Barentsen |first15=G. |last16=Cochran |first16=W. |last17=Endl |first17=M. |last18=Jenkins |first18=J.M. |last19=Mann |first19=A. |display-authors=6 |year=2019 |title=The Random Transiter – EPIC 249706694/HD 139139 |journal=Monthly Notices of the Royal Astronomical Society |volume=488 |issue=2 |pages=2455–2465 |arxiv=1906.11268 |doi=10.1093/mnras/stz1772 |doi-access=free |bibcode=2019MNRAS.488.2455R |s2cid=195699431 }}
{{cite magazine |last=Mann |first=Adam |title=Astronomers don't know what to make of this incredibly bizarre star |magazine=Scientific American |url=https://www.scientificamerican.com/article/astronomers-dont-know-what-to-make-of-this-incredibly-bizarre-star/ |access-date=3 July 2019}}
{{cite web |last=Schirmer |first=H. |title=Why the 'Random Transiter' (HD139139) is now the most mysterious star in the Galaxy |date=30 June 2019 |website=Reddit |url=https://www.reddit.com/r/KIC8462852/comments/c70xw2/why_the_random_transiter_hd139139_is_now_the_most/ |access-date=19 July 2019 }}
{{cite web |title=Basic data: HD 139139 – high proper-motion star |year=2019 |website=SIMBAD |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD_139139 |access-date=7 July 2019 }}
{{cite web |title=K2 search results – EPIC 249706694 |year=2019 |website=Space Telescope Science Institute (STScI.edu) |url=http://archive.stsci.edu/k2/data_search/search.php?ktc_k2_id=249706694&action=Search |access-date=5 July 2019 }}
{{cite journal |last1=Høg |first1=E. |last2= Fabricius |first2= C. |last3=Makarov |first3=V.V. |last4=Urban |first4=S. |last5=Corbin |first5=T. |last6=Wycoff |first6=G. |last7=Bastian |first7=U. |last8=Schwekendiek |first8=P. |last9=Wicenec |first9=A. |display-authors=6 |year=2000 |title=The Tycho 2 catalogue of the 2.5 million brightest stars |journal=Astronomy and Astrophysics |volume=355 |page=L27 |bibcode=2000A&A...355L..27H }}
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}}
External links
- {{cite web |title=EPIC Catalog at MAST |website=Space Telescope Science Institute (stsci.edu) |url=http://archive.stsci.edu/k2/epic/search.php }}
- {{YouTube|FPcKs3bC-1I | HD 139139 summary & related (video {{small| 8{{sup|m}}57{{sup|s}} }}) }}
- {{YouTube|Ml8BsjSdPWo | The mysterious star HD 139139 with Dr. Andrew Vanderburg (video {{small| 30{{sup|m}}36{{sup|s}} }}) }}
- {{cite AV media |title=HD 139139 summary |website=kgw.com |medium=video {{small| 1{{sup|m}}00{{sup|s}} }} |url=https://www.kgw.com/video/tech/science/amaze-lab/a-stars-unpredictable-dimming-pattern-is-stumping-scientists/609-fb765204-e679-4251-a83c-0ad4b65aad82 |access-date=4 July 2019 |archive-date=4 July 2019 |archive-url=https://web.archive.org/web/20190704130729/https://www.kgw.com/video/tech/science/amaze-lab/a-stars-unpredictable-dimming-pattern-is-stumping-scientists/609-fb765204-e679-4251-a83c-0ad4b65aad82 |url-status=dead }}
{{Stars of Libra|state=collapsed}}
{{Sky|15|37|06.215|-|19|08|33.09|350}}
{{Portal bar|Astronomy|Space}}
{{DEFAULTSORT:HD 139139}}
Category:G-type main-sequence stars