PSR J0337+1715
{{Short description|Millisecond pulsar}}
{{Sky|03|37|43.82589|+|17|15|14.8280|4200}}
{{Starbox begin|name=PSR J0337+1715}}
{{Starbox observe|epoch=J2000.0|constell=Taurus|ra={{RA|03|37|43.82589}}|dec={{DEC|+17|15|14.8280}}|appmag_v=}}
{{Starbox character|class=Pulsar|b-v=|u-b=|variable=}}
{{Starbox detail|mass=|radius=|luminosity=|temperature=|metal=|rotation=|age_gyr=}}
{{Starbox catalog|names=PSR J0337+1715}}
{{Starbox reference|Simbad=PSR+J0337%2B1715}}
{{Starbox end}}
PSR J0337+1715 is a millisecond pulsar discovered in a Green Bank Telescope drift-scan survey from 2007. It is spinning nearly 366 times per second, 4200 light years away in the constellation Taurus. It is the first pulsar found in a stellar triple system. It is co-orbiting very closely with another star, a 0.2 solar-mass white dwarf, with a period of 1.6 days. There is a second white dwarf further out (within one astronomical unit) which is orbiting both the pulsar and the inner white dwarf, and has an orbit with a period of 327 days and a mass of 0.4 solar masses.{{Cite web | url=https://www.nbcnews.com/mach/science/einstein-s-theory-relativity-passes-its-toughest-test-yet-ncna889021 | title=Einstein's theory of relativity passes its toughest test yet| website=NBC News| date=5 July 2018}}{{cite journal |last1=Anne|first1=Archibald|author1-link= Anne Archibald |display-authors=etal|title=Universality of free fall from the orbital motion of a pulsar in a stellar triple system |journal=Nature |volume=559|issue=7712|pages=73–76|date=Jul 4, 2018 |doi=10.1038/s41586-018-0265-1|pmid=29973733|arxiv=1807.02059|bibcode=2018Natur.559...73A|s2cid=56322222 }} The fact that the pulsar is part of a triple system provides an opportunity to test the nature of gravity and the strong equivalence principle, with a sensitivity several orders of magnitude greater than before.{{Cite news|url=http://www.sci-news.com/astronomy/science-triple-star-nature-gravity-01664.html|title=Triple-Star System Can Give Clues to True Nature of Gravity {{!}} Astronomy {{!}} Sci-News.com|newspaper=Breaking Science News {{!}} Sci-News.com|language=en-US|access-date=2016-10-12}}{{Cite news|url=http://discovermagazine.com/2015/april/13-defying-gravity|title=Bold Experiments Will Put General Relativity to the Test {{!}} DiscoverMagazine.com|newspaper=Discover Magazine|access-date=2016-10-12}}{{Cite journal|last1=Ransom|first1=S. M.|last2=Stairs|first2=I. H.|last3=Archibald|first3=A. M.|author3-link= Anne Archibald |last4=Hessels|first4=J. W. T.|last5=Kaplan|first5=D. L.|last6=van Kerkwijk|first6=M. H.|last7=Boyles|first7=J.|last8=Deller|first8=A. T.|last9=Chatterjee|first9=S.|date=2014-01-01|title=A millisecond pulsar in a stellar triple system|journal=Nature|volume=505|issue=7484|pages=520–524|doi=10.1038/nature12917|issn=0028-0836|pmid=24390352|bibcode=2014Natur.505..520R|arxiv = 1401.0535 |s2cid=4468698 }}
Results were published in 2018 showing that if there is any departure from the equivalence principle it is no more than three parts per million{{cite journal |last1=Leah Crane |title=Einstein's theory passes triple-star test |journal=New Scientist |volume=239 |issue=3185 |pages=9 |date=Jul 7, 2018 |url=https://www.newscientist.com/article/mg23931853-900-trio-of-stars-shows-einstein-is-still-right-about-relativity/|bibcode=2018NewSc.239....9C |doi=10.1016/S0262-4079(18)31185-0 |s2cid=126337188 }}{{cite web |title=Scientists Test Einstein's Theory of Gravity on Unique Triple-Star System |url=http://www.sci-news.com/astronomy/einsteins-theory-gravity-triple-star-system-06170.html |website=Sci-News |date=Jul 5, 2018}} at 95% confidence level, improved to two parts per million in 2020.{{Cite journal|last1=Voisin|first1=G.|last2=Cognard|first2=I.|last3=Freire|first3=P. C. C.|last4=Wex|first4=N.|last5=Guillemot|first5=L.|last6=Desvignes|first6=G.|last7=Kramer|first7=M.|last8=Theureau|first8=G.|date=2020-06-01|title=An improved test of the strong equivalence principle with the pulsar in a triple star system|url=https://www.aanda.org/articles/aa/abs/2020/06/aa38104-20/aa38104-20.html|journal=Astronomy & Astrophysics|language=en|volume=638|pages=A24|arxiv=2005.01388|doi=10.1051/0004-6361/202038104|bibcode=2020A&A...638A..24V |s2cid=218486794 |issn=0004-6361}}
Planetary system
In 2022 evidence for a small planet with a mass comparable to that of the Moon on a wide orbit was found.{{cite arXiv |eprint=2205.09345 |class=astro-ph.HE |first1=Guillaume |last1=Voisin |first2=G. |last2=Luth |title=One pulsar, two white dwarfs, and a planet confirming the strong equivalence principle |last3=Cognard |first3=I. |last4=Freire |first4=P. |last5=Wex |first5=N. |last6=Guillemot |first6=L. |last7=Desvignes |first7=G. |last8=Kramer |first8=M. |last9=Theureau |first9=G. |last10=Saillenfest |first10=M. |year=2022}} [https://arxiv.org/pdf/2205.09345.pdf] In 2024, a study refined our knowledge of the planet's physical and orbital properties, finding that its mass is approximately {{val|0.0041|0.003|ul=Earth mass}}, or about 30% that of the Moon, making it one of the least massive known objects outside the Solar System. Its orbital parameters have been more thoroughly established, showing that it is on a slightly eccentric orbit lasting 3,310 days (or just over 9 years) which is also severely inclined relative to the plane of the triple system's orbit, suggesting it may have arrived there via influence from a Kozai mechanism.{{Citation |last1=Voisin |first1=Guillaume |title=Explanation of the exceptionally strong timing noise of PSR J0337+1715 by a circum-ternary planet and consequences for gravity tests |date=2025 |arxiv=2411.10066 |last2=Cognard |first2=Ismaël |last3=Saillenfest |first3=Melaine |last4=Tauris |first4=Thomas |last5=Wex |first5=Norbert |last6=Guillemot |first6=Lucas |last7=Theureau |first7=Gilles |last8=Freire |first8=P. C. C. |last9=Kramer |first9=Michael|journal=Astronomy & Astrophysics |volume=693 |pages=A143 |doi=10.1051/0004-6361/202452100 |bibcode=2025A&A...693A.143V }}
Since PSR J0337+1715 (AB) b's orbit is relatively stable (for at least 100 million years), it may possibly be the last surviving member of a population of small objects which were formed after the progenitor of the pulsar in this system became a red supergiant, engulfing one of the two other stars and creating a common envelope between it and said star. The engulfed star was slowed down from the common envelope gas, transferring its orbital energy to that gas, causing it to expand and be expelled from the star, settling into a circumbinary disk where many small objects condensed from this gas. Of those, only PSR J0337+1715 (AB) b is still present, as all the others were on less stable orbits which likely got them ejected from the system or crashing into one of the stars.
A 2025 study on the current pulsar planet candidates strongly suggests that PSR J0337+1715 (AB) b is not real, and is merely an artefact of "red noise", which is a product of variability within the pulsar in the system, and can manifest as quasiperiodic modulations in pulsar timing data, which can be falsely reported as planetary candidates.{{Cite journal |last1=Laycock |first1=Silas G. T. |last2=Christodoulou |first2=Dimitris M. |date=March 2025 |title=On the Number of Confirmed Pulsar Planets: The Rule of Six |journal=The Astrophysical Journal |language=en |volume=982 |issue=1 |pages=63 |doi=10.3847/1538-4357/adb1a8 |doi-access=free |issn=0004-637X}}
{{OrbitboxPlanet begin}}
{{OrbitboxPlanet hypothetical
| exoplanet = b
| mass =
| mass_earth = 0.0041
| semimajor = 5.52
| period = 3,310 days
| eccentricity = 0.257
| inclination = 119
| status = unconfirmed
}}{{End}}
References
{{Reflist}}
{{Stars of Taurus|state=collapsed}}
{{var-star-stub}}
Category:Taurus (constellation)