View source for Astronomy:PSR J1903+0327

{{Short description|Pulsar in the constellation Aquila}}
'''PSR J1903+0327''' is a millisecond [[Astronomy:Pulsar|pulsar]] in a highly eccentric binary orbit.<ref>{{Cite journal |last1=Champion |first1=David J. |last2=Ransom |first2=S. M. |last3=Lazarus |first3=P. |last4=Camilo |first4=F. |last5=Bassa |first5=C. |last6=Kaspi |first6=V. M. |author6-link=Victoria Kaspi|last7=Nice |first7=D. J. |last8=Freire |first8=P. C. C. |last9=Stairs |first9=I. H. |last10=Van Leeuwen |first10=J. |last11=Stappers |first11=B. W. |last12=Cordes |first12=J. M. |last13=Hessels |first13=J. W. T. |last14=Lorimer |first14=D. R. |last15=Arzoumanian |first15=Z. |last16=Backer |first16=D. C. |last17=Bhat |first17=N. D. R. |last18=Chatterjee |first18=S. |last19=Cognard |first19=I. |last20=Deneva |first20=J. S. |last21=Faucher-Giguere |first21=C.-A. |last22=Gaensler |first22=B. M. |last23=Han |first23=J. |last24=Jenet |first24=F. A. |last25=Kasian |first25=L. |last26=Kondratiev |first26=V. I. |last27=Kramer |first27=M. |last28=Lazio |first28=J. |last29=McLaughlin |first29=M. A. |last30=Venkataraman |first30=A. |title=An Eccentric Binary Millisecond Pulsar in the Galactic Plane |journal=Science |date=2008 |volume=320 |issue=5881 |pages=1309–1312 |doi=10.1126/science.1157580 |pmid=18483399|bibcode = 2008Sci...320.1309C |arxiv = 0805.2396 |s2cid=6070830 |display-authors=8 }}</ref>
 
The pulsar was discovered in an ongoing L-band (1.4&nbsp;GHz) survey with the 305 m diameter [[Astronomy:Arecibo Observatory|Arecibo radio telescope]].<ref>{{Cite journal |first1=J. M. |last1=Cordes |last2=Freire |first2=P. C. C.|last3=Lorimer |first3=D. R. |last4=Camilo |first4=F. |last5=Champion |first5=D. J. |last6=Nice |first6=D. J. |last7=Ramachandran |first7=R. |last8=Hessels |first8=J. W. T. |last9=Vlemmings |first9=W. |last10=Van Leeuwen |first10=J. |last11=Ransom |first11=S. M. |last12=Bhat |first12=N. D. R. |last13=Arzoumanian |first13=Z. |last14=McLaughlin |first14=M. A. |last15=Kaspi |first15=V. M. |last16=Kasian |first16=L. |last17=Deneva |first17=J. S. |last18=Reid |first18=B. |last19=Chatterjee |first19=S. |last20=Han |first20=J. L. |last21=Backer |first21=D. C. |last22=Stairs |first22=I. H. |last23=Deshpande |first23=A. A. |last24=Faucher-Giguere |first24=C.-A. |title=Arecibo Pulsar Survey Using ALFA. I. Survey Strategy and First Discoveries  |journal=Astrophys. J. |volume=637 |issue=1 |pages=446–455 |date=2006 |doi=10.1086/498335 |arxiv = astro-ph/0509732 |bibcode = 2006ApJ...637..446C |s2cid=55390845 |display-authors=8 }}</ref>

The pulse period is 2.15 ms, or 465.1 times per second.  Analysis of the pulse timing residuals shows a binary [[Physics:Orbit|orbit]] with a period of 95.17 days, and a high [[Astronomy:Orbital eccentricity|eccentricity]], ''e'' = 0.437.  The mass of the companion is ~1 solar mass ({{Solar mass|link=y}}), while the pulsar mass is unusually large at 1.67 ± 0.02 {{Solar mass}};<ref>{{Cite journal |first1=P. C. C. |last1=Freire | last2=Bassa |first2=C. G. |last3 = Wex |first3 = N. | last4 =Stairs | first4=I. H. | last5=Champion | first5=D. J. | last6=Ransom | first6=S. M. | last7=Lazarus | first7=P. | last8=Kaspi | first8=V. M. | author8-link=Victoria Kaspi | last9=Hessels | first9=J. W. T. |last10=Kramer |first10=M. |last11=Cordes |first11=J. M. |last12=Verbiest |first12=J. P. W. |last13=Podsiadlowski |first13=P. |last14=Nice |first14=D. J. |last15=Deneva |first15=J. S. |last16=Lorimer |first16=D. R. |last17=Stappers |first17=B. W. |last18=McLaughlin |first18=M. A. |last19=Camilo |first19=F. |title=On the nature and evolution of the unique binary pulsar J1903+0327  |journal=[[Organization:Monthly Notices of the Royal Astronomical Society|Monthly Notices of the Royal Astronomical Society]] |volume=412 |issue=4 |pages=2763 |date=2011 |doi=10.1111/j.1365-2966.2010.18109.x |arxiv = 1011.5809 |bibcode = 2011MNRAS.412.2763F|s2cid=67841433 |display-authors=8 }}</ref> the third largest precisely measured mass after those of [[Astronomy:PSR J1614−2230|PSR J1614−2230]] and [[Astronomy:PSR J0348+0432|PSR J0348+0432]].  A near-infrared companion, K<sub>S</sub> = 18 (2.22µ), is observed in Gemini North images at its radio position, in 2011 radial velocity measurements made with the [[Astronomy:Very Large Telescope|VLT]] confirmed this to be the companion to the millisecond pulsar; the first such system to be observed in the Galaxy.

Popular theories for the formation of binary millisecond pulsars require mass transfer onto the rotating neutron star from a [[Astronomy:White dwarf|white dwarf]] companion in order to spin it up to periods less than about 10 ms—a process expected to be accompanied by strong tidal forces, producing a highly circular orbit. The main-sequence companion and the eccentric orbit of PSR J1903+0327 do not conform to this expectation. The system is likely to have originated as a triple system. The remnant of the star that transferred mass to the neutron star (its original close companion) was later ejected by a gravitational interaction with the unevolved third member of the system; its present main-sequence companion.

==References==
{{Reflist}}

{{Stars of Aquila}}

{{DEFAULTSORT:PSR J1903+0327}}
[[Category:Aquila (constellation)]]
[[Category:Binary stars]]
[[Category:Pulsars]]



{{Sourceattribution|PSR J1903+0327}}