Black Widow Pulsar Explained

The Black Widow Pulsar (PSR B1957+20) is an eclipsing binary millisecond pulsar in the Milky Way. Discovered in 1988, it is located roughly 6500abbr=offNaNabbr=off away from Earth. It orbits with a brown dwarf or Super-Jupiter companion with a period of 9.2 hours with an eclipse duration of approximately 20 minutes. When it was discovered, it was the first such pulsar known.[1] The prevailing theoretical explanation for the system implied that the companion is being destroyed by the strong powerful outflows, or winds, of high-energy particles caused by the neutron star; thus, the sobriquet black widow was applied to the object. Subsequent to this, other objects with similar features have been discovered, and the name has been applied to the class of millisecond pulsars with an ablating companion, as of February 2023 around 41 black widows are known to exist.[2] [3]

Later observations of the object showed a bow shock in H-alpha and a smaller-in-extent shock seen in X-rays (as observed by the Chandra X-ray Observatory), indicating a forward velocity of approximately a million kilometers per hour.[4]

In 2010, it was estimated that the neutron star's mass was at least

1.66M\odot

and possibly as high as

2.4M\odot

(the latter of which, if true, would surpass PSR J0740+6620 for the title of most massive neutron star yet detected and place it within range of the Tolman–Oppenheimer–Volkoff limit).[5] In January 2023 the upper limit was revised down to

1.8M\odot

[6] [7]

Planets

The pulsar has a substellar companion, possibly a brown dwarf.

Gallery

Artist impressions of the Black Widow Pulsar.

See also

Notes and References

  1. Fruchter . A. S. . Stinebring . D. R. . Taylor . J. H. . May 19, 1988 . A millisecond pulsar in an eclipsing binary . . 333 . 6170 . 237–9 . 1988Natur.333..237F . 10.1038/333237a0 . 4337525.
  2. Swihart . Samuel J. . Strader . Jay . Chomiuk . Laura . Aydi . Elias . Sokolovsky . Kirill V. . Ray . Paul S. . Kerr . Matthew . 2022-12-01 . A New Flaring Black Widow Candidate and Demographics of Black Widow Millisecond Pulsars in the Galactic Field . The Astrophysical Journal . 941 . 2 . 199 . 10.3847/1538-4357/aca2ac . 2210.16295 . 2022ApJ...941..199S . 253224234 . 0004-637X . free .
  3. Web site: Cassese . Ben . 2023-02-17 . A New Spider Joins a Deadly Club . 2023-02-18 . AAS Nova . en-US.
  4. Web site: Chandra Digest . February 27, 2003 . B1957+20: A Cocoon Found Inside the Black Widow's Web . June 4, 2022 . Chandra X-Ray Observatory.
  5. Van Kerkwijk . M. H. . Breton . R. P. . Kulkarni . S. R. . 2011 . Evidence for a Massive Neutron Star from a Radial-Velocity Study of the Companion to the Black-Widow Pulsar Psr B1957+20 . . 728 . 2 . 95 . 1009.5427 . 2011ApJ...728...95V . 10.1088/0004-637X/728/2/95 . 37759376.
  6. Clark . C. J. . Kerr . M. . Barr . E. D. . Bhattacharyya . B. . Breton . R. P. . Bruel . P. . Camilo . F. . Chen . W. . Cognard . I. . Cromartie . H. T. . Deneva . J. . Dhillon . V. S. . Guillemot . L. . Kennedy . M. R. . Kramer . M. . 2023-01-26 . Neutron star mass estimates from gamma-ray eclipses in spider millisecond pulsar binaries . Nature Astronomy . 7 . 4 . en . 451–462 . 10.1038/s41550-022-01874-x . 37096051 . 10119022 . 2301.10995 . 2023NatAs...7..451C . 256274563 . 2397-3366.
  7. Web site: Gamma-ray eclipses shed new light on spider pulsars . 2023-01-27 . www.aei.mpg.de . en.

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