PSR J0952–0607

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PSR J0952–0607

PSR J0952–0607 (center crosshair) imaged by the Fermi Gamma-ray Space Telescope
Observation data
J2000.0
Constellation Sextans
Right ascension 09h 52m 08.319s[1]
Declination −06° 07′ 23.49″[1]
Characteristics
Spectral type Pulsar
Apparent magnitude (i) 22.0–24.4[2]
Distance
970+1160
−530 pc[3]
or 1740+1570
−820 pc[3]
or 6260+360
−400 (optical) pc[4]
Details
PSR J0952–0607 A
dex
Inclination (i)
59.8+2.0
−1.9[4]°
Semi-amplitude (K2)
(secondary)		376.1±5.1[4] km/s
Other designations
PSR J0952–0607, 4FGL J0952.1–0607
Database references
SIMBADdata

PSR J0952–0607 is a massive

constellation Sextans.[5] It holds the record for being the most massive neutron star known as of 2022, with a mass 2.35±0.17 times as much as the Sun—potentially close to the Tolman–Oppenheimer–Volkoff mass upper limit for neutron stars.[4][6] The pulsar rotates at a frequency of 707 Hz (1.41 ms period), making it the second-fastest-spinning pulsar known, and the fastest-spinning pulsar known within the Milky Way.[7][5]

PSR J0952–0607 was discovered by the

gamma-ray and X-ray wavelengths.[9][3][10]

Discovery

PSR J0952–0607 was first identified as an unassociated

The Astrophysical Journal Letters and was announced in a NASA press release in September 2017.[7][5]

Distance and location

The distance of PSR J0952–0607 from Earth is highly uncertain.[2][3][4]

Binary system

The PSR J0952–0607

accretes some of the companion's lost material onto itself.[8]: 127 [4]
: 1 

Companion

Artist's impression of a black widow pulsar system, where a stellar-mass companion is being ablated by the intense radiation of its host pulsar

The companion orbits the pulsar at a distance of 1.6 million km (1 million mi)

tidally locked, with one hemisphere always facing the pulsar.[3]: 8  The companion does not appear to eclipse the pulsar,[7]: 1 [3]: 12  indicating that its orbit is oriented nearly face-on with an inclination of 60° with respect to the plane perpendicular to Earth's line of sight.[4]: 4  The companion's orbital motion also does not appear to modulate the pulsar's pulsations, signifying a circular orbit with negligible orbital eccentricity.[3]
: 4 

The companion was likely a former star that had been reduced to the size of a large gas giant planet or brown dwarf,[6][3]: 12  with a present-day mass of 0.032±0.002 M☉ or 34±2 MJ according to radial velocity measurements.[4]: 4  Due to intense irradiation and heating by the host pulsar, the companion's radius is bloated up to 80% of its Roche lobe[3]: 8 [4]: 4  and brightly glows with a thermal luminosity of about 10 L☉,[a] thereby accounting for much of the system's optical brightness.[4]: 1, 4 [2]: 1  As a result of bloating, the companion attains a low density likely around 10 g/cm3 (with significant uncertainty due to the system's unknown distance from Earth),[2]: 11  making it susceptible to tidal deformation by the pulsar.[3]: 12 

The companion's pulsar-facing irradiated hemisphere is continuously heated up to a temperature of 6,200 K, whereas the companion's unirradiated hemisphere experiences a uniform[2]: 4  temperature of 3,000 K.[4]: 4  This hemispherical temperature difference corresponds to a difference in hemisphere luminosities, which in turn causes significant variability in apparent brightness as the companion rotates around the pulsar.[7]: 4 [3]: 8  This brightness variability is demonstrated in PSR J0952–0607's optical light curve, which exhibits an amplitude greater than one magnitude.[2]: 4 

Mass

PSR J0952–0607 has a mass of 2.35±0.17 M☉, making it the most massive neutron star known as of 2022.[4] The pulsar likely acquired most of its mass by accreting up to 1 M☉ of lost material from its companion.[4]: 5 

Rotation and age

PSR J0952–0607 rotates at a frequency of 707

characteristic age of 4.9 billion years.[3]
: 11 

Magnetic field

Measurements of PSR J0952–0607's spin-down rate show that the pulsar has a remarkably weak surface magnetic field strength of 6.1×107 gauss (6.1×103 T), placing it among the 10 weakest pulsar magnetic fields known as of 2022.[4]: 1  For context, ordinary pulsar magnetic fields usually lie on the order of teragauss (1×1012 G, 1.0×108 T), over 10,000 times greater than that of PSR J0952–0607.[13][4]: 1  Other millisecond pulsars exhibit similarly weak magnetic fields, hinting at a common albeit unknown mechanism in these types of systems;[3]: 2  possible explanations range from accreted matter burying the pulsar's surface magnetic field to heat-driven evolution of the pulsar's solid crust.[13]: 1–2 [4]: 1 

Gamma-ray emissions

PSR J0952–0607 appears very faint in gamma-rays and was not detected in July 2011.[10][3]: 2 

See also

Notes

  1. ^ a b Luminosity converted from erg/s to L☉, given 3.81+0.46
    −0.43    ×1034 erg/s     from Romani et al. (2022)[4] and the solar luminosity L☉ = 3.826×1033 erg/s.
  2. ^
    Kepler's Third Law
    : given primary mass = 2.35 M☉ and orbital period = 6.42 h.
    light seconds (18787 km) from gamma-ray and radio pulsation timing.[3]
    : 6 

References

  1. ^ a b "PSR J0952-0607 -- Pulsar". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 26 July 2022.
  2. ^
    doi:10.3847/1538-4357/ab378b
    . 108.
  3. ^
    doi:10.3847/1538-4357/ab357e
    . 42.
  4. ^
    doi:10.3847/2041-8213/ac8007
    . L18.
  5. ^ a b c d e Reddy, Francis (5 September 2017). "'Extreme' Telescopes Find the Second-fastest-spinning Pulsar". NASA. Retrieved 26 July 2022.
  6. ^ a b c Sanders, Robert (26 July 2022). "Heaviest neutron star to date is a 'black widow' eating its mate". Berkeley News. University of California Berkeley. Retrieved 26 July 2022.
  7. ^
    doi:10.3847/2041-8213/aa8400
    . L20.
  8. ^
    doi:10.1017/S174392131202337X
    .
  9. doi:10.3847/1538-4357/ab3578
    . 128.
  10. ^
    Bibcode:2019nova.pres.6048K
    . Retrieved 26 July 2022.
  11. doi:10.3847/1538-4365/ab6bcb
    . 33.
  12. ^ Starr, Michelle (24 September 2019). "Astronomers Detect Gamma Rays From an Extreme Pulsar Spinning 707 Times Per Second". ScienceAlert. Retrieved 27 July 2022.
  13. ^
    hdl:1885/247814
    . 48.
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