PSR J0740+6620

PSR J0740+6620 is a neutron star in a binary system with a white dwarf, located 4,600 light years away in the Milky Way galaxy. It was discovered in 2019, by astronomers using the Green Bank Telescope in West Virginia, U.S., and confirmed as a rapidly rotating millisecond pulsar.

PSR J0740+6620

Schematic of a pulsar
Observation data Epoch J2000      Equinox J2000
Constellation	Camelopardalis
Right ascension	07h 40m 45.799s[1]
Declination	+66° 20′ 33.60″[1]
Characteristics
Evolutionary stage	Pulsar
Details
Mass	2.08 M☉
Radius	13-15.1 km
Other designations
3FGL J0740.8+6621, 4FGL J0741.0+6618
Database references
SIMBAD	data

It is among the most massive neutron stars ever observed – with 2.08+0.07
−0.07 M_☉^[2][3][4] placing it near the boundary of the theoretical maximum.^[5] Its mass was calculated via the Shapiro delay of its white dwarf companion as it passed edge-on to Earth. It was the record holder for the heaviest NS until July 2022 when the title was taken by PSR J0952–0607 with a reported mass of 2.35+0.17
−0.17 M_☉.^[6][7]

PSR J0740+6620 is estimated to measure 12.39+1.30
−0.98 km (7.70+0.81
−0.61 mi).^[8][9][10]

See also

• PSR B1913+16
• PSR B1957+20 (1.66-2.4 M_☉)
• Neutron Star Interior Composition Explorer (NICER)
• List of the most massive neutron stars