PSR B1257+12 c

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**PSR B1257+12 c**
Parent star
Extrasolar planet		List of extrasolar planets
Star		PSR B1257+12
Constellation		Virgo
Right ascension	(α)	13^h 00^m 01^s
Declination	(δ)	+12° 40′ 57″
Distance		980 ly (300 pc)
Spectral type		Pulsar
Orbital elements
Semimajor axis	(a)	0.36 AU
Eccentricity	(e)	0.0186 ± 0.0002
Orbital period	(P)	66.5419 ± 0.0001 d
Angular distance	(θ)	1.2 mas
Longitude of periastron	(ω)	250.4 ± 0.6°
Time of periastron	(T₀)	2,449,768.1 ± 0.1 JD
Semi-amplitude	(K)	? m/s
Physical characteristics
Mass	(m)	0.013 M_J (4.3 ± 0.2 M_⊕)
Discovery information
Discovery date		22 January 1992
Discoverer(s)		Aleksander Wolszczan
Detection method		Pulsar Timing
Discovery site		Poland
Discovery status		Published

PSR B1257+12 c, previously known as PSR B1257+12 B, is the second planet orbiting the pulsar at a distance of 0.36 AU with an orbital period of approximately 66 days. The planet is over four times as massive as the Earth. Because planet B and planet C orbit rather close to each other, they cause measurable perturbations in each other's orbits. As expected, perturbations were detected confirming that the planets are real. Accurate masses of the two planets, as well as their inclinations, were measured by calculating how much the planets interfere each other.