PSR B1257+12 b, alternatively designated PSR B1257+12 A, also named Draugr, is an
extrasolar planet approximately away
in the
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The first constellati ...
of
Virgo. The planet is the innermost object orbiting the
pulsar Lich, making it a
pulsar planet in the dead stellar system. It is about twice as massive as the
Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
, and is listed as the
least massive planet (with the mass accurately determined) known, including among the planets in the
Solar System.
Nomenclature
The convention that arose for designating pulsars was that of using the letters PSR (Pulsating Source of Radio) followed by the pulsar's
right ascension and degrees of
declination
In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. The declination angle is measured north (positive) or ...
. The modern convention prefixes the older numbers with a B meaning the coordinates are for the 1950.0
epoch. All new pulsars have a J indicating 2000.0 coordinates and also have declination including minutes. Pulsars that were discovered before 1993 tend to retain their B names rather than use their J names, but all pulsars have a J name that provides more precise coordinates of its location in the sky.
On its discovery, the planet was designated PSR 1257+12 A and later PSR B1257+12 b. It was discovered before the convention that extrasolar planets receive designations consisting of the star's name followed by lower-case
Roman letters starting from "b" was established.
However, it is listed under the latter convention on astronomical databases such as
SIMBAD and the
Extrasolar Planets Encyclopedia. Hence the designation PSR B1257+12 b.
In July 2014, the
International Astronomical Union launched
NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name was Draugr for this planet. The winning name was submitted by the Planetarium Südtirol Alto Adige in
Karneid,
Italy
Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
.
Draugr are
undead creatures in
Norse mythology.
See also
*
List of exoplanets discovered before 2000 - PSR B1257+12 b
References
*
External links
*
Pulsar Planets
{{Sky, 13, 00, 01, +, 12, 40, 57, 980
Exoplanets detected by timing
Exoplanets discovered in 1994
Exoplanets with proper names
Pulsar planets
Science and technology in Poland
Terrestrial planets
Virgo (constellation)
Sub-Earth exoplanets