PSR B1257+12#Planets

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. 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.{{cite book |last1=Lyne |first1=Andrew G. |last2=Graham-Smith |first2=Francis |title=Pulsar Astronomy |publisher=Cambridge University Press |year=1998 |isbn=0-521-59413-8 }}

On their discovery, the planets were designated PSR 1257+12 A, B, and C, ordered by increasing distance. They were discovered before the convention that extrasolar planets receive designations consisting of the star's name followed by lower-case Roman letters starting from "b", in order of discovery, was established.{{cite arXiv |last1=Hessman |first1=F. V. |title=On the naming convention used for multiple star systems and extrasolar planets |date=3 Dec 2010 |eprint=1012.0707 |display-authors=1 |last2=Dhillon |first2=V. S. |last3=Winget |first3=D. E. |last4=Schreiber |first4=M. R. |last5=Horne |first5=K. |last6=Marsh |first6=T. R. |last7=Guenther |first7=E. |last8=Schwope |first8=A. |last9=Heber |first9=U.|class=astro-ph.SR }} However, they are listed under the latter convention on astronomical databases such as SIMBAD and the Extrasolar Planets Encyclopaedia, with A becoming b, B becoming c, and C becoming d.

In July 2014, the International Astronomical Union launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.{{Cite web |last=International Astronomical Union |date=9 July 2014 |title=NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars |url=https://www.iau.org/news/pressreleases/detail/iau1404/ |access-date=2024-01-30 |website=iau1404 — Press Release |place=Paris}} The process involved public nomination and voting for the new names.{{cite web |last=International Astronomical Union |title=NameExoWorlds |url=http://nameexoworlds.iau.org/process |url-status=dead |archive-url=https://web.archive.org/web/20150815025117/http://www.nameexoworlds.iau.org/process |archive-date=15 August 2015 |access-date=5 October 2017}} In December 2015, the IAU announced the winning names, submitted by the Planetarium Südtirol Alto Adige in Karneid, Italy, were Lich for the pulsar and Draugr, Poltergeist, and Phobetor for planets A, B, and C, respectively:{{Cite web |last=International Astronomical Union |date=15 December 2015 |title=Final Results of NameExoWorlds Public Vote Released |url=https://www.iau.org/news/pressreleases/detail/iau1514/ |access-date=2024-01-30 |website=iau1514 — Press Release}}{{Cite web |date=3 January 2016 |title=NameExoWorlds |url=http://nameexoworlds.iau.org/systems/106 |url-status=dead |archive-url=https://web.archive.org/web/20170405053828/http://nameexoworlds.iau.org/systems/106 |archive-date=5 April 2017 |publisher=International Astronomical Union}}

• A lich is an undead creature known for controlling other undead creatures with magic.
• Draugr refers to undead creatures in Norse mythology.
• Poltergeist is a name for supernatural beings that create physical disturbances, from the German for "noisy ghost".
• Phobetor is, in Ovid's Metamorphoses, one of the thousand sons of Somnus (Sleep) who appears in dreams in the form of beasts.{{Cite journal |last=OVID |editor-first1= G. P.|editor-last1= Goold|year=1916 |title=Metamorphoses |url=https://www.loebclassics.com/view/ovid-metamorphoses/1916/pb_LCL043.165.xml |access-date=30 January 2024 |website=Loeb Classical Library |publisher=Harvard University Press |pages=164–165 |doi=10.4159/DLCL.ovid-metamorphoses.1916 |edition=Book XI|url-access=subscription }}

In 2016, the IAU organized a Working Group on Star Names (WGSN){{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|access-date=22 May 2016}} to catalog and standardize proper names for stars (including stellar remnants). In its first bulletin of July 2016,{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 |access-date=28 July 2016}} the WGSN explicitly recognized the names of exoplanets and their host stars approved by the Executive Committee Working Group Public Naming of Planets and Planetary Satellites, including the names of stars adopted during the 2015 NameExoWorlds campaign. This stellar remnant is now so entered in the IAU Catalog of Star Names.

PSR B1257+12 was discovered by the Polish astronomer Aleksander Wolszczan on 9 February 1990 using the Arecibo radio telescope. It is a millisecond pulsar, a kind of neutron star, with a rotation period of 6.22 milliseconds (9,650 rpm), and was found to have anomalies in the pulsation period, which led to investigations as to the cause of the irregular pulses. In 1992, Wolszczan and Dale Frail published a famous paper on the first confirmed discovery of planets outside the Solar System. Using refined methods one more planet was found orbiting this pulsar in 1994.

The pulsar is estimated to have a mass of 1.4 {{Solar mass}}, which is typical for most neutron stars and pulsars. The radius is estimated to be around {{Convert|10|km|mi|lk=on|disp=or}} ({{Val|1.5e-5|u={{Solar radius}}|p=~}}), also common for pulsars and neutron stars. The pulsar is extremely hot, with a surface temperature of up to around {{Convert|28,856|K|C F|lk=on}}. The pulsar formed one to three billion years ago from a white dwarf merger, a pair of white dwarfs colliding and collapsing to form a rapidly spinning pulsar.

The discovery stimulated a search for planets orbiting other pulsars, but it turned out such planets are rare; only a handful of other pulsar planets have been confirmed.

{{OrbitboxPlanet begin|table_ref=}}

{{OrbitboxPlanet

| exoplanet = A (b / Draugr)

| mass_earth = 0.020 ± 0.002

| period = 25.262 ± 0.003

| semimajor = 0.19

| eccentricity = 0.0

| inclination = ~50

}}

{{OrbitboxPlanet

| exoplanet = B (c / Poltergeist)

| mass_earth = 4.3 ± 0.2

| period = 66.5419 ± 0.0001

| semimajor = 0.36

| eccentricity = 0.0186 ± 0.0002

| inclination = 53

}}

{{OrbitboxPlanet

| exoplanet = C (d / Phobetor)

| mass_earth = 3.9 ± 0.2

| period = 98.2114 ± 0.0002

| semimajor = 0.46

| eccentricity = 0.0252 ± 0.0002

| inclination = 47

}}

{{Orbitbox end}}

File:Artist's concept of PSR B1257+12 system.jpg

In 1992, Wolszczan and Frail discovered that the pulsar had two planets. These were the first discovery of extrasolar planets to be confirmed;{{cite web |url=http://www.astro.psu.edu/users/alex/pulsar_planets.htm |title=Pulsar Planets |url-status=dead |archive-url=https://web.archive.org/web/20051230112904/http://www.astro.psu.edu/users/alex/pulsar_planets.htm |archive-date=30 December 2005 }}{{cite journal |author=Wolszczan |first1=A. |last2=Frail |first2=D. |date=1992 |title=A planetary system around the millisecond pulsar PSR1257 + 12 |journal=Nature |volume=355 |issue=6356 |pages=145–147 |bibcode=1992Natur.355..145W |doi=10.1038/355145a0 |s2cid=4260368}} as pulsar planets, they surprised many astronomers who expected to find planets only around main-sequence stars. Additional uncertainty surrounded the system, because of a claim of an earlier pulsar planet around PSR 1829-10 that had to be retracted due to errors in calculations. In 1994, an additional planet was discovered. Additionally, this system may have an asteroid belt or a Kuiper belt.

The planets are believed to be the result of a second round of planetary system formation as a result of two white dwarfs merging with each other into a pulsar and a resulting disk of material in orbit around the star.{{cite book |author=Podsiadlowski |first=P. |title=Planets Around Pulsars; Proceedings of the Conference |date=1993 |publisher=California Institute of Technology |volume=36 |pages=149–165 |chapter=Planet Formation Scenarios |bibcode=1993ASPC...36..149P}} Other scenarios include unusual supernova remnants or a quark-nova.{{cite journal |title=Planets orbiting Quark Nova compact remnants |bibcode=2003A&A...407L..51K|arxiv = astro-ph/0301574 |doi = 10.1051/0004-6361:20030957 |volume=407 |issue=3|journal=Astronomy and Astrophysics |pages=L51–L54|year=2003|last1=Keränen|first1=P.|last2=Ouyed|first2=R.|s2cid=18748570}} However, the white dwarf–white dwarf merge model seems to be the most likely cause of the formation of the planets.

In 1996, a possible Saturn-like (100 Earth mass) gas giant was announced orbiting the pulsar at a distance of about {{Convert|40|AU|e9km e9mi|abbr=unit}}.{{cite conference|last=Wolszczan|first=Alex|date=1997|title=The Pulsar Planets Update|publisher=Astronomical Society of the Pacific|pages=135|bibcode=1997ASPC..119..135W|book-title=Planets Beyond the Solar System and the Next Generation of Space Missions. Proceedings of a workshop held at Space Telescope Science Institute, Baltimore, MD, 16–18 October 1996. ASP Conference Series, Vol. 119}} The original hypothesis was retracted; a reinterpretation of the data led to a new hypothesis of a dwarf planet one-fifth the size of Pluto orbiting PSR B1257+12. It would have an average orbital distance of {{Convert|2.4|AU|e6km e6mi|abbr=unit}} with an orbital period of approximately 4.6 years.{{cite journal |last = Fischer |first = Daniel |title = A comet orbiting a pulsar? |journal = The Cosmic Mirror |issue=244 |date = 25 October 2002 |url = http://www.astro.uni-bonn.de/~dfischer/mirror/244.html}}{{cite web |title = Smallest extra-solar planet found |publisher = BBC News |date = 14 February 2005 |url = http://news.bbc.co.uk/2/hi/science/nature/4264603.stm}}{{cite journal |last=Wolszczan |first=Alex |date=January 2012 |title=Discovery of pulsar planets |journal=New Astronomy Reviews |volume=56 |issue=1 |pages=2–8 |publisher=Elsevier |bibcode = 2012NewAR..56....2W |doi = 10.1016/j.newar.2011.06.002 }}{{cite press release|url=http://live.psu.edu/story/10180|title=Scientists announce smallest extra-solar planet yet discovered|date=2005|publisher=Pennsylvania State University|url-status=dead|archive-url=https://web.archive.org/web/20081012120754/http://live.psu.edu/story/10180|archive-date=12 October 2008}} The dwarf planet hypothesis was also retracted because further observations showed that the pulsation anomalies previously thought to reveal a fourth orbital body are "not periodic and can be fully explained in terms of slow changes in the pulsar's dispersion measure".

• 51 Pegasi
• Gamma Cephei Ab
• List of exoplanets discovered before 2000 - Draugr, Poltergeist and Phobetor
• PSR B1620-26

{{Reflist|refs=

{{cite journal | url=http://www.astro.psu.edu/~niel/astro550/week07-wolszczan-pulsar-planets.pdf | author=Wolszczan, A. | title=Confirmation of Earth Mass Planets Orbiting the Millisecond Pulsar PSR B1257+12 | journal=Science | volume=264 | issue=5158 | pages=538–542 | date=1994 | doi=10.1126/science.264.5158.538 | pmid=17732735 | bibcode=1994Sci...264..538W | s2cid=19621191 | url-status=dead | archive-url=https://web.archive.org/web/20110720034147/http://www2.astro.psu.edu/~niel/astro550/week07-wolszczan-pulsar-planets.pdf | archive-date=20 July 2011 }}

{{cite journal | last1=Konacki|first1= M. | last2=Wolszczan|first2= A. | title=Masses and Orbital Inclinations of Planets in the PSR B1257+12 System | journal=The Astrophysical Journal | volume=591 | issue=2 | pages=L147–L150 | date=2003 | doi=10.1086/377093 | bibcode=2003ApJ...591L.147K|arxiv = astro-ph/0305536 | s2cid=18649212 }}

{{cite journal | title=Very long baseline interferometry astrometry of PSR B1257+12, a pulsar with a planetary system | last1=Yan | first1=Zhen | last2=Shen | first2=Zhi-Qiang | last3=Yuan | first3=Jian-Ping | last4=Wang | first4=Na | last5=Rottmann | first5=Helge | last6=Alef | first6=Walter | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society | volume=433 | issue=1 | pages=162–169 | year=2013 | bibcode=2013MNRAS.433..162Y | doi=10.1093/mnras/stt712 | doi-access=free }}

{{cite journal |last1=Laycock |first1=Silas G. T. |last2=Christodoulou |first2=Dimitris M. |date=March 2025 |title=On the Number of Confirmed Pulsar Planets: The Rule of Six |journal=The Astrophysical Journal |volume=982 |issue=1 |pages=63 |doi=10.3847/1538-4357/adb1a8 |doi-access=free |bibcode=2025ApJ...982...63L}}

{{cite constellation|PSR B1257+12}}

}}

{{Refbegin}}

• {{cite journal|bibcode=2000ApJ...528..907W|author=Wolszczan, A.|display-authors=etal|title=Timing Observations of Four Millisecond Pulsars with the Arecibo and Effelsberg Radio Telescopes|journal=The Astrophysical Journal|volume=528|issue=2|pages=907–912|date=2000|doi=10.1086/308206|doi-access=free}}
• {{cite journal|url=http://www.naic.edu/~newslet/no33/NAICNo33.pdf|author=Salter, C.|title=Radio Astronomy Highlights|journal=Arecibo Newsletter|issue=33|date=2001|access-date=24 July 2006|archive-date=19 December 2008|archive-url=https://web.archive.org/web/20081219192204/http://www.naic.edu/~newslet/no33/NAICNo33.pdf|url-status=dead}}

{{Refend}}

• [https://web.archive.org/web/20051230112904/http://www.astro.psu.edu/users/alex/pulsar_planets.htm Pulsar Planets]
• [https://web.archive.org/web/20080525161540/http://exoplanet.eu/star.php?st=PSR+1257+12 PSR 1257+12] on [https://web.archive.org/web/20080613163808/http://exoplanet.eu/index.php The Extrasolar Planets Encyclopaedia]
• {{cite news

|first=Robert Roy

|last=Britt

|title= A World With Two Suns

|url=http://www.space.com/scienceastronomy/aas_earthsize_020329.html

|publisher=SPACE.com

|date=29 May 2003

}}

• Lytle, Wayne (1992). [https://www.youtube.com/watch?v=UrhfVH8itPE "Does This Pulsar Have Orbiting Planets?"]. Cornell Theory Center

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Category:Planetary systems with three confirmed planets

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