Pulsar
For example, observations of a pulsar in a binary neutron star system were used to indirectly confirm the existence of gravitational radiation.[3] Signals from the first discovered pulsar were initially observed by Jocelyn Bell while analyzing data recorded on August 6, 1967, from a newly commissioned radio telescope that she helped build.Initially dismissed as radio interference by her supervisor and developer of the telescope, Antony Hewish,[4][5] the fact that the signals always appeared at the same declination and right ascension soon ruled out a terrestrial source.[6] On November 28, 1967, Bell and Hewish using a fast strip chart recorder resolved the signals as a series of pulses, evenly spaced every 1.337 seconds.On December 21, Bell discovered a second pulsar, quashing speculation that these might be signals beamed at earth from an extraterrestrial intelligence.At this point, Bell said of herself and Hewish that "we did not really believe that we had picked up signals from another civilization, but obviously the idea had crossed our minds and we had no proof that it was an entirely natural radio emission.The word "pulsar" first appeared in print in 1968: An entirely novel kind of star came to light on Aug. 6 last year and was referred to, by astronomers, as LGM (Little Green Men).[24] Considerable controversy is associated with the fact that Hewish was awarded the prize while Bell, who made the initial discovery while she was his PhD student, was not.Factors affecting the arrival time of pulses at Earth by more than a few hundred nanoseconds can be easily detected and used to make precise measurements.The goal of these efforts is to develop a pulsar-based time standard precise enough to make the first ever direct detection of gravitational waves.In 2006, a team of astronomers at LANL proposed a model to predict the likely date of pulsar glitches with observational data from the Rossi X-ray Timing Explorer.This discovery presented important evidence concerning the widespread existence of planets outside the Solar System, although it is very unlikely that any life form could survive in the environment of intense radiation near a pulsar.[36] According to this model, AE Aqr is an intermediate polar-type star, where the magnetic field is relatively weak and an accretion disc may form around the white dwarf.A similar model for eRASSU J191213.9−441044 is supported by the results of its observations at ultraviolet wave lengths, which showed that its magnetic field strength does not exceed 50 MG.[37] Initially pulsars were named with letters of the discovering observatory followed by their right ascension (e.g. CP 1919).The neutron star retains most of its angular momentum, and since it has only a tiny fraction of its progenitor's radius, it is formed with very high rotation speed.This turn-off seems to take place after about 10–100 million years, which means of all the neutron stars born in the 13.6-billion-year age of the universe, around 99% no longer pulsate.The process of accretion can, in turn, transfer enough angular momentum to the neutron star to "recycle" it as a rotation-powered millisecond pulsar.According to a study published in 2023,[58] the timing noise observed in pulsars is believed to be caused by background gravitational waves.Alternatively, it may be caused by stochastic fluctuations in both the internal (related to the presence of superfluids or turbulence) and external (due to magnetospheric activity) torques in a pulsar.Free electrons in the warm (8000 K), ionized component of the ISM and H II regions affect the radiation in two primary ways.[63] The exact cause of these density inhomogeneities remains an open question, with possible explanations ranging from turbulence to current sheets.[64] Pulsars orbiting within the curved space-time around Sgr A*, the supermassive black hole at the center of the Milky Way, could serve as probes of gravity in the strong-field regime.[65] Arrival times of the pulses would be affected by special- and general-relativistic Doppler shifts and by the complicated paths that the radio waves would travel through the strongly curved space-time around the black hole.
Neutron star types (24 June 2020)
Pulsar (disambiguation)PSR B1509−58X-raysChandrainfraredlighthouseneutron starelectromagnetic radiationperiodsultra-high-energy cosmic rayscentrifugal mechanism of accelerationbinary neutron star systemgravitational radiationextrasolar planetsPSR B1257+12certain types of pulsarsatomic clockskeeping timefirst discovered pulsarJocelyn Bellnewly commissioned radio telescoperadio interferenceAntony Hewishdeclinationright ascensionchart recorderextraterrestrial intelligencelittle green menbeings of extraterrestrial originCambridge University LibraryCP 1919radio wavelengthsgamma rayCrab Nebulasynchrotron emissionpulsar wind nebulaWalter BaadeFritz ZwickysupernovaLodewijk WoltjerFranco Pacinisupernova remnantThomas GoldRichard V. E. LovelaceCrab Nebula pulsarArecibo ObservatoryCrab pulsarmillisecondMartin Ryleradio telescopesNobel Prize in PhysicsRoyal Swedish Academy of SciencesVela PulsarJoseph Hooton Taylor, Jr.Russell Hulsebinary systemPSR B1913+16Einsteingeneral relativityorbital energyDon BackerPSR B1937+21millisecond pulsarsX-ray binariesastronomersnanosecondsproper motionelectroninterstellar mediumTerrestrial Timepulsar timing arraytime standardpulsar glitchesRossi X-ray Timing ExplorerPSR J0537−6910Aleksander WolszczanSolar Systemlife formWhite dwarfsmoment of inertiaAE AquariiX-ray pulsarAR ScorpiiCornell Universityintermediate polaraccretion discmagnetospherePSR J0437−4715angular momentumradiationconservation of momentumangular speedrotational energyelectromagneticMax Planck Institute for Extraterrestrial Physicsaccretion-powered pulsarsX-ray pulsarsgravitational potential energyaccretedmagnetarsmagnetic fieldbinary companionsmillisecond pulsarglitchesstarquakessuperconductingnuclearGalaxyPioneer plaquePioneer plaquesVoyager Golden RecordextraterrestrialX-ray pulsar-based navigationpulsarsradio wavesX-ray telescopesephemeris timepulsar clocksgravitational waveselectronsH II regionsdispersiveplasmadispersion measurecolumn densityMilky Way