PSR J0348+0432

Key takeaways

PSR J0348+0432 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PSR J0348+0432 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PSR J0348+0432 from memory before moving on to harder problems.

Reference excerpt

PSR J0348+0432 is a pulsar–white dwarf binary system in the constellation Taurus. It was discovered in 2007 with the National Radio Astronomy Observatory's Robert C. Byrd Green Bank Telescope in a drift-scan survey. In 2013, a mass measurement for this neutron star was announced: slightly over two times the mass of the Sun (2.01±0.04 M☉). This measurement was done with a combination of radio timing and precise spectroscopy of the white dwarf companion. This is slightly higher than, but statistically indistinguishable from, the mass of PSR J1614−2230, which was measured using the Shapiro delay. This measurement confirmed the existence of such massive neutron stars using a different measuring technique. The notable feature of this binary pulsar is its combination of high neutron-star mass and short orbital period: 2 hours and 27 minutes. This allowed a measurement of the orbital decay due to the emission of gravitational waves, as observed for PSR B1913+16 and PSR J0737−3039.

Background

The first radio pulsar was discovered in 1967 by Jocelyn Bell and her adviser, Antony Hewish using the Interplanetary Scintillation Array. Franco Pacini and Thomas Gold quickly put forth the idea that pulsars are highly magnetized rotating neutron stars, which form as a result of a supernova at the end of the life of stars more massive than about 10 times the mass of the Sun. The radiation emitted by pulsars is caused by interaction of the plasma surrounding the neutron star with its rapidly rotating magnetic field. This interaction leads to emission "in the pattern of a rotating beacon", as emission escapes along the magnetic poles of the neutron star. The "rotating beacon" property of pulsars arises from the misalignment of their magnetic poles with their rotational poles. Historically, pulsars have been discovered at radio wavelengths where emission is strong, but space telescopes that operate in the gamma ray wavelengths have also discovered pulsars.

Observations In 2007, the Green Bank Telescope underwent track repair, and was unable to track for several months. An international team of astronomers was nevertheless able to record the data from the antenna, letting the Earth do the job of moving the beam of the telescope across the sky, a process known as a drift scan survey. They found a total of 35 new pulsars, including 7 new millisecond pulsars and PSR J0348+0432. In 2011 the white dwarf companion to the pulsar was observed with the FORS2 spectrograph of the European Southern Observatory's Very Large Telescope, in Chile. These data were combined with radio observations to determine the mass of the white dwarf and the pulsar. Radio timing of the pulsar with the 305-metre radio telescope at the Arecibo Observatory and the Effelsberg 100-metre Radio Telescope soon also detected the orbital decay of the system due to the emission of gravitational waves. This matched the rate predicted by general relativity.

Significance The combination of a large neutron-star mass, low white-dwarf mass (mass ratio ~ 1:11.7) and short orbital period (2 hours and 27 minutes) allows astronomers to test general relativity in a regime of extreme gravitational fields, where it had never been tested before. The result also has implications for the direct detection of gravitational waves and for understanding of stellar evolution. The measured mass of 2.01±0.04 M☉ puts an empirical lower bound on the value of the Tolman–Oppenheimer–Volkoff limit. PSR J0348+0432 is also a candidate for a hyperon star, a massive neutron star containing hyperons.

Notes

References Antoniadis, J.; Freire, P. C. C.; Wex, N.; Tauris, T. M.; Lynch, R. S.; Van Kerkwijk, M. H.; Kramer, M.; Bassa, C.; Dhillon, V. S.; Driebe, T.; Hessels, J. W. T.; Kaspi, V. M.; Kondratiev, V. I.; Langer, N.; Marsh, T. R.; McLaughlin, M. A.; Pennucci, T. T.; Ransom, S. M.; Stairs, I. H.; Van Leeuwen, J.; Verbiest, J. P. W.; Whelan, D. G. (2013). "A Massive Pulsar in a Compact Relativistic Binary". Science. 340 (6131) 1233232. arXiv:1304.6875. Bibcode:2013Sci...340..448A. doi:10.1126/science.1233232. PMID 23620056. S2CID 15221098. Cowen, Ron (25 April 2013). "Massive double star is latest test for Einstein's gravity theory". Nature. doi:10.1038/nature.2013.12880. S2CID 123752543. Retrieved 12 May 2013. Demorest, P. B.; Pennucci, T.; Ransom, S. M.; Roberts, M. S. E.; Hessels, J. W. T. (2010). "A two-solar-mass neutron star measured using Shapiro delay". Nature. 467 (7319): 1081–1083. arXiv:1010.5788. Bibcode:2010Natur.467.1081D. doi:10.1038/nature09466. PMID 20981094. S2CID 205222609. Gold, T. (1968). "Rotating Neutron Stars as the Origin of the Pulsating Radio Sources". Nature. 218 (5143): 731–732. Bibcode:1968Natur.218..731G. doi:10.1038/218731a0. S2CID 4217682. Hewish, A.; Bell, S. J.; Pilkington, J. D. H.; Scott, P. F.; Collins, R. A. (1968). "Observation of a Rapidly Pulsating Radio Source". Nature. 217 (5130): 709. Bibcode:1968Natur.217..709H. doi:10.1038/217709a0. S2CID 4277613. Lynch, R. S.; Boyles, J.; Ransom, S. M.; Stairs, I. H.; Lorimer, D. R.; McLaughlin, M. A.; Hessels, J. W. T.; Kaspi, V. M.; Kondratiev, V. I.; Archibald, A. M.; Berndsen, A.; Cardoso, R. F.; Cherry, A.; Epstein, C. R.; Karako-Argaman, C.; McPhee, C. A.; Pennucci, T.; Roberts, M. S. E.; Stovall, K.; Van Leeuwen, J. (2013). "The Green Bank Telescope 350 MHz Drift-scan Survey II: Data Analysis and the Timing of 10 New Pulsars, Including a Relativistic Binary". The Astrophysical Journal. 763 (2): 81. arXiv:1209.4296. Bibcode:2013ApJ...763...81L. doi:10.1088/0004-637X/763/2/81. S2CID 52043066. "A Heavyweight for Einstein". Max Planck Institute for Radio Astronomy, Bonn. 25 April 2013. Retrieved 13 May 2013. Pacini, F. (1968). "Rotating Neutron Stars, Pulsars and Supernova Remnants". Nature. 219 (5150): 145–146. arXiv:astro-ph/0208563. Bibcode:1968Natur.219..145P. doi:10.1038/219145a0. S2CID 4188947. Zhao, Xian-Feng (2017a). "Can the massive neutron star PSR J0348+0432 be a hyperon star?". Acta Physica Polonica B. 48 (2): 171. arXiv:1712.08870. Bibcode:2017AcPPB..48..171Z. doi:10.5506/APhysPolB.48.171. ISSN 0587-4254. S2CID 119207371. Zhao, Xian-Feng (2017b). "The hyperons in the massive neutron star PSR J0348+0432". Chinese Journal of Physics. 53 (4): 221–234. arXiv:1712.08854. doi:10.6122/CJP.20150601D.

Illustrations

Worked examples

Example 1 — a first encounter with PSR J0348+0432

Start with the simplest possible case. Write down what PSR J0348+0432 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to PSR J0348+0432 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about PSR J0348+0432 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of PSR J0348+0432

In research: PSR J0348+0432 appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses PSR J0348+0432 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: PSR J0348+0432 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Binary stars, Millisecond pulsars, Multiple compact object systems, so understanding it makes those chapters shorter.
In everyday life: Look for PSR J0348+0432 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study PSR J0348+0432 in 20 minutes

Read the reference excerpt below once, without taking notes.
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Frequently asked questions

What is PSR J0348+0432 in simple terms?

PSR J0348+0432 is a pulsar–white dwarf binary system in the constellation Taurus. It was discovered in 2007 with the National Radio Astronomy Observatory's Robert C.

Why does PSR J0348+0432 matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study PSR J0348+0432?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on PSR J0348+0432.