Astronomers Obtain the Most Accurate Distance for a Radio Pulsar

Astronomers Set Record Using VLBA to Accurately Measure the Distance of a Pulsar

Illustrating trigonometric parallax: the VLBA can measure the slight apparent shift in the position of an object as seen from opposite sides of the Earth’s orbit. The size of this position shift is dependent on the distance of the object from Earth. Credit: Bill Saxton, NRAO/AUI/NSF.

Using the Very Long Baseline Array, astronomers have obtained the most accurate distance for a radio pulsar to date, showing that pulsar PSR J2222-0137 is 871.4 light-years from Earth – 15% closer than previous estimates.

An international team of scientists led by astronomer Adam Deller (ASTRON) have used the Very Long Baseline Array (VLBA) to set a new distance accuracy record, pegging a pulsar called PSR J2222-0137 at 871.4 light-years from Earth. They did this by observing the object over a two-year period to detect its parallax, the slight shift in apparent position against background objects when viewed from opposite ends of Earth’s orbit around the Sun. With an uncertainty less than four light-years, this distance measurement is 30 percent more accurate than that of the previous-best pulsar distance. The VLBA observations were even able to discern the orbital motion of the pulsar around its as-yet undetected companion object, despite this motion being no larger than a small coin observed at a tenth of the distance to the Moon. The results of the research have been published in The Astrophysical Journal.

By showing that PSR J2222-0137 is 15% closer than previous estimates, this impressive achievement can advance our understanding of the system. With the distance to the pulsar pinned down, proposed highly sensitive visible-light observations should determine the nature of the undetected companion. If no source can be found, the companion must be a neutron-star, while a white-dwarf companion will show up as a faint optical source.

The accuracy of the new measurement promises to help in the quest to detect the elusive gravitational waves predicted by General Relativity. By monitoring an array of pulsars across the Milky Way galaxy, scientists hope to measure the distortions of space-time caused by the passage of gravitational waves. Knowing the distances to these pulsars extremely precisely can improve the sensitivity of the technique to detect individual sources of gravitational waves. The VLBA is operated by the National Radio Astronomy Observatory (NRAO).

Publication: A. T. Deller, et al., “VLBI astrometry of PSR J2222-0137: a pulsar distance measured to 0.4% accuracy,” 2013, ApJ, 770, 145; doi:10.1088/0004-637X/770/2/145

PDF Copy of the Study: VLBI astrometry of PSR J2222-0137: a pulsar distance measured to 0.4% accuracy

Source: ASTRON

Image: Bill Saxton, NRAO/AUI/NSF

1 Comment on "Astronomers Obtain the Most Accurate Distance for a Radio Pulsar"

  1. Recent years news related to the space about Kepler project keep amazibg me by reading newspaper in English since Reuters or AP report. Today I have something in my mind that is why tried accessing to seek news relevant to finding related to pulsar. There are a sort of jaming in Tokyo on TV or Radio but my one music pad produced by SONY is also affected but it′s about clock. I find some noise affect m-second unit. I mean it is affected by shorter than a second. When I was a university student, not only my social science study but I was engaged in sport. I had some sense of near 1/100 to 1/10 second. In UK, they introduce stronger concerns on the failure which the vanishing of airplane as the Britain had experienced more number of cases of such accidents in the past including Air France.

    Do the technology such as VLBA affect the clock on earth in pacific area ? Sorry !

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