Pulsars are usually neutron stars, but we now know they can also be a white dwarf.
How Do You Weigh A Neutron Star?
New work in Science Advances has found an interesting way to determine the mass of a type of neutron star known as a pulsar.
Closest Approach
Cue the dramatic music. A pulsar will be making a close approach to a star in 2018.
Run Silent, Run Deep
The pulsar J1906+0746 has gone silent, and that’s good news for general relativity.
Finding a Pulse
An ultraluminous x-ray source (ULX) is an intense, localized sources of x-rays. They are generally powered by solar-mass black holes, similar to the way quasars and blazars are powered by supermassive black holes. We’ve generally thought only black holes could provide enough power to generate such powerful x-rays, but now it seems that isn’t always the case. New results have been published in Nature that show some of them might be powered by accreting neutron stars.
Eat and Run
A millisecond pulsar is a neutron star that is rotating about 600 to 700 times a second. Because of their strong magnetic fields, they produce strong beams of radio energy from the regions of their magnetic poles, and as they rotate these beams can point in our direction. As a result, we observe these neutron stars as radio bursts that pulse every 1 – 10 milliseconds. Hence their name.
Glitch and Anti-Glitch
About a year ago in Nature astronomers reported evidence of an anti-glitch in the magnetar 1E 2259+586. You might remember from yesterday’s post that a magnetar is a neutron star with an extremely strong magnetic field. This particular magnetar is also a pulsar, meaning that the intense x-ray beams that stream from the magnetar’s polar region happen to be aligned so that we see it flash regularly. You can think of a pulsar as a kind of cosmic lighthouse, if you will.
Magnetars, Pulsars, and X-rays, Oh My!
One of the differences between astronomy and astrophysics is that astronomy is based upon observation, while astrophysics is about the underlying mechanism behind those observations. For this reason, many types of phenomena in the universe have multiple names depending on how we observe them. The reason for this is that typically astronomers start observing different phenomena, give them names, and then only later do astrophysicists figure out that they are different examples of the same thing. By then the names have already stuck.
Pico Arcseconds
One of the advantages of radio astronomy is that you can connect observations from radio telescopes thousands of miles apart. Done in the right way, this creates a radio interferometer that effectively makes a virtual telescope as big as the separation (baseline) of the individual telescopes. The bigger your telescope (or virtual telescope), the finer the detail of your image. When we talk about the detail level of an astronomical image, we usually talk about the angle of separation between two distinctly resolvable points. So a resolution of a tenth of a degree would mean you could resolve two points of light (such as stars) separated by at least that angle.
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