7.08.2024
"It's very unusual to find exotic new pulsars. But what's really exciting is the wide variety of such weirdos in a single cluster!"
An illustration of ten rapidly rotating dead star pulsars in Terzan 5. (Image credit: US NSF, AUI, NSF NRAO, S. Dagnello)
Astronomers have discovered ten strange dead stars, or "neutron stars," lurking near the heart of the Milky Way. These weirdo neutron stars are also spinning, meaning they are "pulsars." Scientists suspect the overly dense nature of this oddball globular cluster, located 18,000 light-years from Earth, could result in these rapidly spinning dead stars taking on bizarre and twisted forms.
The lot, for instance, includes several "spider pulsars" that destroy stars with plasma webs and a speed demon vampire star greedily feasting on its companion stars.
Pulsars are neutron stars that can spin as fast as 700 times per second. They blast out beams of radiation from their poles that sweep across space like the beam of a celestial lighthouse. These newly uncovered pulsars are located together in the globular cluster Terzan 5, which is home to hundreds of thousands of different types of stars with ages between 12 billion and 4.5 billion years. Astronomers were already aware of 39 pulsars in Terzan 5, one of the most crowded regions in the Milky Way.
"It's very unusual to find exotic new pulsars," Scott Ransom, a scientist with the U.S. National Science Foundation National Radio Astronomy Observatory (NSF NRAO) said in a statement. "But what’s really exciting is the wide variety of such weirdos in a single cluster."
Ransom and colleagues discovered the pulsars with the Green Bank Telescope and the MeerKAT Telescope. Tracking the location of the neutron stars and the timing of their rotations with MeerKAT and then comparing this to 20 years of Terzan 5 observations — made using the Green Bank Telescope — revealed the bizarre characteristics of these newly found dead stars.
Two neutron stars are part of an incredibly rare double neutron-star binary, for example. Astronomers have discovered around 3,600 pulsars in the Milky Way, but only 20 of them have been double neutron-star binaries.
When these binaries form, one of the neutron stars pulls material from the other like a cosmic vampire. This transferred matter carries with it angular momentum that increases the spin of the neutron star, creating a "millisecond pulsar" that can spin hundreds of times per second. The newly found pair could set a record for such an object, appearing to spin faster than 716 rotations per second, the spin speed of the current record holder PSR J1748−2446ad, which is also located in Terzan 5.
This speed demon dead star wasn't the only monster found lurking in Terzan 5, however.
The team also uncovered three new rare spider pulsars. These pulsars are classed either as "Redbacks" or "Black Widows," depending on the nature of the companion star they devour.
Both types of stars waste away companion stars that come too close with a "web" of high-energy radiation. Redback spider pulsars prey on companion stars with masses between 10% and 50% of the sun's mass, while Black Widow spider pulsars ravage smaller stars with less than 5% of the sun's mass.
The discovery of the "monster mash" of fearsome neutron stars could help astronomers better understand pulsars and the effect that evolving in a globular cluster can have on them.
The researchers are already hoping to discover more of these cosmic weirdos in Terzan 5, calling on the assistance of brave citizen scientists. If you have what it takes to join this cosmic "monster squad," you can commit your idle computer time to the Einstein@Homeproject, which has already uncovered 90 new neutron stars,
The team's research is published in the journal Astronomy & Astrophysics.
Quelle: SC