A SpaceX Falcon 9 rocket launches with NASA’s Imaging X-ray Polarimetry Explorer (IXPE) spacecraft onboard from Launch Complex 39A, Thursday, Dec. 9, 2021, at NASA’s Kennedy Space Center in Florida. The IXPE spacecraft is the first satellite dedicated to measuring the polarization of X-rays from a variety of cosmic sources, such as black holes and neutron stars. Launch occurred at 1 a.m. EST.
Credits: NASA/Joel Kowsky
A new mission has launched to study some the most intriguing secrets of the universe. No, not THAT spacecraft (JWST is scheduled for launch on December 22). Another new and exciting mission is called Imaging X-ray Polarimetry Explorer (IXPE) and it will allow scientists to explore the hidden details of some of the most extreme and high-energy objects in the cosmos, such as black holes, neutron stars, pulsars and dozens of other objects.
This artist’s impression shows the material ejected from the region around the supermassive black hole in the quasar SDSS J1106+1939. This object has the most energetic outflows ever seen, at least five times more powerful than any that have been observed to date. Quasars are extremely bright galactic centres powered by supermassive black holes. Many blast huge amounts of material out into their host galaxies, and these outflows play a key role in the evolution of galaxies. But, before this object was studied, the observed outflows weren’t as powerful as predicted by theorists. The very bright quasar appears at the centre of the picture and the outflow spreads about 1000 light-years out into the surrounding galaxy.
Astronomers have been using gravitational waves to detect merging black holes for years now, but may have to rely on pulsars – rapidly spinning neutron stars – to observe the mergers of supermassive black holes.
It was the brightest supernova in nearly 400 years when it lit the skies of the southern hemisphere in February 1987. Supernova 1987A – the explosion of a blue supergiant star in the nearby mini-galaxy known as the Large Magellanic Cloud – amazed the astronomical community. It offered them an unprecedented opportunity to observe an exploding star in real-time with modern instruments and telescopes. But something was missing. After the supernova faded, astronomers expected to find a neutron star (a hyper-dense, collapsed stellar core, made largely of neutrons) left-over at the heart of the explosion. They saw nothing.
Artist view of orbiting black holes. Credit: Caltech/R. Hurt (IPAC)
Gravitational-wave astronomy is still in its infancy. LIGO and other observatories have opened a new window on the universe, but their gravitational view of the cosmos is limited. To widen our view, we have the North American Nanohertz Observatory for Gravitational Waves (NANOGrav).
Artist's impression of an Accreting X-Ray Pulsar drawing material from its companion star. - NASA
We recently observed the strongest magnetic field ever recorded in the Universe. The record-breaking field was discovered at the surface of a neutron star called GRO J1008-57 with a magnetic field strength of approximately 1 BILLION Tesla. For comparison, the Earth’s magnetic field clocks in at about 1/20,000 of a Tesla – tens of trillions of times weaker than you’d experience on this neutron star…and that is a good thing for your general health and wellbeing.
Neutron stars are the “dead cores” of once massive stars which have ended their lives as supernova. These stars exhausted their supply of hydrogen fuel in their core and a power balance between the internal energy of the star surging outward, and the star’s own massive gravity crushing inward, is cataclysmically unbalanced – gravity wins. The star collapses in on itself. The outer layers fall onto the core crushing it into the densest object we know of in the Universe – a neutron star. Even atoms are crushed. Negatively charged electrons are forced into the atomic nuclei meeting their positive proton counterparts creating more neutrons. When the core can be crushed no further, the outer remaining material of the star rebounds back into space in a massive explosion – a supernova. The resulting neutron star, made of the crushed stellar core, is so dense that a single sugar-cube-sized sampling would weigh billions of tons – as much as a mountain (though if you’re “worthy” you MIGHT able to lift it since Thor’s Hammer is made of the stuff). Neutron stars are typically about 20km in diameter and can still be a million degrees Kelvin at the surface.
But if they’re “dead,” how can neutron stars be some of the most magnetic and powerful objects in the Universe?
Pulsars are fast-spinning neutron stars that emit narrow, sweeping beams of radio waves. A new study identifies the origin of those radio waves. NASA’s Goddard Space Flight Center
When pulsars were first discovered in 1967, their rhythmic radio-wave pulsations were a mystery. Some thought their radio beams must be of extraterrestrial origin.
We’ve learned a lot since then. We know that pulsars are magnetized, rotating neutrons stars. We know that they rotate very rapidly, with their magnetic poles sending sweeping beams of radio waves out into space. And if they’re aimed the right way, we can “see” them as pulses of radio waves, even though the radio waves are steady. They’re kind of like lighthouses.
But the exact mechanism that creates all of that electromagnetic radiation has remained a mystery.
The Five-hundred-metre Aperture Spherical Telescope (FAST) has just finished construction in the southwestern province of Guizhou. Credit: FAST
In 2016, China’s Five-hundred-meter Aperture Spherical radio Telescope – the largest single-aperture radio telescope in the world – gathered its first light. Since then, the telescope has undergone extensive testing and commissioning and officially went online in Jan of 2020. In all that time, it has also been responsible for multiple discoveries, including close to one hundred new pulsars.
According to a recent study by an international team of scientists and led by the Chinese Academy of Sciences (CAS) suggests that FAST might have another use as well: the search for extraterrestrial intelligence (SETI)! Building on their collaboration with the non-profit science organization Breakthrough Initiatives, the authors of the study highlight the ways in which FAST could allow for some novel SETI observations.
An artist’s impression of the star with its tidally locked red dwarf companion. Credit: Gabriel Pérez Díaz (IAC)
In the 17th century, astronomers witnessed many stellar events that proved that the starry sky was not “fixed and eternal.” This included stars whose brightness varied over time – aka. “variable stars.” By the 20th century, many variable stars had been cataloged and astronomers have discerned subclasses of them as well – notably, stars that swell and shrink, known as pulsating variables.
In all cases, these variable stars were found to have rhythmic pulsations that were visible from all sides. But a recent discovery by an international team has confirmed that there are variable stars that can pulse from only one side. This pulsating star, part of a system known as HD 74423, is located about 1,500 light-years from Earth and is the first of its kind to be found.
A map of gamma ray emissions throughout the Milky Way galaxy, based on observations from the Fermi Gamma-ray Space Telescope. The inset depicts the Galactic Center Excess – an unexpected, spherical region of gamma ray emissions at the center of our galaxy, of unknown origin. Credit: NASA/T. Linden, U.Chicago
There’s a lot of mysterious goings-on at the center of the Milky Way. The supermassive black hole that resides there is chief among them. But there’s another intriguing puzzle there: an unexpected spherical region of intense gamma ray emissions.
A new study suggests that dark matter could be behind those emissions.
A representation of how our Galaxy would look in the sky if we could see magnetic fields. The plane of the Galaxy runs horizontally through the middle, and the Galactic centre direction is the middle of the map. Red–pink colours show increasing Galactic magnetic field strengths where the direction is pointing towards the Earth. Blue–purple colours show increasing Galactic magnetic field strengths where the direction is pointing away from the Earth. The background shows the signal reconstructed using sources outside our Galaxy. The points show the current measurements for pulsars. The squares show the measurements from this work using LOFAR pulsar observations. Image Credit: Sobey et al, 2019.
The Milky Way galaxy has its own magnetic field. It’s extremely weak compared to Earth’s; thousands of times weaker, in fact. But astronomers want to know more about it because of what it can tell us about star formation, cosmic rays, and a host of other astrophysical processes.
