Astronomy and space news summarized by Don Lynn from NASA and other sources

Black Hole Magnetic Field – In 2019, astronomers unveiled the first ever picture of a black hole, or more precisely, the material surrounding the supermassive black hole at the center of galaxy M87. Further processing of that image data by the Event Horizon Collaboration revealed the polarization of its light. This polarization is caused by electrons deflected by magnetic fields, so the new image shows magnetic fields around that black hole. Astronomers expected the light around a black hole to be mostly polarized, but found it only to be 15 percent polarized. From this they concluded that the magnetization is chaotic over small distances, which muddles much of the polarization.

Double Quasars Found – Quasars are supermassive black holes at the centers of galaxies that are feeding on enormous quantities of material that glows brightly before falling past the black hole event horizon. When two galaxies collide, it can produce a double quasar, but such pairs are rare. A team of astronomers at the University of Illinois at Urbana-Champaign tested a new method of looking for these rarities. First they searched for quasars in data from the Sloan Digital Sky Survey, then looked at the same objects in Gaia space telescope data to see if there were small variations among the multiple times Gaia measured position. Such variations can be caused by independent flaring of two quasars that are too close to resolve separately. Then these candidates were observed with the Hubble Space Telescope to see if its superior resolution saw a double quasar. Two new double quasars were found in the first trial of this method.

Intermediate-Mass Black Hole – Gamma-ray bursts occur randomly in time and location on the sky. Occasionally double bursts are seen, and it is believed that these are caused by the gamma rays passing near a massive object that causes a gravitationally lensed double image. A team of astronomers at the University of Melbourne analyzed one such double burst and found that the object that lensed the burst had a mass of about 55,000 suns, an apparent intermediate-mass black hole. Such black holes fall between stellar-mass black holes formed by collapsing stars, and supermassive black holes found at the centers of galaxies. Extremely few of these intermediate-mass black holes are known. This is the first time one has been found by this gamma-ray burst method.

Einstein Crosses – When a quasar lines up perfectly behind a massive object, as seen from Earth, the quasar light is distorted by gravitational lensing into a perfect ring, known as an Einstein ring. But if everything is not quite perfectly lined up, the quasar can be seen as four images, known as an Einstein cross. Only about 50 of these crosses are known. An international team of astronomers trained a computer program to recognize Einstein crosses, and it found twelve new ones in Gaia space telescope data. Astronomers then used the WISE space telescope and ground-based spectroscopic observations to confirm these twelve crosses. Einstein crosses can be used to calculate the expansion rate of the Universe, known as the Hubble Constant, and to determine the distribution of dark matter about a gravitationally-lensing galaxy.

Yellowballs – Citizen scientists tasked with identifying massive stars in the process of forming in infrared images have discovered a new type of astronomical object that astronomers are calling “yellowballs.” They appear yellow only because yellow was used to false color particular wavelengths of infrared light in the images searched. Yellowballs indicate the early stages of stars of small or large mass forming. This is a useful way to search for star formation, as newly formed stars themselves are usually hidden within dusty clouds.

Star Formation – Only about 30 percent of the gas in a star-forming cloud ends up collapsing in the final star, so something is stopping the star formation process. One theory is that jets and stellar wind from the forming star blow away the remaining gas that hasn’t yet collapsed. However, a new study casts doubt on that theory. Astronomers at the University of Toledo in Ohio studied 304 forming stars of varying ages in the Orion Complex, using archived date from the Hubble, Spitzer and Herschel space telescopes, and found that the gas blowing away from jets and winds does not occur at the same time as the growth of the forming star ends. In fact, the jets and winds do not appear to ever blow away all the remaining gas. Astronomers are now looking for a different theory as to what ends the formation process of new stars.

GRPs in X-rays – Some pulsars, which are spinning neutron stars, occasionally emit large pulses of radio waves, dubbed giant radio pulses (GRPs). Astronomers at RIKEN have been searching for simultaneous pulses in wavelengths of light other than radio, but had come up empty-handed (except for the Crab Nebula pulsar where correlated visible light and radio pulses have been found). The search has finally found X-ray pulses associated with GRPs. Surprisingly the X-ray pulses they observed contained much more energy than the GRPs, meaning theorists have yet to find a process occurring at a neutron star that gives off pulses with perhaps hundreds of times more energy than the GRPs themselves. The new observations did not show any relation between GRPs and the mysterious fast radio bursts, whose cause is also unknown.

Ingenuity – The Mars helicopter, named Ingenuity, failed its rotor-spinning test on April 9. After controllers fixed a software problem in synchronizing two computers, the test succeeded on April 16, and was followed three days later by a flight to about ten feet off the ground for more than 30 seconds, making it the first powered flight on another planet. Rover Perseverance imaged the flight from a safe distance away. Ingenuity made its second flight three days later. This time it flew 16 feet high, turned to take pictures in specific directions, flew sideways, and spent nearly a minute in the air. A total of five flights are planned, each testing more capabilities than the previous ones. Ingenuity is intended only to test the helicopter concept, and then the rover will leave the copter behind. But what is learned will allow the team to plan how a future helicopter can scout ahead of a rover or visit places a rover cannot go, such as canyons, caves or cliffs.

Perseverance is otherwise keeping busy, taking pictures, monitoring the weather, and zapping rocks to determine their composition. It also made the first of at least 10 planned test runs of the MOXIE experiment. This device draws in carbon dioxide from the Martian atmosphere and splits it into oxygen and waste carbon monoxide. This first test run produced only a fraction of an ounce of oxygen, but later runs should far exceed this. In the future, this process could provide oxygen for astronauts to breathe and for rocket propulsion to lift off Mars.

Marsquakes – Mars lander InSight detected two strong marsquakes in March, registering 3.1 and 3.3. Although the lander has detected over 500 quakes since deploying the seismometer more than two Earth years ago, only two previous ones have been as strong as this. The stronger quakes allow much more to be learned about the Red Planet than do the weaker ones. All four of the strong quakes originated from ground motion in an area of Mars named Cerberus Fossae. Also, all occurred in northern Martian summer. This may be a selection effect, though, since bad winter weather interferes with the seismometer. Controllers have begun using the lander’s arm to scoop up soil and pile it on the cable between the seismometer and lander and on the seismometer shield, to help reduce weather interference.

Unusual Martian Crater – Scientists at Brown University discovered a crater on Mars that shows signs of liquid water running within it long ago, but without any entry streambed and without any evidence of a groundwater source. They concluded that the water source ran into the crater on a glacier, thus not leaving a streambed in the soil. There are ridges in the crater that appear to show the presence of an ancient glacier. The crater was the only one of this type at the time of discovery, but a further search by the scientists has found dozens of similar ones. These indicate that the times in the distant past when Mars had liquid water running on its surface may have been cold enough to also have glaciers.

Apophis – Remember a few years ago when astronomers said that the asteroid Apophis was going to come awfully close to us in 2029 and possibly even collide with Earth? And then a few years later, after more precise tracking, they announced Apophis would definitely miss us in 2029, but might hit Earth in 2068? Well, you can rest easy now. The asteroid came reasonably near Earth in March, giving astronomers at NASA’s Center for Near-Earth Object Studies the chance to track it with radar, yielding extremely precise positions. It is now certain that Apophis will not hit Earth in the next 100 years. Apophis is about 1,100 feet across, large enough to do serious damage in a collision. The Goldstone, California, 230-foot radio dish was used to transmit the radar, and the Green Bank 330-foot dish in West Virginia received. This combination results in amazing resolution, producing rough images of the asteroid’s surface features from more than 10 million miles away.

Pristine Comet – In late 2019, the second ever interstellar object was discovered and named Comet Borisov, after the amateur astronomer who discovered it. Its speed as it approached the Sun was too great to have originated anywhere within the Solar System, and hence was declared an interstellar object. Researchers at the European Southern Observatory analyzed Borisov observations and found that it probably had never been hot before, and therefore was making its first pass anywhere near any star. This likely makes it the most pristine comet ever observed, its composition unchanged by radiation or stellar wind since it formed. The previous most pristine comet is generally believed to have been Comet Hale-Bopp, which was thought to have made only one previous pass near the Sun.

Talc Comet – The nucleus of any comet is difficult to observe from Earth because as it comes this close to the Sun, it is usually obscured by gas and dust forming the comet coma. However, comet P/2016 BA₁₄ emitted little gas and dust, apparently because much of its volatile surface material had already been lost from many passages near the Sun. It passed quite close to Earth, giving astronomers at the National Astronomical Observatory of Japan an excellent opportunity to observe it, including in the infrared, offering the best view of a comet nucleus ever seen from Earth. They found that the surface was covered with grains of phyllosilicate, similar to talcum powder. This is the first time this mineral has been found on a comet nucleus. The observations also showed that the nucleus was about 2,600 feet in diameter.

TESS Exoplanets – The team operating the TESS planet-finding space telescope has released a new catalog of probable exoplanets, containing more than 2,200 candidates. So far about 120 have been confirmed to be exoplanets by other observations. The catalog is the result of the team at the Massachusetts Institute of Technology finishing the telescope’s mosaiced coverage of most of the sky, which took about two years. TESS is now beginning an extended mission where it will cover a similar pattern of nearly the whole sky, but offset somewhat to cover the gaps in coverage missed the first time around. Some of the most interesting planets in the catalog are: a planet called TOI 700 d that is Earth-sized and orbits in its star’s habitable zone; one called TOI 1338 b, the first planet found orbiting a pair of stars; LHS 3844 b, a large rocky planet that orbits so close to its star that its year is only 11 hours long; and TOI 1690 b, which survived its star swelling to a red giant and then collapsing to a white dwarf.

Brown Dwarf Speed Limit – Brown dwarfs are stars that don’t have enough mass to sustain the hydrogen fusion that powers ordinary stars. Strangely they speed up their rotation as they age. This is caused by contraction as they cool combined with the conservation of momentum, and sustained because they have nearly zero friction as they rotate. A new study by researchers at the University of Western Ontario of brown dwarf rotation speeds has found no such objects with rotation periods less than one hour. Apparently there is a limit to brown dwarf rotation speed. Theorists have yet to explain what causes this limit.

Cosmic Ray Sources – Finding the source of cosmic rays with detectors on Earth is difficult, because the cosmic ray particles collide with molecules in Earth’s atmosphere and never reach the surface. They cause a shower of struck atmospheric particles, but even tracing these back doesn’t indicate the source. This is because cosmic rays are charged particles that deflect every time they encounter magnetic fields on their trip from their cosmic source to Earth. Scientists figured out that cosmic rays that collide with interstellar atomic nuclei near their source produce gamma rays that are undeflected by later-encountered magnetic fields, and so can be used to trace cosmic rays back to their source. These gamma rays are also stopped by Earth’s atmosphere, causing showers of similarly struck atmospheric particles that look much like cosmic-ray showers, except that cosmic-ray showers contain lots of muons, and gamma-ray showers have few muons. On the high elevation of the Tibetan Plateau, scientists built an array of atmospheric particle shower detectors, along with muon detectors, and a supercomputer that traces the atmospheric showers back to their sources in the sky. They discard the ones with large numbers of accompanying muons (which is most of the showers), to pinpoint the sources of the cosmic rays that produced gamma rays. Results from this system, known as the Tibet ASγ Collaboration, showed that the majority of high-energy cosmic rays have sources in the plane of the Milky Way, so must be originating in our galaxy. But some of these signals originated from other directions, likely distant galaxies. These tend to have higher energies than Milky Way cosmic rays, suggesting that there may be two different mechanisms to produce high-energy cosmic rays.

Earth’s Core – Researchers at the Australian National University announced that the inner core of the Earth is actually two layers with different properties, perhaps due to a change in the structure of iron at higher temperature or pressure. This now means the layers of Earth are: crust, mantle, outer core, inner core (outer part), and inner core (inner part).

Crew Launch – In late April, four astronauts launched to the International Space Station aboard a SpaceX Crew Dragon capsule atop a Falcon 9 rocket. This brings the total to 10 for the number of astronauts launched into space on a privately developed rocket. Both the capsule and the rocket first stage were reused from previous flights (or as SpaceX likes to call them, flight-proven, rather than reused).