DESI – The Dark Energy Spectroscopic Instrument (DESI) is only about 10 percent of the way through its five-year operation, but its team, led by astronomers at Lawrence Berkeley National Laboratory, has already produced the largest ever three-dimensional map of the Universe. DESI is a multi-object spectrograph mounted on the four-meter Mayall telescope on Kitt Peak in Arizona. Each spectra is captured using a separate optical fiber connected to the focal plane of the telescope. The receiving end of each optical fiber is placed by computer control to the location of a galaxy or quasar. DESI can capture up to 5,000 spectra at once. Each object’s distance is measured by its redshift taken with the spectrograph. It takes less than two minutes to configure the fibers for the next observation. The positions for configuring are taken from a previous imaging survey. The goal is to observe about a third of the entire sky, with an expected 35 million galaxies and 2.4 million quasars. This will allow astronomers to put together a history of the expansion of the Universe.
Isolated Black Hole Discovered – An international team of astronomers discovered a stellar-mass black hole that isn’t part of a multiple-star system. The team found the black hole by looking for the apparent brightening and warping of a distant star as a massive object passing in front of it bent its light, a relativistic effect known as microlensing. The Hubble Space Telescope together with ground-based telescopes observed the lensing over a period of months. The mass of the foreground object is about seven times the mass of the Sun, and emitted no detectable light, ruling out objects other than a black hole. Its distance is about 5,000 light-years.
Black Hole Flares – Until recently, computer simulations have been unable to correctly simulate black holes that emit flares as material falls in. Now, a new computer model by researchers at the Flatiron Institute has finally produced the flares by working at far finer resolution. Magnetic field lines breaking and reconnecting near the black hole’s event horizon start the process. That magnetic energy propels hot plasma to near-light speeds, which radiate photons of light that make up the observed flares. These flares can clear material near the event horizon, until more material falls in and repeats the process.
Mystery Radio Object – A team of radio astronomers at the International Centre for Radio Astronomy Research observed an object that emits huge, one-minute bursts of energy three times an hour. No known astronomical object bursts in this time range. Their best guess is that it is a neutron star or possibly white dwarf with a strong magnetic field, but with a unique rotation rate. The strong magnetic field is implied by the observed high polarization in the radio signal. The object is about 4,000 light-years away. Since its initial detection, the object has since switched off, but it is being monitored to see if the radio bursts return.
Exoplanet Atmosphere – A team of scientists at the University of Bern analyzed the atmosphere of an extreme exoplanet. It is a “hot Jupiter,” a gas giant so close to its star that it is broiling, in this case about 5,800 degrees Fahrenheit. The CHEOPS space telescope and the La Silla Observatory in Chile made the observations. The planet is known as WASP-189b and is 322 light-years away. The atmosphere contains layers of differing properties, and contains vapors of iron, chromium, vanadium, magnesium and manganese. Also found is titanium oxide, which absorbs ultraviolet light similarly to how ozone does this in Earth’s atmosphere.
Warped Exoplanet – WASP-103b is an exoplanet that orbits so close to its star that its year is only 22 hours long. New analysis by astronomers at the University of Porto shows that its proximity to its star has gravitationally warped the planet’s shape to roughly that of a rugby ball. The team analyzed multiple transits that blocked a portion of its star’s light, as seen by three space telescopes: CHEOPS, Hubble and Spitzer. The shape allows scientists to calculate the rigidity of the planet, and it is similar to that of Jupiter. This was a surprise, because 103b’s mass, 50 percent larger than Jupiter, should have increased its rigidity. Possibly heating from its star prevented additional rigidity. Another surprise is that 103b is slowly expanding its orbit, even though tidal forces on a closely orbiting planet should cause its orbit to shrink.
Possible White Dwarf Planet – Using ground- and space-based observations, astronomers at University College London found evenly spaced clouds of planetary debris in a ring around a white dwarf star 117 light-years away. Such a structure would not remain stable unless there is a nearby planet gravitationally influencing it. The structure is in the region that was once engulfed by the star when it expanded during its red giant phase, indicating that the structure formed at or moved to its present location after the red giant phase shrunk to the white dwarf phase. More observational evidence is needed to confirm that there is a planet near the ring.
Another Proxima Planet – A team of astronomers from the University of Porto used the Very Large Telescope in Chile to discover the third exoplanet orbiting Proxima Centauri, the nearest star to our Sun. The planet, known as Proxima d, orbits about 10 times closer to its star than Mercury orbits the Sun. It takes only five Earth days to complete each orbit. This is too close to be in the habitable zone where temperatures would allow liquid water to exist on a planet. It is just a quarter the mass of the Earth, making it the least massive exoplanet ever found using the radial velocity method of detection. The previously known planets orbiting Proxima take 11 Earth days and five Earth years to complete their orbits.
Quadruple Stars – The TESS space telescope’s regular job is looking for exoplanets by detecting the slight dimming of their stars when the planet transits in front. But it is also good at finding multiple star systems when one star transits its companion star. The TESS team at NASA’s Goddard Space Flight Center found 97 quadruple star systems, nearly doubling the number known, though these are only quadruple star candidates until confirmed by other observations. Volunteer citizen scientists helped in discovering the quadruples. The team found other kinds of multiple star systems, including the first known sextuply-eclipsing sextuple system.
Widely Separated Brown Dwarfs – A team led by astronomers at Arizona State University discovered a pair of brown dwarfs orbiting each other at the farthest separation of any such pair known. They are about three times the separation of Pluto from the Sun. Because brown dwarfs are less massive than ordinary stars, it is unusual for brown dwarf’s gravity to hold pairs of them together at great distances. The pair is known as CWISE J014611.20-050850.0AB and is about 130 light-years from Earth. The WISE infrared space telescope discovered the object, but it was thought to be a single brown dwarf until other observations showed it was double.
Martian Past Climate – There is much evidence that water flowed on Mars and that a northern ocean existed about three billion years ago. How long these conditions persisted has long been debated. A new study by researchers at the University Paris-Saclay and NASA Goddard Institute for Space Studies simulated atmospheric and surface conditions on Mars and showed that water could have remained liquid for 500 million years longer than previously thought, even though temperatures became fairly cold. The computer simulation showed that rainfall, rather than snow, would persist in the area of the northern ocean and that ocean circulation would help prevent the ocean from freezing. This would greatly expand the time that the Martian climate might have been hospitable to life. An atmosphere with a bit of hydrogen, in addition to the carbon dioxide that now remains, would have warmed Mars and contributed to the lengthening of time with a liquid-water climate. The simulation showed that the Martian southern highlands would freeze long before the low-lying northern regions. Another study, by researchers at Caltech using images from the Mars Reconnaissance Orbiter, found salt deposits left by liquid water that dried up. They dated these deposits using crater counts to having formed as late as two billion years ago, further extending the time of liquid water on Mars.
Saturn’s Aurora – A team of scientists from the University of Leicester found that winds cause of some of Saturn’s aurora, a different process than other planets in our Solar System. Most aurora is caused by powerful currents flowing down from the planet’s surrounding magnetic field. These Saturnian winds also cause movement in Saturn’s magnetic field. This finally explains why measurements of the rotation rate of Saturn’s magnetic field keep getting slightly different rates over the years. The other planets of the Solar System show rotation rates of the magnetic field that exactly match the rotation of the bulk of the planet’s mass.
Comet Lunar Material – Scientists at the Southwest Research Institute took another look at data captured in 2009 when the LCROSS lunar mission intentionally crashed a spent Centaur rocket into a crater near the Moon’s south pole to analyze the material splashed up. The team found that the splashed material was not volcanic, but probably material left by a comet impact. This was based on ratios of various elements seen in spectra of the splash. The lack of sunlight and solar wind near the pole preserved material there even though the impact may have been long ago.
Earth Trojan Asteroid – Most Trojan asteroids share Jupiter’s orbit, where thousands lead and trail the planet by about a 60-degree angle in the L4 and L5 gravitationally stable Lagrange points. However, other planets in our Solar System have Trojan asteroids as well, but in far smaller numbers. Earth had just one known, but a team at the University of Alicante discovered a second. Designated 2020 XL5, it is roughly 0.6 mile across. Computer simulations of its future position show that it will be gravitationally knocked out of the L4 Lagrange point area in about 4,000 years. The eccentricity and tilt of XL5’s orbit likely contribute to this instability. This also means it probably did not form near the Lagrange point, but was captured in astronomically recent times. Any Trojan asteroid that has remained in its orbit since formation would be a good subject for a spacecraft visit, since its composition would tell scientists what the conditions were at that distance from the Sun during the time of planetary formation.
Asteroid Discoveries – A team of astronomers at the Max Planck Institute of Extraterrestrial Physics and the Autonomous University of Madrid invited the public to become citizen scientists and search through thousands of archived images from the Hubble Space Telescope to find asteroids that may have snuck into frame. The streaks from asteroids had to be distinguished from streaks of other origin, such as cosmic rays or satellites. The public found more than 1,400 “photobombing” asteroids. The astronomers then trained a computer program to distinguish asteroid streaks by learning from the citizen scientists’ classifications of streaks in more than 30,000 images. This program then searched through more Hubble images and identified about another 1,000 asteroid streaks. An examination of these asteroid streaks by astronomers validated 1,701 streaks as being definitely asteroids. Of these, 670 were found to be known asteroids, and the remaining 1,031 are now new discoveries, though they will not go into the official asteroid database unless and until orbits can be calculated. The streaks themselves can be used to study size and distance statistics of asteroids.
Quadruple Asteroid – New data reduction methods developed by researchers at the National Astronomical Research Institute of Thailand, and applied to old data showed another moon orbiting the asteroid Elektra, making a total of three moons there. This is the only known quadruple asteroid. The estimated period of the moon is about 16 hours and its average distance from Elektra about 200 miles, with a somewhat elliptical and tilted orbit. Its size is estimated from its brightness to be one mile across.
Youngest Asteroid (or Comet) Pair – The asteroids 2019 PR2 and 2019 QR6 have similar orbits, and are believed to be fragments of a larger asteroid that broke apart. There are many such fragments known and often their paths can be traced back to when they were at the same place yielding the time of the fragmentation. Recently this pair was traced back by researchers at the Czech Academy of Sciences and found to have fragmented only about 300 years ago, making them the youngest such pair known. The previous record holder was at least 10 times this age. The larger of the pair is about 0.6 mile across, and the other about half that. They also have similar surface properties, again supporting that they are fragments of the same body. Scientists think that most fragmenting asteroids do so because they spin up too fast and fly apart. Collisions can also create fragmentation, but probably much less frequently. Simulations of the newly discovered young pair did not match their current separation, but simulations of a fragmenting comet do fit. However, it remains to be explained why these asteroids are not outgassing, as comets should.
Dark Features in Solar Flares – Since 1999, solar astronomers have occasionally seen dark features descending within flares rising from our Sun. A team of scientists at the Harvard Smithsonian Center for Astrophysics analyzed downflowing features in images from NASA’s Solar Dynamics Observatory. That spacecraft takes five solar images every minute in seven wavelengths of light. They found that contrary to previous theory, the dark downflows are not related to magnetic reconnection events, but instead are caused by fluids of different densities interacting. They are actually voids in the hot material of the flares.
Comet Tail – The ESA’s Solar Orbiter spacecraft has, for the second time, flown through the tail of a comet. This time it was Comet 2021 A1 Leonard, and the previous time was Comet 2019 Y4 ATLAS. Both encounters were predicted in advance so mission controllers commanded the spacecraft to take observations relevant to a comet. The new observations detected ions of oxygen, carbon, nitrogen, carbon dioxide, carbon monoxide and possibly water. These ions were of cometary origin, because ions from the Sun would have higher charge than seen. Also observed were the comet’s effects on the solar magnetic field. SOHO, STEREO-A and Parker solar spacecraft were commanded to observe from a distance Leonard’s tail simultaneously with Solar Orbiter’s observations.
Solar Storm – An analysis by researchers at Lund University of ice cores from Antarctica and Greenland show that there was a powerful solar storm 9,200 years ago. Such storms produce high-energy particles that generate the isotopes beryllium-10 and chlorine-36, which remained in the ice cores. It is puzzling that the storm took place in a quiet stretch of solar activity, rather than at active times, when powerful solar storms seem more common.
Satellite Constellations – The International Astronomical Union established a Centre to protect the dark sky from satellite constellations. The Centre will be hosted by the SKA Observatory in Australia and South Africa and the NOIRLab in Arizona. The purpose is to unite radio and optical astronomers to address the owners of satellite constellations to try to reduce those satellites’ ill effects on astronomy and the night sky for humanity and wildlife.
Private Space Mission – The company Axiom Space has been given the go-ahead to send a privately organized mission to the International Space Station in late March. The four astronauts will launch aboard a SpaceX Falcon 9 rocket and Dragon spacecraft. They will spend eight days at the Station and perform scientific, educational and commercial activities. They trained at NASA, ESA (European Space Agency) and SpaceX. The mission commander is a former NASA astronaut, Michael López-Alegría.
Near-Earth Object Search Expands – University of Hawaiʻi’s ATLAS program has been using two 20-inch wide-field telescopes in Hawaii to search for near-Earth objects, particularly hazardous ones, since 2015. The program has discovered 727 near-Earth asteroids and 66 comets, as well as over 10,000 supernovas. Now ATLAS has expanded its reach by adding similar telescopes in South Africa and Chile and can now search skies farther south and when it is daytime at the Hawaii telescopes.