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

Physics Nobel Prize – Because the Nobel Prizes do not have a category strictly for astronomy, astronomers whose work merits the honor are awarded the Physics Nobel. Three astronomers received the 2019 Physics award. James Peebles was recognized for his theoretical work on the cosmic microwave background (CMB) and cosmology. He was one of the first to predict that the Big Bang had to have produced the CMB, and he went on to show what scientists could learn about the early Universe from the properties of the CMB. His prediction of the CMB came in a paper he had written but not yet published by the time that Arno Penzias and Robert Wilson discovered the CMB, who received the 1978 Physics Nobel for the discovery. Peebles’ later theoretical work showed that the observed CMB properties imply that there is dark matter and dark energy. This award is perhaps for the most theoretical work ever, rather than for discovery. The prize was shared with Peebles by Michel Mayor and Didier Queloz for their discovery in 1995 of the first planet outside the Solar System which orbits a Sun-like star. The only previously known exoplanets orbit a neutron star, and such are still rarities. Mayor and Queloz’s first planet is 51 Peg b, a gas giant orbiting a naked-eye visible star 50 light-years away in the constellation of Pegasus. Since then, thousands of planets orbiting Sun-like stars have been found. Mayor and Queloz opened the door to exoplanet astronomy. 51 Peg b was found by the radial velocity method, where wobbles in the spectral lines of a star fit the pattern of what is caused by the gravitational attraction of an orbiting planet that changes the position of the star as it orbits.

All-Female Space Walk – NASA Astronauts Jessica Meir and Christina Koch performed the first all-female spacewalk on October 18. Lasting more than seven hours, the two replaced a battery charge/discharge unit that failed to activate on recently installed lithium-ion batteries. It’s the 221st spacewalk in support of the construction of the station. A previous all-female spacewalk had been scheduled for March but a last-minute personnel change had to be made due to the unavailability of properly fitting and configured space suits. Koch has been aboard the ISS since March and walked in space shortly after arriving, while Meir had only arrived on September 29 and it was her first spacewalk. Both Meir and Koch were members of the 2013 astronaut class which was 50 percent women. The extravehicular work was a success and the batteries are working properly now, helping to power the space station.

Alexei Leonov – Soviet cosmonaut Alexei Leonov died in Moscow at age 85. He was a renowned pioneer and hero in exploring space. He made history in 1965 while on the USSR’s Voskhod 2 mission he left his space capsule and became the first person to “walk” in space. It nearly ended in disaster when his spacesuit swelled from the pressure and he was unable to fit back into the spacecraft. Only by dangerously lowering the pressure in his suit was he was able to fit through the hatch and reenter his craft. The mission landed off course, and Leonov and fellow cosmonaut Pavel Belyayev endured two freezing nights in the wilderness before they skied out with a rescue party. Leonov also flew the Apollo-Soyuz joint American-Soviet mission in 1975. Years later, he and American astronaut David Scott jointly wrote a book telling the history of the space race from both sides. He was also an artist and is credited with making the first artwork in space, a sketch of sunrise from orbit made on the Voskhod 2 mission.

Cosmic Web – The Universe is permeated by a cosmic web of gas connecting galaxy clusters. Though ubiquitous, it has proved extremely difficult to image, since it is so sparse and emits or reflects little light. However, light that does pass through a segment of it is imprinted with a spectral trace of the web’s material, but can’t actually produce an image of the web. Astronomers have taken what may be the best image yet of the cosmic web in a small area of the sky where the web is so distant that the light left there a mere two billion years after the Big Bang. The reason this piece of web is visible is that it is being illuminated by nearby galaxies that are undergoing bursts of star formation and/or black hole activity. The images were taken with the Very Large Telescope in Chile. Two filaments of web can be seen that are about three million light-years long. The light illuminating the web is actually ultraviolet light, but it is shifted to visible light or infrared by the expansion of the Universe. Since ground based telescopes can’t observe ultraviolet, this technique does not work on closer parts of the cosmic web since light from close objects does not get shifted to visible light or infrared by expansion. A large ultraviolet space telescope would be required to observe nearby sections of cosmic web, but that has not happened yet.

Galaxy Halos – The halos of hot rarified gas that envelop most massive galaxies have proved difficult to detect or study but astronomers recently found a new method. Up until recently, they’ve observed the effects the halos have on the light emitted by distant quasars that passes through on its way to planet Earth. Now, the effects of a halo can also be seen on radio waves from fast radio bursts (FRBs). By analyzing the amount that different frequencies within the FRB are delayed while passing through the halo, some properties of the halo gas can be determined. Though so far this has only been observed once, astronomers hope to see it more frequently in the future. From this first such observation they were able to determine that the observed burst traveled 95,000 light-years from a foreground galaxy on its way to Earth and that the halo is surprisingly thin and lacks turbulence or any substantial magnetic field. The one downside to this method is astronomers don’t get to choose a particular galaxy halo with this method, since FRBs occur at random times and places all over the sky.

Gravitational Lens For X-rays – Huge concentrations of mass, such as clusters of galaxies, can bend light and act as a gravitational lens, magnifying and brightening objects behind them. This has been used for years to see in visible light detail of distant objects that would be too small or dim to see without lensing. For the first time, astronomers announced that they’ve been able to do this using X-rays. They first characterized the X-ray image of the foreground object and subtracted it out to image a dwarf galaxy behind the Phoenix galaxy cluster. The magnification, which is about 60 times, allowed the astronomers to distinguish two very active star-forming regions in the distant dwarf galaxy, one brighter than the other, apparently because it has younger brighter stars. The light from the distant dwarf galaxy took about 9.4 billion years to reach us, while the Phoenix Cluster’s light took a mere 5.7 billion years.

Triple Black Hole – A triple supermassive black hole has been discovered. Known as SDSS J084905.51+111447.2, a catalog number from the Sloan Digital Sky Survey, it is about a billion light-years away. It was confirmed using observations in visible light, X-rays and infrared from ground-based and space-based telescopes. The black holes are located at the centers of three colliding galaxies. They are expected to eventually merge into one even more massive black hole. Known double and triple supermassive black holes are rare, yet collisions of galaxies are not very unusual. Each collision should produce, for a time, a double (or more) supermassive black hole, so likely most double or triples are hidden in dust or gas clouds.

Counter-rotating Disks – New observations of galaxy M77 using, ALMA, a radiotelescope array in Chile, show that the supermassive black hole at its center has not one, but two accretion disks about it. Even more surprising, they are rotating in opposite directions. The inner disk is between two and four light-years out and is rotating in the same direction as the black hole spins. The outer disk stretches from four to 22 light-years out and rotates the opposite way. Astronomers involved proposed that the opposite-rotating disk could have been caused by gas clouds that fell in or by a small passing galaxy. It is believed that counter-rotating disks will cause material to fall into the black hole faster than single-rotation. This may be the answer as to how many supermassive black holes grew to huge masses very quickly in the early history of the Universe.

Speedy Hot Jupiter – An exoplanet has been discovered by a transit survey located in Chile, and that planet has the shortest known orbital period around its star of any hot Jupiter: a year of only 18 hours. Gas giant planets that orbit close enough to their star to be significantly heated by the star, such as this one, are known as hot Jupiters. Though an 18 hours might seem to be a fast year, the fastest overall is a rocky planet known to have an even shorter year. This hot Jupiter is located about 1000 light-years away, and is known as NGTS-10b. The planet is about twice the mass of Jupiter, but nearly the same diameter. Planets quite close to their stars should have tidal forces that slowly shrink the orbit, eventually tearing the planet apart, with the pieces falling into the star. Astronomers will study this planet to see if they can detect signs of orbital shrinkage, in order to verify that theory. Estimates are that it will take 38 million years for this planet to be consumed by its star.

Tidal Disruption Event – A supernova survey known as ASASSN spotted a galaxy whose core suddenly brightened, and further observations showed that the galaxy’s central black hole is tearing apart a star and consuming it. This is known as a tidal disruption event or TDE. This is now the best observed TDE yet. Astronomers hope to learn the details of TDEs from these observations.

Saturn Moons – Astronomers announced the discovery of 20 more moons orbiting Saturn. This is based on observations made with the 8-meter Subaru Telescope in Hawaii. This telescope has a very wide field of view, and was able to capture dim objects orbiting far from the planet. The 20 are each about 3 miles in diameter, near the limit for objects at Saturn’s distance that can be seen with this size of scope. Of the 20 new moons 17 of them are in retrograde orbits, revolving around the planet in the opposite direction of its rotation. These moons were likely captured by the planet’s gravity rather than forming with the planet, which is why they’re in these distant retrograde orbits. All of the 20 moons take about two to three Earth years to orbit the planet. The moons belong to three different previously-established moon groups. Each group is believed to consist of the shattered remnants of a larger moon that broke up some time in the distant past, as members of any one group have similar orbits. Saturn is now the king of moons, having 82 known natural satellites, surpassing of Jupiter, which formerly held the record with 79 known moons.

Martian Climate – As the Mars rover, Curiosity, climbed up from the lower parts of Gale Crater, it saw rocks shift from ones formed in an ancient fresh water lake to rocks formed in evaporating salty ponds. It also recently discovered cracks in a Martian rock that may have formed when a mud layer dried out. A nearby area contained deposits of various kinds of salt mixed with sediment. The best estimate for this evaporating period is that it occurred 3.3-3.7 billion years ago. This is helping to pin down when Mars transitioned from a warm wet planet to a cold dry one.

Marsquakes – The seismograph on the Mars InSight lander has, since it was deployed last December, detected more than 100 shakings. Though most are non-quake disturbances of some kinds, including wind gusts, 21 have been identified as having characteristics of marsquakes. Moonquakes and earthquakes differ in characteristics, in part because cracks in the Earth’s crust are water filled and moon cracks are not. The 21 marsquakes have characteristics of both but are slightly more Moon-like. The frequency of small marsquakes (under magnitude 3.5) has been about what was expected, but there are fewer than predicted for larger quakes. Scientists don’t yet know why that is.

InSight – Speaking of InSight, its heat probe, designed to pound itself up to five yards deep into the ground to measure the heat escaping from the core of Mars, is still stuck just over a foot into the Martian ground. Spacecraft controllers have a couple of plans: use the spacecraft arm to press soil against the probe to increase friction with the ground, and use the arm to pour loose soil into the hole also to increase friction. They believe that a lack of friction with the ground is causing the probe to bounce back after every stroke pounding it down. The first plan was tried and movement of the probe by about three-quarters of an inch was observed, hopefully meaning that pounding can resume. The probe must reach two to three yards deep to get meaningful data.

Loki – Loki is a huge pool of magma on Jupiter’s moon Io about 120 miles across. Up until the year 2000, Loki brightened and dimmed in a fairly regular period of about 540 days, akin to some volcanoes on Earth. It is caused by the surface cooling and solidifying, then sinking and repeating. Then in 2000 Loki stopped the brightenings. Since 2013 Loki has been oscillating in brightness again, but this time with a period of about 475 days. Observations will continue to figure out why.

Merging Black Holes – The teams running the gravitational wave detectors LIGO and VIRGO have previously announced 11 certain detections of merging black holes from their first two observing runs, and 33 candidates for detections from its current run. The raw data from their first two runs has been made public. Scientists not associated with LIGO or VIRGO have developed computer algorithms that claim to better separate noise from data and applied them to the public data. One team has announced seven more instances they found in the data that they believe are gravitational waves from merging black holes. The black holes had masses similar to those of previously announced mergers, about 20-40 times the Sun’s mass. Two of the seven show unusual spin properties, and will prompt further analysis.