James Webb Space Telescope Launched – Shortly after noon local time, December 25, the Ariane 5 rocket carrying the James Webb Space Telescope lifted off from the Guiana Space Centre in French Guyana. The infrared telescope is now starting its month-long journey towards its ultimate home, orbiting Earth’s L2 Lagrange point, about a million miles away. As it travels, the telescope’s distinctive eighteen hexagonal mirrors and diamond-shaped sunshields unfurl like a flower, which have so far gone off largely without a hitch. The JWST’s primary mirror is significantly larger than that of the Hubble Space Telescope, and the instrument is designed to observe wavelengths of light in the near and mid infrared. The project has taken 25 years and about $9 billion to build and is designed to operate for ten years.
Mars Helicopter – Ingenuity, the Mars helicopter, completed its seventeenth flight in early December. There were tense moments as it landed, because it lost radio contact with the rover Perseverance, which relays all helicopter radio communication to Earth. Controllers had not realized that a rise in the terrain would block the radio line-of-sight. Contact established a few days later showed the landing had been perfect. Current Mars flight records: 30 minutes total flying time, 2.2 miles total flying distance, 40 feet highest altitude, and 10 mph highest speed.
Mars’s Subsurface Properties – Scientists at ETH Zurich and the University of Cologne analyzed seismic data from the Mars lander InSight to determine the structure of the ground under InSight’s landing region, the area known as Elysium Planitia. The seismic vibrations were caused by wind. The analysis showed a sandy surface layer about three meters deep, then about 15 meters deep of blocky material thrown out from impacts known as ejecta, followed by about 150 meters of basaltic rocks formed from lava with a sedimentary layer between lava flows. Counting impact craters in the lava flows determined that shallower lava flows were 1.7 billion years old, and deeper lava is 3.6 billion years old. The data were able to reveal structures to about 200 meters below the surface.
Probable Martian Ice – The Trace Gas Orbiter (TGO), a part of the European ExoMars missions, has discovered large amounts of water or ice in the bottom of Mars’s Valles Marineris huge canyon system. Large deposits of Martian water or ice have previously been found near the poles or below the surface of mid-latitudes, not nearly as close to the equator as Valles Marineris. The TGO instrument used finds hydrogen-containing material within about a meter of the surface by detecting neutrons given off when cosmic rays strike the ground. The newly found water-rich region is about the size of the Netherlands. It is not clear whether the water detected is in the form of ice mixed with the soil or water chemically bound to the minerals of the soil, though experts have said it is likely ice. Conditions near the equator tend to evaporate ice close to the surface, so scientists need to explain how Valles Marineris conditions protect the ice from loss, or how loss is replenished.
Pluto Polygons – A new study by researchers at the University of Exeter explains how the polygonal areas on Pluto formed. These shapes, typically 12 miles across, are found in Sputnik Planitia, an impact crater filled with nitrogen ice. Previous analysis claimed that heat flowing from the interior caused convection (rising of material due to temperature difference) which broke up the nitrogen ice into the polygons, but the new study showed the convection is driven by cooling of the surface caused by sublimation, where the solid surface evaporates directly to gas without involving liquid. Computer simulations of the planet were run for the new study, and they best matched the reality on Pluto when sublimation cooling was the driver of convection.
Pristine Asteroid Material – An analysis by scientists at the Japan Aerospace Exploration Agency of the material brought back from the carbon-rich asteroid Ryugu by the spacecraft Hayabusa 2 shows that it is the most primitive Solar System material yet seen. It contains hydrated materials and organic material that appear never to have been heated since they formed during the formation of our Solar System. Material like this is probably present in some primitive meteoroids, but is destroyed by high-speed passage through our atmosphere, so is not seen in meteorites. The grain size of the primitive material ranges from dust to about a third of an inch. It is quite dark, reflecting only 2 percent of visible or near-infrared light. It is extremely porous, having density less than any meteorites. There are no round grains known as chondrules which are often found in meteorites.
Fastest Exoplanet Revolution – Astronomers at MIT discovered an exoplanet that orbits about its star in only 16 hours, making it the shortest known year of any gas giant planet. The planet is named TOI-2109b, was found by the TESS planet-finding space telescope, has a mass about five times that of Jupiter, and is about 855 light-years away. It is extremely hot due to its proximity to its star, and its dayside temperature is estimated above 3,500 degrees Fahrenheit. The planet is slowly spiraling into its star, shortening its period by a fraction of a second every Earth year. So it would be continuously setting the record for shortest exoplanet year, except …
Yet Faster Exoplanet Revolution – Shortly after the above discovery, astronomers at MIT found an exoplanet, dubbed GJ 367b, that orbits its star in just eight hours. However this newer discovery appears to be an iron planet, due to its high density, so TOI-2109b still holds the record for a gas giant. GJ 367b is about 60 times closer to its star, a red dwarf, than Mercury is to our Sun. The system is 31 light-years away. The planet is a bit larger in diameter than Mars, but five times as massive, resulting in a huge density. The planet was discovered by the transit method, but was subsequently detected also by the radial velocity method, which allowed its mass to be measured. Its surface temperature is estimated at 2,700 degrees Fahrenheit and likely has molten lava on its surface. It is possible that when it formed it was more Earth-like, but almost all of it, save for its iron core boiled away from the heat. Astronomers plan to look for other planets at this star, hoping to learn how this planet ended up so close to its star.
Exoplanet Composition – When a white dwarf star forms at the end of the life of a Sun-like star, it ends up with a thin atmosphere of just hydrogen and helium, unless some of its orbiting planets fell in and polluted the hydrogen and helium. Scientists at the National Science Foundation’s NOIRlab and California State University made a study of 23 such polluted white dwarfs to see what their inner planets were made of. What they found were more exotic materials than the silicates, iron and other materials found in the inner planets of our Solar System. Only one of the white dwarfs appeared to have consumed a planet of Earth-like composition. This may be an indication that our Solar System is not typical.
Inclined Orbits – Planets coalesce in a disk of material orbiting around a forming star and because they form together, the disk and the star’s rotating equator should be aligned on the same plane. A new study by astronomers at the University of Geneva of the star HD 3167, located 150 light-years distant, found two of its three known planets orbit almost perpendicularly to the star’s equator and steeply inclined to the other planet. The astronomers determined the planes of the planets’ orbits by measuring how the spectrum of the Doppler shift from the rotation of their parent star appeared to change as the planets passed in front of it. The best hypothesis for how these planets ended up in unexpected orbits is that there is a massive planet in the system, as yet undetected, whose gravity has been perturbing orbits. The known planets of the system are, from small to large orbits, a super-Earth and two mini-Neptunes. Astronomers hope that further observations will establish how elliptical their orbits are because highly elliptical orbits are often caused by gravitational perturbations.
Validating Exoplanets – Scientists at NASA’s Jet Propulsion Lab trained a machine-learning computer program called ExoMiner to hunt for exoplanets using data from thousands of exoplanet transits, some verified, and others known false alarms. They then told it to find the real exoplanets among thousands of planet candidate transits observed by the Kepler space telescope. The program identified 301 exoplanets that it was sure were real, adding to the more than 4,500 exoplanets validated by other means. The scientists plan to run ExoMiner on TESS transit data and other future planet-finding space telescope missions.
Extreme Exoplanet – A group of astronomers at Stockholm University and the Max Planck Institute for Astronomy took an image of an exoplanet orbiting b Centauri, a 4th magnitude binary star about 325 light-years away (not to be confused with Beta Centauri, which is much brighter as seen in our sky). It is the hottest and most massive star known to have a planet. The planet orbits 560 times as far from its star as Earth is from the Sun. All these are extremes not expected of any planet. Together, the binary star pair has at least six times the mass of our Sun, and is only 15 million years old. Scientists had thought that extreme ultraviolet and X-ray radiation from such a massive star would disrupt planet formation, but this planet indicates otherwise. Perhaps its great distance from its star could explain its existence. It is a very massive planet at about 11 times Jupiter’s mass. The image of it was taken with the SPHERE instrument on the Very Large Telescope in Chile. SPHERE uses adaptive optics and a coronagraph to block the star’s light from overwhelming the planet’s light. After discovery, an image of the planet was found in archived images over 20 years old taken by a 3.6-meter telescope in Chile. Previous planet imaging searches have tended to ignore such massive stars, so the discoverers of this planet are wondering if there are many planets waiting to be discovered if massive stars are searched.
Battered White Dwarf Companion – White dwarf stars typically emit low-energy X-rays, but recently three white dwarfs were caught brightly emitting high-energy X-rays. An international team investigated and found that one of them, a star known as KPD 0005+5106, was regularly cycling in X-ray brightness every 4.7 hours. This indicated something was orbiting about it, perhaps a planet or a very low-mass star. Material from the orbiting object is being pulled onto the white dwarf, and where the material strikes the star it creates a hot spot that glows in X-rays. That spot periodically goes out of view, causing the cycling X-ray brightness. Though a search was made in visible light, the orbiting object has not been found. If the orbiting object is anything brighter than the dimmest of stars, it would have been seen. The white dwarf is about 1,300 light-years away, and is one of the hottest known white dwarfs. To have a 4.7 hour orbital period, the object must be 30 times closer to its star than Mercury is to our Sun. This proximity results in the object being blasted by radiation, and its material gravitationally stripped by the white dwarf.
Milky Way’s Black Hole Weighed – By combining the light of all four Very Large Telescopes in Chile, using interferometry, astronomers at the Max Planck Institute for Extraterrestrial Physics produced the highest resolution, most sensitive images ever of the center of our Milky Way galaxy. A star, dubbed S300, was discovered in the images quite close to the supermassive black hole there. By tracking this star’s motion, the mass of the black hole was calculated more precisely than ever before: 4.30 million times the Sun’s mass. The observations, combined with further observations from the Keck and Gemini Telescopes, confirmed that the motions of the stars near the black hole were conforming to Einstein’s General Relativity extremely precisely and the distance to the black hole was measured to be 27,000 light-years.
Magnetic Propeller Star – The second known magnetic propeller star has been discovered by astronomers at the Universities of Sheffield and Warwick. Magnetic propeller stars are white dwarfs with strong magnetic fields rotating extremely fast that gravitationally draws material from a nearby companion star, then flings it out magnetically at about 2,000 miles per second. The new discovery is known as LAMOST J024048.51+195226.9, is about the diameter of Earth, but roughly the mass of a Sun-like star and rotates every 25 seconds.
Powerful Ejection – Observations by astronomers at the National Astronomical Observatory of Japan, of the star EK Draconis, caught a massive coronal mass ejection, much more powerful than any seen from our Sun. The star is roughly the mass of our Sun, but probably much younger. Some astronomers have questioned whether such powerful ejections are possible with stars as old as our Sun, as such could be quite damaging to Earth.
Cow explained – Flashes in the night, more formally known as astronomical transients, are given consecutive identifiers ending in three letters starting at the first of each year. One such transient that has resisted classification or explanation was AT2018cow, shortened to “the Cow.” It was much too bright to be a supernova, and didn’t match the rise and fall times of a supernova. Follow-up observations found that the Cow was emitting regular pulses of X-rays every 4.4 milliseconds, which continued for a couple of months. A new study by researchers at MIT based on the X-ray observations claims that the transient was caused by a star collapsing into either a neutron star or a black hole, and that material kept falling into it after the collapse, adding much more brightness than an ordinary star-collapse supernova. The study ruled out other proposed explanations. The periodic X-ray emission is likely from a fast spinning accretion disk. X-ray data was provided by NICER, an X-ray telescope on the International Space Station. The Cow was seen in the galaxy CGCG137-068, which is about 200 million-light years away in Hercules. It is being classified as a “fast blue optical transient” or FBOT, which is a catch-all of unexplained blue transients. This is the only one of several FBOTs that has been caught immediately and follow-up observations made.
Closest Supermassive Black Hole Pair – Astronomers at the University of Queensland have discovered in the galaxy NGC 7727 a pair of supermassive black holes that is the closest known such pair to us at 89 million light-years distant. They are the closest to each other of any known such pair and will merge into one large black hole in about 250 million years. The masses of the black holes, determined by star motions about them, are 154 million and 6.3 million Sun’s masses.
Strange Galaxy – Astronomers at University of Texas at Austin have measured the mass of the supermassive black hole at the center of Leo I, a small satellite galaxy of our Milky Way. Most supermassive black holes in small galaxies have small masses, and large galaxies have massive black holes. However Leo I has a black hole nearly as massive as our Milky Way’s black hole even though the galaxy itself is 30 times smaller in mass than our galaxy. The astronomers also measured how much dark matter is in Leo I and were again surprised because Leo I has abnormally small amounts of dark matter.
DART Launched – NASA’s Double Asteroid Redirection Test (DART) was launched from California in late November. In September 2022, DART will smash into the asteroid Dimorphos at a speed of 4 miles per second. The idea is to see how much the asteroid’s orbit will change by hitting it with a spacecraft. This effect cannot currently be accurately predicted due to uncertainties about the structure and material inside asteroids. Dimorophos has a diameter about 530 feet and orbits about a somewhat larger asteroid Didymos with a diameter of about 2,560 feet. Neither of these asteroids is any threat to impact Earth, but the exercise will help prepare us if an asteroid is found on an impact course with Earth. Changing an asteroid’s orbit just slightly years in advance of a collision can avoid an impact. A small spacecraft with camera will separate from DART to image the impact. DART will test automatic navigation using imaging designed to hit a specific target and a new Xenon ion engine. The choice of Dimorphos was made because tiny changes in the orbit of a binary asteroid can be accurately measured by Earth-based telescopes. After the collision, the European Space Agency will launch the Hera spacecraft to visit Dimorphos to investigate the damage.
IXPE Launched – The Imaging X-ray Polarimetry Explorer (IXPE) launched from Florida in early December. It is the first X-ray space telescope dedicated to measuring the polarization of X-ray light. Targets will include black holes, supernova remnants, neutron stars, and other high-energy cosmic objects. IXPE has three telescopes with detectors sensitive to polarization. The polarization measurements are expected to give astronomers clues to how the X-rays were generated.
Approach To the Sun – The Parker Solar Probe is planned to make 24 orbits about the Sun, each approaching our star more closely than previously. Parker just completed its tenth close pass to the Sun, coming within 5.3 million miles of its surface, and setting a new record for spacecraft solar proximity. Johannes Kepler told us that because of orbital mechanics, a body at its closest approach to the Sun will be moving at its fastest speed. The Parker Solar Probe was moving at 364,660 miles per hour at its closest approach, a new spacecraft speed record.
LCRD Launched – Laser Communications Relay Demonstration (LCRD) was launched from Florida as part of the STPSat-6 mission. LCRD will demonstrate communicating between satellites and ground using infrared lasers rather than radio, which should increase data rates by ten to 100 times and decrease power required. Planned experiments will measure the effects of weather and atmosphere on laser communication. LCRD will operate from geosynchronous orbit, about 22,000 miles above Earth. It will also demonstrate laser communication with the International Space Station later in its mission.
