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

Dense Exoplanet – Observations by astronomers at the Pennsylvania State University found an unusually dense exoplanet orbiting a star in the Hyades open star cluster. Known as K2-25b, it is slightly smaller than Neptune but about 1.5 times as massive. This is reminiscent of a planet announced about a month ago named TOI 849 b, also of unusually high density. In both cases, astronomers have yet to figure out how either a gas giant can form without much of its gas, or how it can later lose much of its gas. K2-25b orbits a red dwarf star every 3.5 Earth days. The star and planet are young, only about 600 million years, and are located about 150 light-years away.

Amateurs Find Exoplanet – A team of amateur astronomers from the Habitable Exoplanet Hunting Project announced they discovered what appears to be a Saturn-sized planet orbiting the red dwarf star Gliese 3470, about 100 light-years away in the constellation Cancer. Its year is 66 Earth days and that puts it in the star’s habitable zone, the area where temperatures may allow liquid water to exist on the planet’s surface. If confirmed, this will be the first exoplanet found by an entirely amateur astronomer team. They found it by observing the changing brightness of the star as the planet transits in front of it. They observed other probable transits as well, but no pattern to them has yet been found, but this likely means there are more planets in this system to be found. There is already one previously known planet, which is Neptune-sized, orbiting much closer to that star.

Exoplanet Found By Radio – An exoplanet, dubbed TVLM 513b, was discovered using radio observations for the first time. Those observations were led by astronomers at the National Autonomous University of Mexico using the VLBA, an array of radiotelescopes spread across the North American continent. The huge size of the telescope allows for extremely precise resolution, which enabled the astronomers to track the host star’s movement as the gravitational tug of the planet causes the star to trace a tiny ellipse in the sky. This method of finding planets is known as the astrometric method, and has rarely been used successfully due to the extreme precision required. Previously it was used with visible light, not radio. The planet is about the mass of Saturn, but its orbit is about the size of Mercury’s. It orbits a tiny red dwarf star about 35 light-years away, taking 221 Earth days per orbit. Giant planets at tiny stars are somewhat rare.

Unusual Magnetar – An international coalition of researchers led by astronomers at the National Institute for Astrophysics in Milan found a star emitting a unique variety of radiation, including X-rays and short, powerful radio bursts. It is a known magnetar, a neutron star with an extremely powerful magnetic field. The radio bursts observed resemble the Fast Radio Bursts (FRBs), mysterious radio pulses that have been observed throughout the sky but whose sources are still unknown. All FRBs seen so far originated from outside the galaxy, while this magnetar is inside our Milky Way. Further observation of this object may indicate that the as yet unknown source of FRBs is actually magnetars. However, no X-rays have ever been observed from the same source as an FRB, so the situation may not be that simple.

Misclassified Black Holes – Black holes found in the X-ray version of the Deep Field South image were studied by a team from Johns Hopkins University using multiple telescopes and multiple types of light. This effort found that many black holes have been misclassified. In particular many black holes thought to be showing little activity with minimal material falling into them, were actually quite active, but heavily obscured by dust and gas about them. The black holes chosen for study were all more than five billion light-years away. There were already 67 known active but obscured black holes, but the new study found 28 more that had been misclassified. This implies that several fields of study related to black holes need to adjust their numbers, such as growth rates of black holes in the early history of the Universe, amounts of gas and dust around such black holes and the contribution of black hole X-rays to the cosmic X-ray background.

Unusual Pulsar Found – Pulsars have been placed in three classes according to what powers their pulses. They’re either rotation-powered and usually pulse in radio; accretion-powered and pulse in X-rays emitted by spots where material pulled from their companion star hits the pulsar; or magnetically-powered where magnetars pulse in X-rays and gamma rays. Observations, led by astronomers at the Scuola Superiore IUSS in Italy, of a recently discovered young pulsar known as Swift J18180-1607 don’t fit these classes. It is a magnetar, yet also emits in radio. Its brightness between pulses is unusually low. It may differ from previous pulsars because it rotates faster than any other known magnetar, at 1.36 seconds per rotation.

Neutron Star Found – In 1987, a star exploded in the nearby galaxy, the Large Magellanic Cloud. Ever since that supernova, astronomers have been looking for a neutron star expected to be left behind. The detection of neutrinos from the explosion back in 1987 indicated that this supernova should have produced a neutron star, not a black hole. Two teams of astronomers from the Universidad Nacional Autónoma de México and Cardiff University using the ALMA radiotelescope array announced that they found a hot object that fits what is expected for such a neutron star, likely with a cloud of dust blocking a clear view. Astronomers hope that the dust will dissipate in future years, eventually allowing a direct view of the neutron star. It is likely not a pulsar, a neutron star with a rotating beam. This would be the youngest known neutron star, as the last supernova close enough to produce a neutron star that could be seen occurred about 330 years ago.

Globular Cluster Torn Apart – A team of astronomers led by researchers from the University of Sydney identified a stream of stars near our Milky Way galaxy in the constellation Phoenix and determined that it was once a globular cluster before a close pass by our galaxy tore it apart gravitationally about two billion years ago. The concentration of elements heavier than hydrogen and helium in the stream is lower than any other globular cluster that orbits our galaxy. It will take adjustment of globular cluster formation theory to explain this low concentration.

Aluminum-26 – Particles rich in calcium and aluminum found in many meteorites originally formed with substantial amounts of aluminum-26, a radioactive isotope of aluminum. For many years, scientists believed it indicated a supernova or the stellar wind of a massive star had blown aluminum-26 into the nebula that ultimately formed the Sun. No other source of substantial amounts of aluminum-26 was known. Now, new research by a team at the University of Cologne shows that cosmic rays striking the dust in a protostellar disk also creates aluminum-26, and that still-forming stars create the cosmic rays needed to do so. Astronomers still believe a supernova happened nearby just before the Sun formed as there is other evidence for a supernova at that time, such as iron-60 found in meteorites, but the Sun itself likely added to the aluminum-26 from the supernova. However, this may change the time scales calculated for newly formed planets and moons to cool, as aluminum-26 radioactively decaying was a substantial source of heat when those bodies formed.

Ocean at Ceres – Astronomers from the Istituto Nazionale di Astrofisica in Rome, working with archived data from the Dawn space probe have concluded that a liquid ocean, or at least fragments of one, exists beneath the icy surface of Ceres. That asteroid has more water than any other body in the inner Solar System except Earth. Before Dawn’s observations, scientists thought that all that water there had frozen eons ago. This new conclusion was based on surface features that appeared to be formed by leaking water and on variations in Ceres’s gravitational field. The astronomers believe that the ocean must be very salty and that hydrate chemical compounds must have formed that conduct heat poorly, preventing the asteroid from freezing completely through. The best estimates are that liquid water stretches for hundreds of miles parallel to the surface at roughly 25 miles in depth.

Waves on Titan – It has long been known that sunlight glares can be seen in images taken of the methane and ethane lakes found on Saturn’s moon Titan. A new study by researchers at the University of Idaho looked for glitters, glares reflected off lake surfaces that are not smooth but wavy, diminishing the brilliance of the glare. The study used archived observations from the Cassini Saturn orbiter mission. It has been previously calculated that waves in Titan’s lakes and seas likely do not exceed eight inches in height. The small size is due to Titan’s huge distance from the Sun, which produces rather mild sunlight-induced winds. The study found several glitter instances, especially near two straits in Kraken Mare, the largest Titanic sea. The study team suggested the glitters were caused by some combination of tides, winds, and flows over shallows.

Cold and Wet Mars – Researchers at the University of British Columbia made a computer analysis of 66 networks of valleys on Mars, composed of 10,000 individual valleys, comparing their patterns and shapes to valleys on Earth of known origin. Only 14 of the networks matched earthly valley networks formed by flowing rivers, while 31 of them matched networks formed by meltwater flowing beneath glaciers. Three of the networks matched sapping valleys, a process where seeping groundwater erodes the ground. The researchers came to the conclusion that 3.8 billion years ago, when many of the valleys formed, much of Mars was experiencing rather cold times, such that more erosion occurred under ice sheets than by flowing rivers. It might be more accurate to describe ancient Mars as cold and wet, not warm and wet. This may increase the chances that simple life forms evolved on Mars during that time, since massive glaciers would protect the watery regions beneath from hazardous radiation.

Warm and Wet Mars – Another new study, this one by scientists at the University of Texas at Austin, showed that significant amounts of water flowed on ancient Mars between about 3.5 and four billion years ago, beyond the glacier action implied by the previous item. This new study examined 96 Martian basins that in ancient times were filled with water and became lakes. Some of them had filled to overflowing (termed open lakes) and others did not overflow (called closed lakes). The volume of open lakes was used to determine the minimum amount of water that flowed into such lakes, and the volume of closed lakes was used as a maximum. Such flows would make up a single episode, water flowing without breaks significant enough to allow evaporation to substantially diminish the volume of the lake. The flowing water could be from either from rainfall or snowmelt, or a combination. The study calculated how much water would have to precipitate over the watershed feeding the lake inlet. The result was that 13 to 520 feet of water would have had to precipitate in an episode to create the lakes studied. If the precipitation fell in multiple episodes, then the total water would be even greater in order to replace evaporation.

Arecibo Damaged – A cable helping to support the receiving platform above the dish of the Arecibo radiotelescope broke and damaged a portion of the dish. The telescope will be out of service for some time while repairs are made. Arecibo is the second largest radio dish in the world and has long been active in observing objects throughout the Universe and in radaring and observing Solar System objects. The cause of the cable break is under investigation.