Enlarge / Scientists have found a large black hole that “hiccups,” giving off plumes of gas. (credit: Jose-Luis Olivares, MIT)

In December 2020, astronomers spotted an unusual burst of light in a galaxy roughly 848 million light-years away—a region with a supermassive black hole at the center that had been largely quiet until then. The energy of the burst mysteriously dipped about every 8.5 days before the black hole settled back down, akin to having a case of celestial hiccups.

Now scientists think they've figured out the reason for this unusual behavior. The supermassive black hole is orbited by a smaller black hole that periodically punches through the larger object's accretion disk during its travels, releasing a plume of gas. This suggests that black hole accretion disks might not be as uniform as astronomers thought, according to a new paper published in the journal Science Advances.

Co-author Dheeraj "DJ" Pasham of MIT's Kavli Institute for Astrophysics and Space research noticed the community alert that went out after the All Sky Automated Survey for SuperNovae (ASAS-SN) detected the flare, dubbed ASASSN-20qc. He was intrigued and still had some allotted time on the X-ray telescope, called NICER (the Neutron star Interior Composition Explorer) on board the International Space Station. He directed the telescope to the galaxy of interest and gathered about four months of data, after which the flare faded.

Enlarge / A new image from the Event Horizon Telescope has revealed powerful magnetic fields spiraling from the edge of a supermassive black hole at the center of the Milky Way, Sagittarius A*. (credit: EHT Collaboration)

Physicists have been confident since the1980s that there is a supermassive black hole at the center of the Milky Way galaxy, similar to those thought to be at the center of most spiral and elliptical galaxies. It's since been dubbed Sagittarius A* (pronounced A-star), or SgrA* for short. The Event Horizon Telescope (EHT) captured the first image of SgrA* two years ago. Now the collaboration has revealed a new polarized image (above) showcasing the black hole's swirling magnetic fields. The technical details appear in two new papers published in The Astrophysical Journal Letters. The new image is strikingly similar to another EHT image of a larger supermassive black hole, M87*, so this might be something that all such black holes share.

The only way to "see" a black hole is to image the shadow created by light as it bends in response to the object's powerful gravitational field. As Ars Science Editor John Timmer reported in 2019, the EHT isn't a telescope in the traditional sense. Instead, it's a collection of telescopes scattered around the globe. The EHT is created by interferometry, which uses light in the microwave regime of the electromagnetic spectrum captured at different locations. These recorded images are combined and processed to build an image with a resolution similar to that of a telescope the size of the most distant locations. Interferometry has been used at facilities like ALMA (the Atacama Large Millimeter/submillimeter Array) in northern Chile, where telescopes can be spread across 16 km of desert.

In theory, there's no upper limit on the size of the array, but to determine which photons originated simultaneously at the source, you need very precise location and timing information on each of the sites. And you still have to gather sufficient photons to see anything at all. So atomic clocks were installed at many of the locations, and exact GPS measurements were built up over time. For the EHT, the large collecting area of ALMA—combined with choosing a wavelength in which supermassive black holes are very bright—ensured sufficient photons.

Enlarge (credit: NASA/JPL-Caltech )

You win some, you lose some. Earlier this week , observations made by the Webb Space Telescope provided new data that supports what we thought we understood about planet formation. On Thursday, word came that astronomers spotted a large planet orbiting close to a tiny star—a star that's too small to have had enough material around it to form a planet that large.

This doesn't mean that the planet is "impossible." But it does mean that we may not fully understand some aspects of planet formation.

A big mismatch

LHS 3154 is, by any reasonable measure, a small, dim star. Imaging by the team behind the new work indicates that the red dwarf has just 11 percent of the Sun's mass. Temperature estimates place it at about 2,850 K, far lower than the Sun's 5,800 K temperature and barely warm enough to keep it out of ultracool dwarf category. (Yes, ultracool dwarfs are enough of a thing to merit their own Wikipedia entry .)

Enlarge / Image of a planet-forming disk, with gaps in between higher-density areas. (credit: ALMA(ESO/NAOJ/NRAO); C. Brogan, B. Saxton )

Where do planets come from? The entire process can get complicated. Planetary embryos sometimes run into obstacles to growth that leave them as asteroids or naked planetary cores. But at least one question about planetary formation has finally been answered—how they get their water.

For decades, planetary formation theories kept suggesting that planets receive water from ice-covered fragments of rock that form in the frigid outer reaches of protoplanetary disks, where light and heat from the emerging system’s star lacks the intensity to melt the ice. As friction from the gas and dust of the disk moves these pebbles inward toward the star, they bring water and other ices to planets after crossing the snow line, where things warm up enough that the ice sublimates and releases huge amounts of water vapor. This was all hypothesized until now.

NASA’s James Webb Telescope has now observed groundbreaking evidence of these ideas as it imaged four young protoplanetary disks.The telescope used its Medium-Resolution Spectrometer (MRS) of Webb’s Mid-Infrared Instrument (MIRI) to gather this data, because it is especially sensitive to water vapor. Webb found that in two of these disks, massive amounts of cold water vapor appeared past the snow line, confirming that ice sublimating from frozen pebbles can indeed deliver water to planets like ours.

Enlarge (credit: NOIRLab/NSF/AURA/M. Garlick/M. Zamani )

What is hundreds of billions of times more powerful than the Sun, flashes on repeat with intense bursts of light, and verges on defying the laws of physics? No, it’s not your neighbors’ holiday lights glitching again. It’s an LFBOT in the depths of space.

LFBOTs (Luminous Fast Blue Optical Transients) are already quite bizarre. They erupt with blue light, radio, X-ray, and optical emissions, making them some of the brightest explosions ever seen in space, as luminous as supernovae. It is no exaggeration that they give off more energy than hundreds of billions of stars like our own. They also tend to live fast, blazing for only minutes before they burn themselves out and fade into darkness.

LFBOTs are quite rare, and in many cases their sources are unidentified. But we’ve never seen anything with the intensity of an LFBOT named AT2022tsd—aka the “Tasmanian Devil.” Its strange behavior was caught by 15 telescopes and observatories, including the W.M. Keck Observatory and NASA’s Chandra Space Telescope. Like other phenomena of its kind, it initially emitted incredible amounts of energy and then dimmed. Unlike any other LFBOT observed before, however, this one seemed to come back from the dead. It flared again—and again and again.

Astronomers involved with the Telescope Array experiment in Utah's West Desert have detected an ultra-high-energy cosmic ray (UHECR) with a whpping energy level of 244 EeV, according to a new paper published in the journal Science. It's the most energetic cosmic ray detected since 1991, when astronomers detected the so-called "Oh-My-God' particle , with energies of an even more impressive 320 EeV. Astronomers have dubbed this latest event the "Amaterasu" particle, after the Shinto sun goddess said to have created Japan. One might even call it the "Oh-My-Goddess" particle.

Cosmic rays are highly energetic subatomic particles traveling through space near the speed of light. Technically, a cosmic ray is just an atomic nucleus made up of a proton or a cluster of protons and neutrons. Most originate from the Sun, but others come from objects outside our solar system. When these rays strike the Earth’s atmosphere, they break apart into showers of other particles (both positively and negatively charged).

They were first discovered in 1912 by Austrian physicist Victor Hess via a series of ascents in a hydrogen balloon to take measurements of radiation in the atmosphere with an electroscope. He found that the rate of ionization was a good three times the rate at sea level, thereby disproving a competing theory that this radiation came from the rocks of  Earth. If you've ever seen a cloud chamber in a science museum, cosmic ray tracks look like wispy little white lines, similar to tiny jet contrails.

Science 101 tells us that the twinkling appearance of stars from our vantage point on Earth is due to atmospheric effects: winds and varying temperatures and densities in the air bend and distort the light. But stars have another sort of "twinkle" produced by how gases ripple in waves across their surface, an effect that could provide astronomers with a handy means of exploring the interior of massive stars to learn more about how they form and evolve. But the effect is much too small to be readily detected by telescopes.

So scientists have now developed the first 3D simulations of that innate twinkle, according to a recent paper published in the journal Nature Astronomy. As a bonus, the researchers converted the data from those rippling waves of gas into an audible sound, so now we can all take a moment to listen to "Twinkle, Twinkle, Little Star" (see video above) and Gustav Holst's "Jupiter" (see video below) in the "language" of the stars.

“Motions in the cores of stars launch waves like those on the ocean,” said co-author Evan Anders of Northwestern University. “When the waves arrive at the star’s surface, they make it twinkle in a way that astronomers may be able to observe. For the first time, we have developed computer models which allow us to determine how much a star should twinkle as a result of these waves. This work allows future space telescopes to probe the central regions where stars forge the elements we depend upon to live and breathe.”

Enlarge / Artist's conception of the atmosphere being blasted off an exoplanet. (credit: NASA, ESA, and Joseph Olmsted (STScI) )

Some planets cannot hold on to their atmospheres. It's thought that most of whatever atmosphere Mars may have had was annihilated by the solar wind billions of years ago, even as Earth and Venus held on to theirs. But there are planets that orbit so close to their star that atmospheric loss is inevitable. With at least one of them, we’ve learned that it is also unpredictable.

Exoplanet Au Mic b is that planet. It orbits the young, hot, and temperamental red dwarf star Au Microscopii (Au Mic), which is only 23 million years old—nothing compared to our 4-billion-year-old sun. NASA’s Hubble Space Telescope caught this scorched world losing a portion of its atmosphere.

When a team of scientists from the NASA Goddard Space Flight Center, Dartmouth College, the University of California at Santa Cruz, and other institutions analyzed the Hubble observations, they were confused by the planet’s erratic behavior. There would be evidence of atmospheric loss in some of the data, then suddenly none at all. It was unpredictable.

Enlarge / An artist's conception of an ice-encrusted rogue planet. (credit: NASA’s Goddard Space Flight Center )

Planets that go rogue orbit no star. They wander the vacuum of space alone, having been kicked out of their star systems by gravitational interactions with other planets and stars. Nobody really knows how many rogue planets could be out there, but that may change in a few years.

Researchers from NASA’s Goddard Space Flight Center and Osaka University in Japan have used the phenomenon of gravitational microlensing to estimate the number of rogue planets that could be revealed in the heart of the Milky Way. They analyzed data from the Microlensing Observations in Astrophysics (MOA) survey that searched for gravitational microlensing events from 2006 to 2014 to figure out how many more of these events we could expect to find with NASA’s upcoming Nancy Grace Roman Space Telescope.

There are currently only 70 known rogue planets, but there could be hundreds more out there. The researchers now suggest that Roman could discover at least 400 Earth-mass rogues meandering through our galaxy.