Enlarge (credit: ESO/M. Kornmesser )

Quasars initially confused astronomers when they were discovered. First identified as sources of radio-frequency radiation, later observations showed that the objects had optical counterparts that looked like stars. But the spectrum of these ostensible stars showed lots of emissions at wavelengths that didn't seem to correspond to any atoms we knew about.

Eventually, we figured out these were spectral lines of normal atoms but heavily redshifted by immense distances. This means that to appear like stars at these distances, these objects had to be brighter than an entire galaxy. Eventually, we discovered that quasars are the light produced by an actively feeding supermassive black hole at the center of a galaxy.

But finding new examples has remained difficult because, in most images, they continue to look just like stars—you still need to obtain a spectrum and figure out their distance to know you're looking at a quasar. Because of that, there might be some unusual quasars we've ignored because we didn't realize they were quasars. That's the case with an object named J0529−4351, which turned out to be the brightest quasar we've ever observed.

Enlarge (credit: NRAO/AUI/NSF/NASA )

Virtually anything in space could be a potential meal for a supermassive black hole , and that includes entire stars. Even stars much bigger than our Sun can fall victim to the black hole’s extreme gravity and be pulled in toward its gaping maw. It is a terrifying phenomenon, but how often does it really happen?

Tidal disruption events (TDEs)—when the tidal forces of a black hole overwhelm a star’s gravity and tear it apart—are thought to occur once every 10,000 to 100,000 years in any given galaxy. TDEs can be detected by the immense amounts of energy they give off. While observations of them are still pretty rare, an international team of researchers has now discovered a whopping 18 of them that previous searches had missed. Why?

Many TDEs can be found in dusty galaxies. Dust obscures many wavelengths of radiation, from optical to X-rays, but long infrared wavelengths are much less susceptible to scattering and absorption. When the team checked galaxies in the infrared, they found 18 TDEs that had eluded astronomers before.

Enlarge / Like Kepler-10 b, illustrated above, newly discovered exoplanet HD 63433 d is a small, rocky planet in a tight orbit of its star. (credit: NASA/Ames/JPL-Caltech/T. Pyle)

Astronomers have discovered an unusual Earth-sized exoplanet they believe has a hemisphere of molten lava, with its other hemisphere tidally locked in perpetual darkness. Co-authors and study leaders Benjamin Capistrant (University of Florida) and Melinda Soares-Furtado (University of Wisconsin-Madison) presented the details yesterday at a meeting of the American Astronomical Society in New Orleans. An associated paper has just been published in The Astronomical Journal. Another paper published today in the journal Astronomy and Astrophysics by a different group described the discovery of a rare small, cold exoplanet with a massive outer companion 100 times the mass of Jupiter.

As previously reported , thanks to the massive trove of exoplanets discovered by the Kepler mission, we now have a good idea of what kinds of planets are out there, where they orbit, and how common the different types are. What we lack is a good sense of what that implies in terms of the conditions on the planets themselves. Kepler can tell us how big a planet is, but it doesn't know what the planet is made of. And planets in the "habitable zone" around stars could be consistent with anything from a blazing hell to a frozen rock.

The Transiting Exoplanet Survey Satellite (TESS) was launched with the intention of helping us figure out what exoplanets are actually like. TESS is designed to identify planets orbiting bright stars relatively close to Earth, conditions that should allow follow-up observations to figure out their compositions and potentially those of their atmospheres.

Enlarge / Odd radio circles are large enough to contain galaxies in their centers and reach hundreds of thousands of light years across. (credit: Jayanne English / University of Manitoba)

The discovery of so-called "odd radio circles" several years ago had astronomers scrambling to find an explanation for these enormous regions of radio waves so far-reaching that they have galaxies at their centers. Scientists at the University of California, San Diego, think they have found the answer: outflowing galactic winds from exploding stars in so-called "starburst" galaxies. They described their findings in a new paper published in the journal Nature.

“These galaxies are really interesting,” said Alison Coil of the University of California, San Diego. “They occur when two big galaxies collide. The merger pushes all the gas into a very small region, which causes an intense burst of star formation. Massive stars burn out quickly, and when they die, they expel their gas as outflowing winds.”

As reported previously , the discovery arose from the Evolutionary Map of the Universe (EMU) project, which aims to take a census of radio sources in the sky. Several years ago, Ray Norris, an astronomer at Western Sydney University and CSIRO in Australia, predicted the EMU project would make unexpected discoveries. He dubbed them "WTFs." Anna Kapinska , an astronomer at the National Radio Astronomy Observatory (NRAO) was browsing through radio astronomy data collected by CSIRO's Australian Square Kilometer Array Pathfinder (ASKAP) telescope when she noticed several strange shapes that didn't seem to resemble any known type of object. Following Norris' nomenclature, she labeled them as possible WTFs. One of those was a picture of a ghostly circle of radio emission, "hanging out in space like a cosmic smoke ring."

Enlarge / X-ray emissions (purple) superimposed on a visible light image of a galaxy shows the galaxy winds being launched. (credit: X-ray: NASA/CXC/The Ohio State Univ/S. Lopez et al.; H-alpha and Optical: NSF/NOIRLab/AURA/KPNO/CTIO; Infrared: NASA/JPL-Caltech/Spitzer/D. Dale et al; Full Field Optical: ESO/La Silla Observatory. )

One of the ways massive stars, those at least 10-times bigger than the Sun, reach their end is in a supernova—an enormous explosion caused by the star’s core running out of fuel.

One consequence of a supernova is the production of galactic winds, which play a key role in regulating star formation. Although galactic winds have already been observed in several nearby galaxies, a team of scientists has now made the first direct observations of this phenomenon in a large population of galaxies in the distant Universe, at a time when galaxies are in their early stages of formation.

Feedback

According to the study’s lead author, Yucheng Guo, of the Centre de Recherche Astrophysique de Lyon, galactic winds are an important part of the galaxy evolution models.

Enlarge / A compact dwarf galaxy, which may have features that are difficult to explain with standard models of dark matter. (credit: ESA/Hubble & NASA )

It is impossible for a telescope to image and far from being completely understood, yet dark matter is everywhere.

The deepest mysteries about dark matter relate to its nature and behavior. The prevailing idea regarding dark matter is the cold dark matter theory (CDM), which posits that dark matter is made up of low-velocity particles that do not interact with each other. This thinking has been debated—and it is up for debate again. Led by astrophysicist Hai-Bo Yu, a team of researchers from the University of California Riverside have come up with an alternative idea that explains two extremes where cold dark matter doesn't work well.

Galaxies and galaxy clusters are thought to be surrounded by halos of dark matter . At one end of the controversy are galactic dark matter halos that are too dense to be consistent with CDM, and at the other are galactic dark matter halos too diffuse for CDM to make sense of. Yu and his colleagues instead suggest that some dark force (sorry Star Wars fans—not the Force) causes dark matter particles to smash into each other. This is Self-Interacting Dark Matter, or SIDM.

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.