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Some galaxies, like the Milky Way, have maintained regular star formation for billions of years. Others, like large elliptical galaxies, are “red and dead.” Star formation in those galaxies shut off long ago. Astronomers have long suspected the nefarious influence of supermassive black holes, and new research has found the smoking gun.

An international team of astronomers led by Kei Ito at SOKENDAI (the Graduate University for Advanced Studies) in Japan performed a census of galaxies from 9.5 to 12.5 billion years away. They took their data from the Cosmic Evolution Survey (COSMOS) catalog, which combines data by many world-class telescopes, including the Atacama Large Millimeter/submillimeter Array and the Subaru telescope. COSMOS includes radio, infrared, visible, and x-ray data into a single comprehensive catalog of over a hundred thousand galaxies in the universe. The research team reported their results in a recent paper appearing in The Astrophysical Journal.

The team started by using visible and infrared wavelengths to sort their galaxies into two groups. One group had ongoing star formation, while the other group ended star formation. They team then used radio and x-ray observations to determine if the galaxies hosted an active supermassive black hole.

The radio and x-ray emission from each individual galaxy was far too weak to study in isolation. So instead, the astronomers combined the observations from many galaxies, building up a sense of how the “average” galaxy in each group behaved. They found that in the dead galaxies, the amount of radio and x-ray emission was too much to be accounted for by stars alone.

A study of galaxies to determine if supermassive black holes really do shut off star formation.
The COSMOS survey region surrounded by images of galaxies used in this study. In these galaxies star formation ceased around 10 billion years ago. (3-color false-color composite images combining data from the Subaru Telescope and VISTA) (Credit: NAOJ)

To the astronomers, this suggested that supermassive black holes were active in the dead galaxies. When the black holes become too active, they spew tremendous amounts of energy into their host galaxies. This makes the gas in the galaxies too hot, slowing down star formation. In some cases, the black holes can blow so much material out of the galaxies altogether that star formation completely stops.

This research suggests that something abrupt happened to galaxies in the early universe. Galaxies back then suddenly found their central black holes blasting away, killing star formation in entire populations of galaxies, well before the present epoch. Future research will be needed to understand exactly what happened.

The post Do Supermassive Black Holes Prematurely end Star Formation in Some Galaxies? appeared first on Universe Today.

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Will We Know if TRAPPIST-1e has Life?

The search for extrasolar planets is currently undergoing a seismic shift. With the deployment of the Kepler Space Telescope and the Transiting Exoplanet Survey Satellite (TESS), scientists discovered thousands of exoplanets, most of which were detected and confirmed using indirect methods. But in more recent years, and with the launch of the James Webb Space Telescope (JWST), the field has been transitioning toward one of characterization. In this process, scientists rely on emission spectra from exoplanet atmospheres to search for the chemical signatures we associate with life (biosignatures).

However, there’s some controversy regarding the kinds of signatures scientists should look for. Essentially, astrobiology uses life on Earth as a template when searching for indications of extraterrestrial life, much like how exoplanet hunters use Earth as a standard for measuring “habitability.” But as many scientists have pointed out, life on Earth and its natural environment have evolved considerably over time. In a recent paper, an international team demonstrated how astrobiologists could look for life on TRAPPIST-1e based on what existed on Earth billions of years ago.

The team consisted of astronomers and astrobiologists from the Global Systems Institute, and the Departments of Physics and Astronomy, Mathematics and Statistics, and Natural Sciences at the University of Exeter. They were joined by researchers from the School of Earth and Ocean Sciences at the University of Victoria and the Natural History Museum in London. The paper that describes their findings, “Biosignatures from pre-oxygen photosynthesizing life on TRAPPIST-1e,” will be published in the Monthly Notices of the Royal Astronomical Society (MNRAS).

The TRAPPIST-1 system has been the focal point of attention ever since astronomers confirmed the presence of three exoplanets in 2016, which grew to seven by the following year. As one of many systems with a low-mass, cooler M-type (red dwarf) parent star, there are unresolved questions about whether any of its planets could be habitable. Much of this concerns the variable and unstable nature of red dwarfs, which are prone to flare activity and may not produce enough of the necessary photons to power photosynthesis.

With so many rocky planets found orbiting red dwarf suns, including the nearest exoplanet to our Solar System (Proxima b), many astronomers feel these systems would be the ideal place to look for extraterrestrial life. At the same time, they’ve also emphasized that these planets would need to have thick atmospheres, intrinsic magnetic fields, sufficient heat transfer mechanisms, or all of the above. Determining if exoplanets have these prerequisites for life is something that the JWST and other next-generation telescopes – like the ESO’s proposed Extremely Large Telescope (ELT) – are expected to enable.

But even with these and other next-generation instruments, there is still the question of what biosignatures we should look for. As noted, our planet, its atmosphere, and all life as we know it have evolved considerably over the past four billion years. During the Archean Eon (ca. 4 to 2.5 billion years ago), Earth’s atmosphere was predominantly composed of carbon dioxide, methane, and volcanic gases, and little more than anaerobic microorganisms existed. Only within the last 1.62 billion years did the first multi-celled life appear and evolve to its present complexity.

Moreover, the number of evolutionary steps (and their potential difficulty) required to get to higher levels of complexity means that many planets may never develop complex life. This is consistent with the Great Filter Hypothesis, which states that while life may be common in the Universe, advanced life may not. As a result, simple microbial biospheres similar to those that existed during the Archean could be the most common. The key, then, is to conduct searches that would isolate biosignatures consistent with primitive life and the conditions that were common to Earth billions of years ago.

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NASA Restores Communications with Voyager 1

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The venerable Voyager 1 spacecraft is finally phoning home again. This is much to the relief of mission engineers, scientists, and Voyager fans around the world.

On November 14, 2023, the aging spacecraft began sending what amounted to a string of gibberish back to Earth. It appeared to be getting commands from Earth and seemed to be operating okay. It just wasn’t returning any useful science and engineering data. The team engineers began diagnostic testing to figure out if the spacecraft’s onboard computer was giving up the ghost. They also wanted to know if there was some other issue going on.

It wasn’t completely surprising that Voyager 1 would have issues, after all. And, this isn’t the first time Voyager 1 has sent back garbly data. It’s been traversing space since its launch in 1977. Currently, the spacecraft is rushing away from the Solar System toward interstellar space. The spacecraft systems will eventually fail due to age and lack of power. But, people have always held out hope for them to last as long as possible. That’s because Voyager 1 is probing unexplored regions of space.

What Happened to Voyager 1?

The diagnostic testing led the engineering team at NASA’s Jet Propulsion Laboratory to look at old engineering documents and manuals for the onboard computers. Eventually, they found that the flight data subsystem (FDS) was having an issue. In the spacecraft’s data handling pipeline, this system takes information from the instruments and packages it into a data stream for the long trip back to Earth.

It turns out that the FDS has a bit of a memory problem. The engineers found this out by poking at the computer—literally sending a “poke” command to Voyager 1. That prompted the FDS to disgorge a readout of its memory—including the software code and other code values. The readout showed that about 3 percent of the FDS memory is corrupted due to a single chip failing. That’s just enough to keep the computer from doing its normal work of packaging science and engineering data. Unfortunately, engineers can’t replace the chip. No repair is possible, so the technical team devised a workaround.

Fixing the Faulty Code and Chip

So, how did engineers reach across 24 billion kilometers of space to restore communication with Voyager 1? They focused on a specific part of the computer. The loss of the code on that failed chip made it impossible for the computer to do its job. So, they figured out a way to divide the code into sections and store them in various locations around the FDS. Then they had to make the sections work together to do their original job.

They started out by taking the code that packages engineering data and moving it to a safe spot in FDS. Then they sent some commands to the spacecraft for the FDS to do some tasks. That worked because, on April 20th, they heard back from the spacecraft with clear, intelligible data. Now, they just need to do the same thing with other bits of code so that the spacecraft can send back both engineering and science data.

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The Voyager 1 flight team members celebrate in a conference room at NASA’s Jet Propulsion Laboratory on April 20 after receiving confirmation that their repair to the spacecraft’s FDS worked. Credit: NASA/JPL-Caltech

For now, at least, the science and engineering teams can check the spacecraft’s health and its systems. Once they relocate the other bits of code and test them after being moved, they should be able to start receiving science data again. This could take several weeks to accomplish. They’re communicating with a spacecraft that’s 22.5 light-hours away, so having a lengthy diagnostic conversation with Voyager is going to take some time. This isn’t the only problem engineers have had to contend with recently with Voyager 1. In October 2023, they worked to overcome a fuel flow problem affecting its thrusters.

Voyager 1 Into History

Voyager 1 was launched on a planetary flyby trajectory on September 5, 1977. It passed by Jupiter in March 1979 and Saturn in November 1980. The mission then morphed into an extended period of exploration and exited the heliopause in 2012. On its way out of the Solar System, the spacecraft also “looked back” at Earth. Now, it’s exploring the interstellar medium but has not yet traversed the Oort Cloud, the outermost portion of the Solar System.

This updated version of the iconic
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There Was a Doomed Comet Near the Sun During the Eclipse

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A surprise appearance of a new comet made the April 8th total solar eclipse all the more memorable.

Any dedicated ‘umbraphile’ will tell you: no two eclipses are exactly the same. Weather, solar activity, and the just plain expeditionary nature of reaching and standing in the shadow of the Moon for those brief moments during totality assures a unique experience, every time out. The same can be said for catching a brief glimpse of what’s going on near the Sun, from prominences and the pearly white corona to the configuration of bright planets… and just maybe, a new comet.

The Discovery

While many planned to try and spy periodic Comet 12P Pons-Brooks during totality, astronomer Karl Battams at the U.S. Naval Observatory alerted us to another possibility. A new sungrazing comet, spotted just hours prior. The Kreutz family comet was seen by Worachate Boonplod in the field of view of the joint NASA/ESA Solar Heliospheric Observatory’s (SOHO) LASCO C3 and C2 imagers. These are equipped with Sun-covering coronagraphs that allow it to see the near solar environment. The mission was launched over a quarter of a century ago in 1995. SOHO was deployed to the sunward L1 Earth-Sun Lagrange point nearly a million miles distant. SOHO has since proven itself to be a crucial workhorse in solar heliophysics.

Doomed SOHO-5008 (lower left). Credit: NASA/ESA/SOHO

The comet soon received the formal designation of SOHO-5008. That’s right: SOHO has led to the discovery of over 5,000 comets in its career. Most of these discoveries were thanks to the efforts of dedicated online sleuths, scouring recent LASCO images.

At the time, the doom’d comet was a faint object, located only a few degrees from the Sun. The icy interloper was a tough target to nab during the fleeting minutes of totality, but at least two dedicated astrophotographers managed to catch it. Lin Zixuan saw it imaging from northern New Hampshire. Petr Horálek from the Institute of Physics in Opava Czechia (Czech Republic) was imaging from Mexico as he caught the object.

Like so many other sungrazers, the comet met its demise shortly after discovery (less than 12 hours, in fact), like a sundiving spaceship at a Disaster Area concert right out of Douglas Adam’s Hitchhiker’s Guide to the Galaxy.

Brief History of Sungrazers

This sort of SOHO versus comet, versus eclipse discovery has only occurred twice: once in 2008 and again in 2020). SOHO wasn’t designed per se to find comets, but its prolific nature as a comet hunter has become an essential part of the legacy of the mission. SOHO has defined whole new families of Kreutz, Marsden and Kracht sungrazing comets. And to think, prior to the mission, only sixteen sungrazing comets were even known of.

One similar case was the Great Comet of 1948, which was also discovered by stunned observers during a total solar eclipse. Another was C/1965 Ikeya-Seki, which went on to become one of the truly great comets of the 20th century. More recently, C/2011 W3 Lovejoy surprised everyone by surviving its perihelion passage 140,000 kilometers from the surface of the Sun. Just one year later, however, 2012 S1 ISON didn’t.

It was a thrilling celestial spectacle, with an added treat.

The post There Was a Doomed Comet Near the Sun During the Eclipse appeared first on Universe Today.

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