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Showing posts from January, 2024

Webb Directly Images Two Planets Orbiting White Dwarfs

In several billion years, our Sun will become a white dwarf. What will happen to Jupiter and Saturn when the Sun transitions to become a stellar remnant? Life could go on, though the giant planets will likely drift further away from the Sun. Stars end their lives in different ways. Some meet their end as supernovae, cataclysmic explosions that destroy any orbiting planets and even sterilize planets light-years away. But only massive stars explode like that. Our Sun is not massive enough to explode as a supernova. Instead, it’ll spend time as a red giant. The red giant phase occurs when a star runs out of hydrogen to feed fusion. It’s a complicated process that astronomers are still working hard to understand. But red giants shed layers of material into space that light up as planetary nebulae. Eventually, the red giant is no more, and only a tiny, yet extraordinarily dense, white dwarf resides in the middle of all the expelled material. Researchers think that some white dwarfs have

The Aftermath of a Recent Galactic Merger

NGC 4753 is a prime example of what happens after a galactic merger. It looks like a twisted mess, with dust lanes looping around the massive galactic nucleus. Astronomers long wondered what happened to this galaxy, and with a sharp new image created by the Gemini South telescope, they can finally explain its tortured past. Officially, NGC 4753 is classified as a “peculiar” galaxy due to its odd appearance. But, like other survivors of galactic mergers and acquisitions, it has probably had several “shapes” throughout its history. Most galaxies are classified as spirals, ellipticals, lenticulars, and irregulars. For this one, astronomers suspect it was formerly a lenticular with a substantial disk and not much in the way of spiral arms. Then, more than a billion years ago, it encountered a neighboring dwarf galaxy and they tangled together. A team led by astronomer Tom Steiman-Cameron at Indian University studied this galaxy in great detail to understand how it got the way it is today

Feast Your Eyes on 19 Face-On Spiral Galaxies Seen by Webb

If you’re fascinated by Nature, these images of spiral galaxies won’t help you escape your fascination. These images show incredible detail in 19 spirals, imaged face-on by the JWST. The galactic arms with their multitudes of stars are lit up in infrared light, as are the dense galactic cores, where supermassive black holes reside. The JWST captured these images as part of the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) programme. PHANGS is a long-running program aimed at understanding how gas and star formation interact with galactic structure and evolution. One of Webb’s four primary science goals is to study how galaxies form and evolve, and the PHANGS program feeds that effort. The VLT, ALMA, the Hubble, and now the JWST have all contributed to it. But Webb’s images are the juiciest. “Webb’s new images are extraordinary. They’re mind-blowing even for researchers who have studied these same galaxies for decades.” Janice Lee, Project Scientists, Space Tele

A Magnetohydrodynamic Drive Could Lead to Fuel Stations on Mars

Within the next fifteen years, NASA, China, and SpaceX plan to send the first crewed missions to Mars. In all three cases, these missions are meant to culminate in the creation of surface habitats that will allow for many returns and – quite possibly – permanent human settlements. This presents numerous challenges, one of the greatest of which is the need for plenty of breathable air and propellant. Both can be manufactured through electrolysis, where electromagnetic fields are applied to water (H 2 O) to create oxygen gas (O 2 ) and liquid hydrogen (LH 2 ). While Mars has ample deposits of water ice on its surface that make this feasible, existing technological solutions fall short of the reliability and efficiency levels required for space exploration. Fortunately, a team of researchers from Georgia Tech has proposed a “ Magnetohydrodynamic Drive for Hydrogen and Oxygen Production in Mars Transfer ” that combines multiple functionalities into a system with no moving parts. This syst

Atmosphere Pressure Changes Could Explain Mars Methane

One ongoing mystery on Mars is the sporadic detection of atmospheric methane. Since 1999 detections have been made by Earth-based observatories, orbital missions, and on the surface by the Curiosity Rover. However, other missions and observatories have not detected methane at all, and even when detected, the abundances appear to fluctuate seasonally or even daily. So, where does this intermittent methane come from? A group of scientists have proposed an interesting theory: the methane is being sucked out of the ground by changes in pressure in the Martian atmosphere. The researchers simulated how methane moves underground on Mars through networks of underground fractures and found that seasonal changes can force the methane onto the surface for a short time. In their paper, published in the Journal of Geophysical Research: Planets, the scientists say their simulations predict short-lived methane pulses prior to sunrise for Mars’ upcoming northern summer period, which is a candidate

It's a Fine Line Between a Black Hole Energy Factory and a Black Hole Bomb

Black holes are powerful gravitational engines. So you might imagine that there must be a way to extract energy from them given the chance, and you’d be right. Certainly, we could tap into all the heat and kinetic energy of a black hole’s accretion disk and jets, but even if all you had was a black hole in empty space, you could still extract energy from a trick known as the Penrose process. First proposed by Roger Penrose in 1971, it is a way to extract rotational energy from a black hole. It uses an effect known as frame dragging, where a rotating body twists nearby space in such a way that an object falling toward the body is dragged slightly along the path of rotation. We’ve observed the effect near Earth, though it is tiny. Near a rotating black hole, the effect can be huge. So strong that within a region known as the ergosphere objects can be dragged around the black hole at speeds greater than light in free space. Trajectories of bodies in a Penrose process. Credit: Aleksa

NASA Gives us an Update on its Long-term Plans for the Moon and Mars

Going to Mars is a major step in space exploration. It’s not a quick jaunt nor will it be easy to accomplish. The trip is already in the planning stages, and there’s a good chance it’ll happen in the next decade or so. That’s why NASA and other agencies have detailed mission scenarios in place, starting with trips to the Moon. Recently, NASA updated its “Moon to Mars Architecture” documents, including a closer look at some key decisions about Mars exploration. Those decisions cover a wide gamut of challenges to living and working on the Red Planet. NASA planners narrowed them down to these key areas: science priorities, number of crew members on the first trip, how many on each follow-up trip, number of crew members per Mars location, Mars surface power generation technologies, what kinds of missions will be sent (the “target state”), and establishing what they call a “loss of crew risk” posture. That last one involves making the right decisions about missions based on risk to the cr

There’s Less Dark Matter at the Core of the Milky Way

Science really does keep you on your toes. First there was matter and then there were galaxies. Then those galaxies had more stuff in the middle so stars further out were expected to move slowly, then there was dark matter as they actually seemed to move faster but now they seem to be moving slower in our Galaxy so perhaps there is less dark matter than we thought after all!  Let’s start with dark matter.  It is a strange and mysterious form of matter that doesn’t really seem to behave in any way like normal matter. It doesn’t emit light, absorb or reflect it so is to all intents invisible, hence its name. It’s thought that about 27% of the Universe is made up of dark matter but the only way we can detect it is its gravitational effect on passing light and other matter. Despite mounting evidence for its existence, we have still yet to actually detect particles that make up dark matter, whatever they are.  Physicists at MIT (the Massachusetts Institute of Technology) have measured th

Plants Growing in Space are at Risk from Bacterial Infections

I have spent the last few years thinking, perhaps assuming that astronauts live off dried food, prepackaged and sent from Earth. There certainly is an element of that but travellers to the International Space Station have over recent years been able to feast on fresh salad grown in special units on board. Unfortunately, recent research suggests that pathogenic bacteria and fungi can contaminate the ‘greens’ even in space. It’s been at least three years that astronauts have been able to eat fresh lettuce and other leafy items along with tortillas and powdered coffee.. Specially designed chambers on board allow them to grown plants under carefully controlled temperature, water and lights to ensure a successful harvest.  There is however an issue that the ISS is a relatively closed environment and so it is easy for bacteria and fungi to spread and astronauts to get ill.  The International Space Station stretches out in an image captured by astronauts aboard the SpaceX Crew Dragon Ende

Is the Habitable Zone Really Habitable?

The water that life knows and needs, the water that makes a world habitable, the water that acts as the universal solvent for all the myriad and fantastically complicated chemical reactions that make us different than the dirt and rocks, can only come in one form: liquid. The vast, vast majority of the water in our universe is unsuitable for life. Some of it is frozen, locked in solid ice on the surface of a world too distant from its parent star or bound up in a lonely, wayward comet. The rest is vaporized, existing as a state of matter where molecules lose their electron companions, boundless and adrift through the great nebular seas that dot the galaxies, or ejected completely into the great voids between them. Either way, that water exists only one molecule at a time, at a temperature of over a million degrees yet its density so low that you could pass through it and mistake it for the cold, hard vacuum of space itself. No, for water to be liquid it must exist in special place a

NASA Wants to Put a Massive Telescope on the Moon

As part of the Artemis Program, NASA intends to establish all the necessary infrastructure to create a “sustained program of lunar exploration and development.” This includes the Lunar Gateway, an orbiting habitat that will enable regular trips to and from the surface, and the Artemis Base Camp , which will permit astronauts to remain there for up to two months. Multiple space agencies are also planning on creating facilities that will take advantage of the “quiet nature” of the lunar environment, which includes high-resolution telescopes. As part of this year’s NASA Innovative Advance Concepts (NIAC) Program, a team from NASA’s Goddard Space Flight Center has proposed a design for a lunar Long-Baseline Optical Imaging Interferometer (LBI) for imaging at visible and ultraviolet wavelengths. Known as the Artemis-enabled Stellar Imager (AeSI), this proposed array of multiple telescopes was selected for Phase I development. With a little luck, the AeSI array could be operating on the f

New Types of Hidden Stars Seen for the First Time

In the early days of telescopic astronomy, you could only focus on one small region of the sky at a time. Careful observations had to be done by hand, and so much of the breakthrough work centered around a particular object in the sky. A nebula or galaxy, quasar or pulsar. But over the years we’ve been able to build telescopes capable of capturing a wide patch of sky all at once, and with automation, we can now map the entire sky. Early sky surveys took years to complete, but many modern sky surveys can look for changes on the order of weeks or days. This ability to watch for changes across the sky is changing the way we do astronomy, and it is beginning to yield some interesting results. As a case in point, an infrared sky survey is revealing hidden stars we hadn’t noticed before. In a series of papers published in the Monthly Notices of the Royal Astronomical Society , the authors have analyzed data from a decade-long survey called the Visible and Infrared Survey Telescope (VISTA).