One of the critical aspects of exoplanet habitability is the long-term stability of the stars they orbit. Some stars are extremely massive and blast through their hydrogen fuel in only a few million years. Rigel, the blue supergiant in Orion, is an example of one of these. It will shine for only about 10 million years. That's not much time for life to arise on planets.
It feels like every time we publish an article about an exciting discovery of a potential biosignature on a new exoplanet, we have to publish a follow-up one a few months later debunking the original claims. That is exactly how science is supposed to work, and part of our job as science journalists is to report on the debunking as well as the original story, even if it might not be as exciting. In this particular case, it seems the discovery of dimethyl sulfide in the atmosphere of exoplanet K2-18 b was a false alarm, according to a new paper available in pre-print form on arXiv by Luis Welbanks of Arizona State University and his co-authors.
This is Part 1 in a series on the physics of free will.
Gravitational Lensing is a vital tool for astronomers to observe objects that are too distant or faint (or both) to be resolved by current instruments. This method leverages a prediction from Einstein's Theory of General Relativity, namely that massive objects alter the curvature of spacetime. When a "lens" comes into view, its gravitational field bends and amplifies light from more distant objects. In a recent study, a team of astronomers used a combination of ground-based telescopes to discover the first spatially resolved, gravitationally lensed supernova.
The platypus is one of evolution's loveable, oddball animals. The creature seems to defy well-understood rules of biology by combining physical traits in a bizarre way. They're egg-laying mammals with duck bills and beaver-like tails, and the males have venomous spurs on their hind feet. In that regard, it's only fitting that astronomers describe some newly-discovered oddball objects as 'Astronomy's Platypus.'
We may not know what dark matter is, but that hasn't stopped scientists from trying to understand its role in the Universe. The Lambda-Cold Dark Matter (CDM) model is the standard model that explains the cosmos the best, although it's not the only model. It makes a number of predictions about dark matter and researchers look for opportunities to test those predictions. The results either help confirm or deny the model.
It feels like every week now we’re writing a new article about how 3I/ATLAS is not an alien technology. But it’s worth re-iterating, and perhaps taking a look at the methodology we used to prove that statement. A new paper, available in pre-print form on arXiv from Sofia Sheikh of the SETI Institute and her co-authors, details how one specific instrument - the Allen Telescope Array (ATA) - contributed to that effort.
Stars and planets are inextricably linked. They form together and stars shape the fate of planets. Stars create the dusty protoplanetary disks that give birth to planets of all kinds. And when a star dies, planets are either blown apart, swallowed, or doomed to spend an eternity in cold and darkness.
One of the main questions in exoplanet science concerns M dwarfs (red dwarfs) and the habitability of exoplanets that orbit them. These stars are known for their prolific and energetic flaring, and that's a problem. M dwarfs are so small that their habitable zones are in tight proximity to them, putting any potentially habitable planets in the direct line of fire of all this dangerous flaring.
Nearly every galaxy has a supermassive black hole in its core. Whether the black hole forms first and then the galaxy around it—or the other way around—is still a matter of some debate, but we know the evolution of both are deeply connected. We can use that relationship to study the black holes.
So far, humanity has yet to find its first “exomoon” - a Moon orbiting a planet outside of the solar system. But that hasn’t been for lack of trying. According to a new paper by Thomas Winterhalder of the European Southern Observatory and his co-authors available as a pre-print on arXiv, the reason isn’t because those Moons don’t exist, but simply because we lack the technology to detect them. They propose a new “kilometric baseline interferometer” that can detect moons as small as the Earth up to 200 parsecs (652 light years) away.
The X-Ray Imaging and Spectroscopy Mission (XRISM), a joint mission between the Japanese Aerospace Exploration Agency (JAXA) and NASA, launched on Sept. 7th, 2023. Its advanced imaging filters and spectrometers were designed to study black holes and neutron stars and detect the hot plasma in the intergalactic medium. Alongside the European Space Agency’s (ESA) X-ray Multi-Mirror Mission Newton (XMM-Newton) and NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR), XRISM has provided the sharpest-ever X-ray spectrum of the iconic MCG–6-30-15.
The discovery of Gravitational Waves (GWs) in 2015 confirmed a prediction made by Einstein's Theory of General Relativity and led to a revolution in astronomy. These waves are produced when massive, compact objects (such as black holes and neutron stars) merge, creating ripples in spacetime that can be detected millions of light-years away. A decade later, researchers from the University of Amsterdam (UvA) have proposed how GWs could be used to investigate an enduring cosmological mystery - the existence of Dark Matter.
It's quite a challenge to make an Earth-like world. You need enough mass to hold an atmosphere and generate a good magnetic field, but not so much mass that you hang on to light elements such as hydrogen and helium. You also need to be close enough to your star that you remain comfortably warm, but not so warm that all your water gets baked away. And then you need an abundance of short-lived radioisotopes (SLRs).
The Milky Way has a long and fascinating history that extends back to the early Universe - ca. 13.61 billion years ago. In that time, it has evolved considerably and merged with other galaxies to become the galaxy we see today. In a recent study, a team of Canadian astronomers has created the most detailed reconstruction of how the Milky Way evolved from its earliest phases to its current phase. Using data provided by the James Webb Space Telescope (JWST), the team examined 877 galaxies whose masses and properties closely match what astronomers expect the Milky Way looked like over time ("Milky Way twins").
The Sun is not only our closest stellar neighbor, it's also the star we understand the most. As we've observed it over the centuries, we've learned that the Sun is not an immortal constant. It goes through active and quiet cycles, it has become warmer over geologic time scales, and it occasionally batters the Earth with solar flares. We've generally thought that other main sequence stars behave in much the same way, but when it comes to solar flares, that isn't always true.
Size matters when it comes to telescopes. The bigger they are, the farther they can see. Prioritizing constructing large ones is therefore high on the priority list for many observational organizations. But doing so comes at a cost, and not just in terms of money. Finding a suitable site can be a challenge, and that has been particularly true for the effort to build a 30-meter telescope in the Northern hemisphere. A new paper, available in pre-print on arXiv by Francesco Coti Zelati of the Spanish Institute of Space Sciences in Barcelona and his co-authors, makes the argument for building it at the Roque de los Muchachos Observatory in La Palma in the Canary Islands.
For decades, scientists have observed the cosmos with radio antennas to visualize the dark, distant regions of the Universe. This includes the gas and dust of the interstellar medium (ISM), planet-forming disks, and objects that cannot be observed in visible light. In this field, the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile stands out as one of the world's most powerful radio telescopes. Using its 66 parabolic antennas, ALMA observes the millimeter and submillimeter radiation emitted by cold molecular clouds from which new stars are born.
Hidden behind veils of interstellar dust lies Westerlund 1, the most massive, luminous, and nearby super star cluster in the Milky Way. Despite being a stellar powerhouse just 12,000 light-years away in the constellation Ara, it remains invisible to the naked eye. Yet this stellar congregation has just revealed something remarkable: it’s actively blowing an enormous bubble of gamma rays into the space beneath our galaxy’s disk.
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