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Category: space

The most pristine star yet found in the known universe

An unusual team of astronomers used Sloan Digital Sky Survey-V (SDSS-V) data and observations on the Magellan telescopes at Carnegie Science’s Las Campanas Observatory in Chile to discover the most pristine star in the known universe, called SDSS J0715-7334. Their work is published in Nature Astronomy.

Led by the University of Chicago’s Alexander Ji—a former Carnegie Observatories postdoctoral fellow—and including Carnegie astrophysicist Juna Kollmeier—who leads SDSS, now in its fifth generation—the research team identified a star from just the second generation of celestial objects in the cosmos, which formed just a few billion years after the universe began.

“These pristine stars are windows into the dawn of stars and galaxies in the universe,” Ji explained. Several of his and Kollmeier’s co-authors on the paper are undergraduate students from UChicago, whom Ji brought to Las Campanas on an observing trip for spring break last year. “My first visit to LCO is where I really fell in love with astronomy, and it was special to share such a formative experience with my students.”

High nickel concentrations in Martian bedrock point to potential biosignatures

In 2024, NASA’s Perseverance rover found surprising levels of Nickel in the Martian bedrock of an ancient river channel, called Neretva Vallis, which flowed into the Jezero crater. A new study, published in Nature Communications, has taken a closer look at the data collected from the region and researchers are seeing what could be remnants of ancient Martian life.

Although nickel is not typically thought of as a major component of human life, it is important in many microbial metabolism functions. For example, nickel is a requirement for the Wood-Ljungdahl (W-L) pathway—an ancient, energy-efficient anaerobic process utilized by bacteria and archaea to fix carbon dioxide. The reverse of this process also requires nickel and has been observed in some species of sulfate-reducing bacteria, for the decomposition of organic matter.

“In particular, Ni is an essential component of enzymes used by methanogenic archaea and many bacterial species. Ni is vital to the metabolism of methanogenic organisms, such that a decrease in the Ni content of Earth’s oceans in the Archean is hypothesized to have caused a collapse in atmospheric methane preceding the Great Oxidation Event,” explain the study authors.

Terraforming Mars: Modeling engineered aerosols to warm the planet

Whenever humans arrive on Mars, they’re going to find it a difficult place to exist. Mars is cold, with an average surface temperature of −55°C; temperatures can plunge to −125°C with dust storms lasting months; its atmosphere is very thin and almost all carbon dioxide; and all the water is frozen and mixed with ice made of CO2. Oh, and solar radiation will be hazardous on Mars’ surface since the planet has no ozone layer to block ultraviolet radiation, especially so during solar flares. Disneyland it is not.

New Martians will need to live underground until, someday, maybe, Mars can be terraformed to, if not quite looking like Earth, at least a planet more hospitable to fragile human creatures.

There are arguments for and against terraforming Mars. If humans do terraform, one of the first suggestions is to increase Mars’ greenhouse effect by melting the CO2-ice caps.

NASA’s Curiosity Rover Sees Martian ‘Spiderwebs’ Up Close

For about six months, NASA’s Curiosity Mars rover has been exploring a region full of geologic formations called boxwork, low ridges standing roughly 3 to 6 feet (1 to 2 meters) tall with sandy hollows in between. Crisscrossing the surface for miles, the formations suggest ancient groundwater flowed on this part of the Red Planet later than scientists expected. This possibility raises new questions about how long microbial life could have survived on Mars billions of years ago, before rivers and lakes dried up and left a freezing desert world behind.

The boxwork formations look like giant spiderwebs when viewed from space. To explain the shapes, scientists have proposed that groundwater once flowed through large fractures in the bedrock, leaving behind minerals. Those minerals then strengthened the areas that became ridges while other portions without mineral reinforcement were eventually hollowed out by wind.

Methane’s Elaborate Phases and Where to Find Them

A systematic exploration of the phase diagram of methane resolves inconsistencies of earlier studies, with potential ramifications for our understanding of planetary interiors.

As a gas, methane is very simple. But as a liquid and as a solid, it is perplexingly complex. Ambiguity has long plagued our observations and measurements of its structure at different pressure–temperature combinations. Yet, understanding methane’s phase diagram is vital for predicting its behavior deep within our and other planets. In a tour de force contribution Mengnan Wang at the University of Edinburgh in the UK and her colleagues have now charted the turbulent seas of the methane phase diagram [1]. By comprehensively mapping its phases and melting curve, they have resolved the legion of discrepancies of earlier studies.

Methane—one of the simplest of all molecules—is sometimes the subject of flatulence jokes (of which it is odorlessly innocent) but is also a powerful driver of climate change on Earth (of which it is very guilty [2]). The extraction of gaseous methane from Earth drives multibillion-dollar industries, which use the molecule both as a fuel and as a source of hydrogen. Out in the Solar System, methane in planetary atmospheres absorbs red light, which makes Uranus and Neptune shine blue, while icy methane damaged by radiation paints dwarf planets red.

First carbon-enhanced metal-poor stars discovered in Milky Way’s companion

Using the Baryons Oscillation Spectroscopic Survey (BOSS) spectrograph, astronomers have discovered five new carbon-enhanced metal-poor stars in the Large Magellanic Cloud (LMC). This is the first time such stars have been identified in this galaxy. The discovery was reported in a paper published January 15 on the arXiv pre-print server.

Metal-poor stars are rare objects, as only a few thousand stars with iron abundances [Fe/H] below-2.0 have been discovered to date. Expanding the still-short list of metal-poor stars is of high importance for astronomers, as such objects have the potential to improve our knowledge of the chemical evolution of the universe.

Observations show that a significant fraction of these stars exhibit a large overabundance of carbon; therefore, they are known as carbon-enhanced metal-poor (CEMP) stars.

Helical liquid crystals can flip light’s chirality under ultralow electric fields

The direction in which the electromagnetic field of circularly polarized light rotates can be easily reversed by applying a voltage, RIKEN researchers have demonstrated. This could enable a new generation of optical devices based on circularly polarized light. The work is published in two papers in the journal Advanced Materials.

Polarized sunglasses produce light that is polarized along a single direction. But some special devices can generate light with a polarization that rotates as the light propagates. Such circularly polarized light is useful for many applications, including spectroscopy, satellite communications, stereoscopy and microscopy.

For some applications, it would be useful to switch between clockwise and anticlockwise circularly polarized light. However, this handedness is locked into the molecular structure. Known as the material’s chirality, it is used to produce the circularly polarized light. And reversing that requires a lot of energy.

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