Space News & Blog Articles

Astrobiologists continue to work towards determining which biosignatures might be best to look for when searching for life on other worlds. The most common idea has been to search for evidence of plants that use the green pigment chlorophyll, like we have on Earth. However, a new paper suggests that bacteria with purple pigments could flourish under a broader range of environments than their green cousins. That means current and next-generation telescopes should be looking for the emissions of purple lifeforms.

“Purple bacteria can thrive under a wide range of conditions, making it one of the primary contenders for life that could dominate a variety of worlds,” said Lígia Fonseca Coelho, a postdoctoral associate at the Carl Sagan Institute (CSI) and first author of “Purple is the New Green: Biopigments and Spectra of Earth-like Purple Worlds,” published in the Monthly Notices of the Royal Astronomical Society: Letters.

According to NASA’s Exoplanet Archive, 5612 extrasolar planets have been found so far, as of this writing, and another 10,000 more are considered planetary candidates, but have not yet been confirmed. Of all those, there are just over 30 potentially Earth-like worlds, planets that lie in their stars’ habitable zones where conditions are conducive to the existence of liquid water on surface.

But Earth-like has a broad meaning, ranging from size, mass, composition, and various chemical makeups. While being within a star’s habitable zone certainly means there’s the potential for life, it doesn’t necessarily mean that life could have emerged there, or even if it did, the life on that world might look very different from Earth.

“While oxygenic photosynthesis gives rise to modern green landscapes, bacteriochlorophyll-based anoxygenic phototrophs can also colour their habitats and could dominate a much wider range of environments on Earth-like exoplanets,” Coelho and team wrote in their paper. “While oxygenic photosynthesis gives rise to modern green landscapes, bacteriochlorophyll-based anoxygenic phototrophs can also colour their habitats and could dominate a much wider range of environments on Earth-like exoplanets.”

Planetary nebula are some of nature’s most stunning visual displays. The name is confusing since they’re the remains of stars, not planets. But that doesn’t detract from their status as objects of captivating beauty and intense scientific study.

Like all planetary nebula, the Southern Ring Nebula is the remnant of a star like our Sun. As these stars age, they will eventually become red giants, expanding and shedding layers of gas out into space. Eventually, the red giant becomes a white dwarf, a stellar remnant bereft of fusion that emanates whatever residual thermal energy it has without ever generating anymore. The white dwarf lights up the shells of gas expelled earlier, and we get to enjoy the show.

When the long-awaited JWST started delivering images, the Southern Ring Nebula (NGC 3132) was one of its first targets. It was one of five objects that made up the telescope’s first science results. The JWST’s images revealed something surprising about NGC 3132: it has two stars. The white dwarf is in the center of NGC 3132 and its companion is between 40 to 60 AU away, about the same distance as Pluto is from the Sun.

Researchers wanted to understand more about the Southern Ring Nebula’s structure. The JWST works in the infrared and can image warm hydrogen in the nebula. But to get a more complete image of the nebula, a team of researchers from the Rochester Institute of Technology (RIT) turned to the Submillimeter Array (SMA). The SMA can sense the cooler CO (carbon monoxide) in the nebula beyond the JWST’s reach. It sensed CO’s presence and measured its velocity and the velocities of other molecules.

The research is published in The Astrophysical Journal titled “The Molecular Exoskeleton of the Ring-like Planetary Nebula NGC 3132.” Professor Joel Kastner from the RIT School of Physics and Astronomy is the lead author.

The venerable Hubble Space Telescope is like a gift that keeps on giving. Not only is it still making astronomical discoveries after more than thirty years in operation. It is also making discoveries by accident! Thanks to an international team of citizen scientists, with the help of astronomers from the European Space Agency (ESA) and some machine learning algorithms, a new sample of over one thousand asteroids has been identified in Hubble‘s archival data. The methods used represent a new approach for finding objects in decades-old data that could be applied to other datasets as well.

The research team was led by Pablo García-Martín, a researcher with the Department of Theoretical Physics at the Autonomous University of Madrid (UAM). It included members from the ESA, NASA’s Jet Propulsion Laboratory (JPL), the Astronomical Institute of the Romanian Academy, the University of Craiova, the Université Côte d’Azur, and Bastion Technologies. The paper that describes their findings, “Hubble Asteroid Hunter III. Physical properties of newly found asteroids,” recently appeared in Astronomy & Astrophysics.

Ask any astronomers and they will tell you that asteroids are material left over from the formation of the Solar System ca. 4.5 billion years ago. These objects come in many shapes in sizes, ranging from peddle-sized rocks to planetoids. Observing these objects is challenging since they are faint and constantly in motion as they orbit the Sun. Because of its rapid geocentric orbit, Hubble can capture wandering asteroids thanks to the distinct curved trails they leave in Hubble exposures. As Hubble orbits Earth, its point of view changes while observing asteroids following their orbits.

Hubble image of the barred spiral galaxy UGC 12158, with streaks left by photobombing asteroids. Credit: NASA, ESA, P. G. Martín (AUM)/J. DePasquale (STScI)/A. Filippenko (UC Berkeley)

Asteroids have also been known to “photobomb” images acquired by Hubble of distant cosmic objects like UGC 12158 (see image above). By knowing Hubble’s position when it took exposures of asteroids and measuring the curvature of the streaks they leave, scientists can determine the asteroids’ distances and estimate the shapes of their orbits. The ability to do this with large samples allows astronomers to test theories about Main Asteroid Belt formation and evolution. As Martin said in a recent ESA Hubble press release: