Space Stories: Dinosaur Dust, Missing Stars, and SETI Signals

Posted on by onespaceman2000
Image (Credit): The end of the dinosaurs. (NYT, Roger Harris/Science Source)

Here are some recent stories of interest.

—Royal Observatory of Belgium: “Dust Played a Major Role in Dinosaur Demise“

Fine dust from pulverized rock generated by the Chicxulub impact likely played a dominant role in global climate cooling and the disruption of photosynthesis following the event. This is suggested by a new study published in Nature Geoscience, in which researchers Cem Berk Cenel, Özgür Karatekin and Orkun Temel of the Royal Observatory of Belgium contributed.

—Express: “Astronomers Trying to Unravel Mystery of Three Stars that Suddenly Disappeared from Sky“

A team of Spanish astronomers is leading the investigation into one of stargazing’s most perplexing mysteries. Three bright stars photographed in the night sky above southern California in 1952 vanished just an hour later. Generations of scientists have sought to explain the rare phenomenon over the past half-century, but nothing has yet convinced the community. Researchers at the Centre for Astrobiology (CAB) in Madrid tried to solve the riddle of the “triple transient” that has “remained absent from telescope exposures for 71 years” in a new paper published online.

—Sci.News: “New Study Sets Clearer Bounds on Search for Technosignatures from Extraterrestrial Intelligences“

A stable-frequency transmitter with relative radial acceleration to a receiver will show a change in received frequency over time, known as a ‘drift rate.’ For a transmission from an exoplanet, astronomers must account for multiple components of drift rate: the exoplanet’s orbit and rotation, the Earth’s orbit and rotation, and other contributions. Understanding the drift rate distribution produced by exoplanets relative to Earth, can help scientists constrain the range of drift rates to check in a Search for Extraterrestrial Intelligence (SETI) project to detect radio technosignatures, and help them decide validity of signals-of-interest, as they can compare drifting signals with expected drift rates from the target star. In a new study, University of California, Los Angeles astronomer Megan Grace Li and colleagues modeled the drift rate distribution for over 5,300 confirmed exoplanets, using parameters from the NASA Exoplanet Archive.

Study Findings: A Planetary Collision Afterglow and Transit of the Resultant Debris Cloud

Posted on by onespaceman2000
Image (Credit): Artist’s rendering of two colliding planets. (NASA)

Nature abstract of the study findings:

Planets grow in rotating disks of dust and gas around forming stars, some of which can subsequently collide in giant impacts after the gas component is removed from the disk. Monitoring programmes with the warm Spitzer mission have recorded substantial and rapid changes in mid-infrared output for several stars, interpreted as variations in the surface area of warm, dusty material ejected by planetary-scale collisions and heated by the central star: for example, NGC 2354–ID8, HD 166191 and V488 Persei. Here we report combined observations of the young (about 300 million years old), solar-like star ASASSN-21qj: an infrared brightening consistent with a blackbody temperature of 1,000 Kelvin and a luminosity that is 4 percent that of the star lasting for about 1,000 days, partially overlapping in time with a complex and deep, wavelength-dependent optical eclipse that lasted for about 500 days. The optical eclipse started 2.5 years after the infrared brightening, implying an orbital period of at least that duration. These observations are consistent with a collision between two exoplanets of several to tens of Earth masses at 2–16 astronomical units from the central star. Such an impact produces a hot, highly extended post-impact remnant with sufficient luminosity to explain the infrared observations. Transit of the impact debris, sheared by orbital motion into a long cloud, causes the subsequent complex eclipse of the host star.

Citation: Kenworthy, M., Lock, S., Kennedy, G. et al. A planetary collision afterglow and transit of the resultant debris cloud. Nature 622, 251–254 (2023).
https://doi.org/10.1038/s41586-023-06573-9

Study-related stories:

Podcasts: The Search for Intelligent Life in the Galaxy

Posted on by onespaceman2000
Credit: University of Arizona Press

Last month there were a few podcasts worth checking out on our search for intelligent life elsewhere in the galaxy.

The first was an episode from The Planetary Society’s podcast Planetary Radio titled Alone but not lonely with Louis Friedman. Dr. Friedman, co-founder of The Planetary Society, is very skeptical about the Search for Extraterrestrial Life (SETI) efforts, believing we are most likely alone in the universe in terms of intelligent life and, even if there were other lifeforms out there, they are too far away for us to engage with it. That said, he does have ideas for studying exoplanets, such as a solar gravity lens that could significantly magnify the objects we are viewing.

He also discusses The Planetary Society’s solar sail spacecraft and how it could be left floating in our solar system awaiting and then inspecting incoming objects from outside our solar system. Its a great idea. You can read more about his ideas in his latest book (shown above).

The second episode is from Cool Worlds Lab titled Adam Frank – Technosignatures, Semantic Information, Galactic Colonization. Dr. Frank, a Professor of Physics and Astronomy at Rochester University, is much more optimistic about our ability to eventually find intelligent life in the galaxy and discusses the methods being used today to do so (going beyond the decades old SETI approach). He agrees with Dr. Friedman that we are dealing with great distances that may preclude human travel to these locations.

Dr. Frank even discusses the idea that maybe we were visited by alien civilizations in the past and we don’t know it because we were not here at the time. He discussed this very topic an much more in an earlier Scientific American article, “Alone in a Crowded Milky Way,” stating:

Perhaps long, long ago aliens came and went. A number of scientists have, over the years, discussed the possibility of looking for artifacts that might have been left behind after such visitations of our solar system. The necessary scope of a complete search is hard to predict, but the situation on Earth alone turns out to be a bit more manageable. In 2018 another of my colleagues, Gavin Schmidt of the NASA Goddard Institute for Space Studies, together with Frank, produced a critical assessment of whether we could even tell if there had been an earlier industrial civilization on our planet.

As fantastic as it may seem, Schmidt and Frank argue—as do most planetary scientists—that it is actually very easy for time to erase essentially all signs of technological life on Earth. The only real evidence after a million or more years would boil down to isotopic or chemical stratigraphic anomalies—odd features such as synthetic molecules, plastics or radioactive fallout. Fossil remains and other paleontological markers are so rare and so contingent on special conditions of formation that they might not tell us anything in this case.

It’s a terrific article that also argues that we may be in a part of the galaxy that gets fewer visitors. I recommend listening to the podcast and then reading the article (or checking out his book on the topic, shown below).

Credit: HarperCollinsPublishers

Space Stories: Psyche Ready to Go, Interesting Exoplanets, and Protecting Astronaut Health

Posted on by onespaceman2000
Image (Credit): Artist’s rendering of NASA’s Psyche mission approaching the asteroid Psyche. (NASA)

Here are some recent stories of interest.

—Universe.com: “NASA’s Psyche Now Set to Launch October 12“

With just under two weeks until its planned launch, NASA’s Psyche mission has been rescheduled. As per a NASA blog post, the agency along with SpaceX are now aiming for liftoff on October 12 at 10:16 A.M. EDT from the Kennedy Space Center in Florida — the first of several NASA science missions that will ride to space on a Falcon Heavy Rocket. The mission was originally set to launch October 5.

—Trottier Institute for Research on Exoplanets: “UdeM-Led Study of Exoplanet TRAPPIST-1 b Reveals New Insights into its Atmosphere and Star“

A team of astronomers has made an important leap forward in our understanding of the intriguing TRAPPIST-1 exoplanetary system. Not only has their research shed light on the nature of TRAPPIST-1 b, the exoplanet orbiting closest to the system’s star, but it has also shown the importance of parent stars when studying exoplanets. The findings, published today in Astrophysical Journal Letters, shed light on the complex interplay between stellar activity and exoplanet characteristics.

—NASA: “NASA Funds Eight Studies to Protect Astronaut Health on Long Missions“

NASA is funding eight new studies aimed at better understanding how the human body reacts to spaceflight. These studies will be done on Earth without the need for samples and data from astronauts. Collectively, these studies will help measure physiological and psychological responses to physical and mental challenges that astronauts may encounter during spaceflight. With this information, NASA may be better able to mitigate risks and protect astronaut health and performance during future long-duration missions to the International Space Station, the Moon, Mars, and beyond. 

JWST Spots a Promising Exoplanet

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Image (Credit): Artist’s concept showing exoplanet K2-18 b. (Illustration: NASA, CSA, ESA, J. Olmsted (STScI), Science: N. Madhusudhan (Cambridge University))

The exoplanet, some 120 light-years away, has caught the attention scientists using the James Webb Space Telescope (JWST). K2-18 b, about 8.6 times as massive as Earth, has carbon-bearing molecules in its atmosphere, including methane and carbon dioxide. This could mean the exoplanet has a hydrogen-rich atmosphere and a water ocean-covered surface (called a Hycean exoplanet).

Exoplanets of this size, between the size of Earth and Neptune, are called “sub-Neptune” exoplanets. These are the most most common type of exoplanet found to date in our galaxy.

Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper announcing these results, stated:

Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere…Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations.

You can read more about this discovery at the NASA site.