Astronomy and Planetary Science Thread

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A young, sun-like star may hold warnings for life on Earth

Astronomers spying on a stellar system located dozens of lightyears from Earth have, for the first time, observed a troubling fireworks show: A star, named EK Draconis, ejected a massive burst of energy and charged particles much more powerful than anything scientists have seen in our own solar system.

Still, Notsu noted that huge mass ejections may have been much more common in the early years of the solar system. Gigantic coronal mass ejections, in other words, could have helped to shape planets like Earth and Mars into what they look like today.

“The atmosphere of present-day Mars is very thin compared to Earth’s,” Notsu said. “In the past, we think that Mars had a much thicker atmosphere. Coronal mass ejections may help us to understand what happened to the planet over billions of years.”


Related paper:

Probable detection of an eruptive filament from a superflare on a solar-type star

Abstract
Solar flares are often accompanied by filament/prominence eruptions (~104 K and ~1010−11 cm−3), sometimes leading to coronal mass ejections that directly affect the Earth’s environment1,2. ‘Superflares’ are found on some active solar-type (G-type main-sequence) stars3,4,5, but the filament eruption–coronal mass ejection association has not been established. Here we show that our optical spectroscopic observation of the young solar-type star EK Draconis reveals evidence for a stellar filament eruption associated with a superflare. This superflare emitted a radiated energy of 2.0 × 1033 erg, and a blueshifted hydrogen absorption component with a high velocity of −510 km s−1 was observed shortly afterwards. The temporal changes in the spectra strongly resemble those of solar filament eruptions. Comparing this eruption with solar filament eruptions in terms of the length scale and velocity strongly suggests that a stellar coronal mass ejection occurred. The erupted filament mass of 1.1 × 1018 g is ten times larger than those of the largest solar coronal mass ejections. The massive filament eruption and an associated coronal mass ejection provide the opportunity to evaluate how they affect the environment of young exoplanets/the young Earth6 and stellar mass/angular momentum evolution7.

 

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Maybe the water droplets we saw from the escape craft at the end of ALIEN had some basis in reality, if not the the space rain on Bruce Willis' face as he neared Earth atop the asteroid. It reminds me a bit of Louis Frank's idea of small comets.
 

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Maybe the water droplets we saw from the escape craft at the end of ALIEN had some basis in reality, if not the the space rain on Bruce Willis' face as he neared Earth atop the asteroid. It reminds me a bit of Louis Frank's idea of small comets.
It certainly offers an explanation as to why we find water nearly everywhere we look. Not puddles of the stuff obviously but ices and deposits seem to be all over the place.
 

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The existence of carbon dioxide (CO2) cold traps on the Moon has been confirmed, offering a potential resource for future exploration of the lunar surface, according to a new paper by Planetary Science Institute Senior Scientist Norbert Schorghofer.


Related paper:

Carbon Dioxide Cold Traps on the Moon

Abstract
Water ice is expected to be trapped in permanently cold regions near the lunar poles. Other ices (“super-volatiles”) are trapped at lower temperatures, close to the lowest temperatures measured within the lunar permanently shadowed regions (PSRs). Here, the thermal stability of solid carbon dioxide in the south polar region is determined by analysis of 11 years of temperature measurements by Diviner, a radiometer onboard the Lunar Reconnaissance Orbiter. Sublimation rates averaged over a draconic year are far lower than peak sublimation rates. Small spatially contiguous pockets of CO2 ice stability are found in the craters Amundsen, Haworth, de Gerlache, and others, over a cumulative area of roughly 200 km2. The LCROSS probe impacted one of those pockets and released CO2, serving as validation of the thermal stability calculations. Future surface missions can utilize this highly localized resource for the production of fuel, steel, and biological materials.

 

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In June of 2018, telescopes around the world picked up a brilliant blue flash from the spiral arm of a galaxy 200 million light years away. The powerful burst appeared at first to be a supernova, though it was much faster and far brighter than any stellar explosion scientists had yet seen. The signal, procedurally labeled AT2018cow, has since been dubbed simply “the Cow,” and astronomers have catalogued it as a fast blue optical transient, or FBOT — a bright, short-lived event of unknown origin.

Now an MIT-led team has found strong evidence for the signal’s source. In addition to a bright optical flash, the scientists detected a strobe-like pulse of high-energy X-rays. They traced hundreds of millions of such X-ray pulses back to the Cow, and found the pulses occurred like clockwork, every 4.4 milliseconds, over a span of 60 days.

Based on the frequency of the pulses, the team calculated that the X-rays must have come from an object measuring no more than 1,000 kilometers wide, with a mass smaller than 800 suns. By astrophysical standards, such an object would be considered compact, much like a small black hole or a neutron star.


View: https://youtu.be/NSZIewPb0zU
 

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A Harsh Test of Far-Field Scrambling with the Habitable Zone Planet Finder and the Hobby Eberly Telescope

The Habitable zone Planet Finder (HPF) is a fiber fed precise radial velocity spectrograph at the 10 m Hobby Eberly Telescope (HET). Due to its fixed altitude design, the HET pupil changes appreciably across a track, leading to significant changes of the fiber far-field illumination. HPF's fiber scrambler is designed to suppress the impact of these illumination changes on the radial velocities -- but the residual impact on the radial velocity measurements has yet to be probed on sky. We use GJ 411, a bright early type (M2) M dwarf to probe the effects of far-field input trends due to these pupil variations on HPF radial velocities (RVs). These large changes (∼ 2x) in pupil area and centroid present a harsh test of HPF's far-field scrambling. Our results show that the RVs are effectively decoupled from these extreme far-field input changes due to pupil centroid offsets, attesting to the effectiveness of the scrambler design. This experiment allows us to test the impact of these changes with large pupil variation on-sky, something we would not easily be able to do at a conventional optical telescope. While the pupil and illumination changes expected at these other telescopes are small, scaling from our results enables us to estimate and bound these effects, and show that they are controllable even for the new and next generation of RV instruments in their quest to beat down instrumental noise sources towards the goal of a few cm/s.


Source: https://phys.org/news/2021-12-evidence-coronal-cool-small-m-dwarf.amp
 

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Supermassive black hole at the center of our galaxy may have a friend

Finally, if there are two massive black holes orbiting each other at the galactic center, as my team suggests is possible, they will emit gravitational waves. Since 2015, the LIGO-Virgo observatories have been detecting gravitational wave radiation from merging stellar-mass black holes and neutron stars. These groundbreaking detections have opened a new way for scientists to sense the universe.

Any waves emitted by our hypothetical black hole pair will be at low frequencies, too low for the LIGO-Virgo detectors to sense. But a planned space-based detector known as LISA may be able to detect these waves which will help astrophysicists figure out whether our galactic center black hole is alone or has a partner.

 

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Venus could be becoming "more habitable" after evidence of bacterial "lifeforms" were found in its clouds, scientists have said.

Researchers from Cardiff University, MIT and Cambridge University have suggested the planet, which is 47.34m kilometres (29.42m miles) from Earth, could have the colourless gas made up of nitrogen and hydrogen that is also known as ammonia in its clouds.


The scientists have modelled a set of chemical processes to show how a cascade of chemical reactions would neutralise surrounding droplets of sulfuric acid if there were any traces of ammonia.

This would then result in the acidity of the clouds dropping from -11 to zero, and although this is still very acidic on the pH scale, it would be at a level that life could potentially survive at.

Co-author of the study Dr William Bains, from Cardiff University's School of Physics and Astronomy, said: "We know that life can grow in acid environments on Earth, but nothing as acid as the clouds of Venus were believed to be.
 

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Mysterious Dust-emitting Object Orbiting TIC 400799224

We report the discovery of a unique object of uncertain nature -- but quite possibly a disintegrating asteroid or minor planet -- orbiting one star of the widely separated binary TIC 400799224. We initially identified the system in data from TESS Sector 10 via an abnormally-shaped fading event in the light curve (hereafter 'dips'). Follow-up speckle imaging determined that TIC 400799224 is actually two stars of similar brightness at 0.62" separation, forming a likely bound binary with projected separation of ~300 au. We cannot yet determine which star in the binary is host to the dips in flux. ASAS-SN and Evryscope archival data show that there is a strong periodicity of the dips at ~19.77 days, leading us to believe that an occulting object is orbiting the host star, though the duration, depth, and shape of the dips vary substantially. Statistical analysis of the ASAS-SN data shows that the dips only occur sporadically at a detectable threshold in approximately one out of every three to five transits, lending credence to the possibility that the occulter is a sporadically-emitted dust cloud. The cloud is also fairly optically thick, blocking up to 37% or 75% of the light from the host star, depending on the true host. Further observations may allow for greater detail to be gleaned as to the origin and composition of the occulter, as well as to a determination of which of the two stars comprising TIC 400799224 is the true host star of the dips.

 

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Astronomers find ‘deformed’ planet that isn’t round for the first time

Astronomers have found a “deformed” exoplanet shaped like a rugby ball for the first time.

The planet has been stretched out and squashed down by the tidal forces between it and Wasp-103, the distant star around which it orbits. That star is about 200 degrees hotter and 1.7 times bigger than our Sun.

The unusual planet known as Wasp-103b was spotted using new data from Cheops, the European Space Agency’s mission to find exoplanets, which was combined with existing information from the Hubble and Spitzer space elescopes.

 

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Cool Worlds - We Discovered a New Exomoon Candidate! A Survey of 70 Cool Gas Giants:

View: https://youtu.be/Blej3YvveCI

An exomoon survey of 70 cool giant exoplanets and the new candidate Kepler-1708 b-i

Abstract
Exomoons represent a crucial missing puzzle piece in our efforts to understand extrasolar planetary systems. To address this deficiency, we here describe an exomoon survey of 70 cool, giant transiting exoplanet candidates found by Kepler. We identify only one exhibiting a moon-like signal that passes a battery of vetting tests: Kepler-1708 b. We show that Kepler-1708 b is a statistically validated Jupiter-sized planet orbiting a Sun-like quiescent star at 1.6 au. The signal of the exomoon candidate, Kepler-1708 b-i, is a 4.8σ effect and is persistent across different instrumental detrending methods, with a 1% false-positive probability via injection–recovery. Kepler-1708 b-i is ~2.6 Earth radii and is located in an approximately coplanar orbit at ~12 planetary radii from its ~1.6 au Jupiter-sized host. Future observations will be necessary to validate or reject the candidate.


It’s another sub-Neptune exomoon candidate around a cool gas giant.
 
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Flyaway

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Plato exoplanet mission gets green light for next phase

Plato, ESA’s next-generation planet hunting mission, has been given the green light to continue with its development after the critical milestone review concluded successfully on 11 January 2022.

The review verified the maturity of the complete space segment (spacecraft platform and payload module), confirming the solidity of the spacecraft-to-payload interfaces, the payload schedule with particular focus on the series production of the 26 cameras, and the robustness of the spacecraft schedule. Plato will use the 26 cameras to discover and characterise exoplanets that orbit stars similar to our Sun.
 

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China's FAST telescope detects over 500 new pulsars

GUIYANG, Dec. 15 (Xinhua) -- Using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), also dubbed as the "China Sky Eye," scientists have identified over 500 new pulsars since October 2017.

Pulsars, or fast-spinning neutron stars, originate from the imploded cores of massive dying stars through supernova explosions. With their high density and fast rotation, they are an ideal laboratory for studying the laws of physics in extreme environments.

Using FAST, scientists also detected a total of 1,652 independent bursts from a single repeating fast radio burst (FRB) source, code-named FRB121102, said Li Di, chief scientist of the telescope and a researcher with the National Astronomical Observatories under the Chinese Academy of Sciences.

It is the largest set of FRB events ever detected in history, Li said, adding that these results were published in the journal Nature in October.

Scientists believe it may help clarify the origins of the so-called "mysterious signals from deep space."

Li said they had received around 200 observation applications from 16 countries since March when FAST officially opened to the world.

Located in a naturally deep and round karst depression in southwest China's Guizhou Province, FAST started formal operation in January 2020. It is believed to be the world's most sensitive radio telescope.

 

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The supermassive black hole lurking at the heart of the Milky Way – Sagittarius A*, or Sgr A* for short – contains about 4.3 million solar masses, and, as it turns out, nearly all of the mass at the very center of the galaxy.

An international team of astronomers, using the Gemini North telescope in Hawaii and the European Southern Observatory’s Very Large Telescope, measured the position and velocity of four stars in the immediate neighbourhood of Sgr A* and found them to be moving in the manner one would expect if the black hole accounted for 99.9 percent of the matter at the center of the Milky Way.


View: https://youtu.be/XanbXkQCg6I
 

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NASA’s Transiting Exoplanet Survey Satellite has now identified more than 5,000 possible exoplanet candidates – TESS Objects of Interest, or TOIs – mostly from a faint star search led by Michelle Kunimo, a postdoc at MIT. While TOIs are, by definition, unconfirmed, astronomers are confident additional observations will add to TESS’s list of known exoplanets.

“This time last year, TESS had found just over 2,400 TOIs. Today, TESS has reached more than twice that number — a huge testament to the mission and all the teams scouring the data for new planets. I’m excited to see thousands more in the years to come!”

It will take additional observations by astronomers around the world to confirm whether a TOI is, in fact, an actual exoplanet. Three such confirmations were announced at the American Astronomical Society’s winter meeting earlier this month.

A team led by Samuel Grunblatt, a postdoctoral fellow at the American Museum of Natural History and the Flatiron Institute in New York City, found three gas giants in TOI data. The planets have some of the shortest-period orbits around subgiant or giant stars yet found and one of them, TOI-2337b, likely will be consumed by its host star in less than a million years.

 

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Something in Earth's cosmic neighborhood is emitting weird signals of a kind we've never seen before.
Just 4,000 light-years away, something is flashing radio waves. For roughly 30 to 60 seconds, every 18.18 minutes, it pulses brightly, one of the most luminous objects in the low-frequency radio sky. It matches the profile of no known astronomical object, and astronomers are gobsmacked. They have named it GLEAM-X J162759.5-523504.3.

”This object was appearing and disappearing over a few hours during our observations," said astrophysicist Natasha Hurley-Walker of the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) in Australia.
"That was completely unexpected. It was kind of spooky for an astronomer because there's nothing known in the sky that does that. And it's really quite close to us – about 4,000 light-years away. It's in our galactic backyard."
At the moment, they believe it is most likely one of two things, both 'dead' stars: a type of ultra-magnetic neutron star called a magnetar, or, with a smaller likelihood, a highly magnetized white dwarf. If it's the former, it would be the first time we've detected a magnetar with a very long pulsation period, known as an ultra-long period magnetar.


A radio transient with unusually slow periodic emission

Abstract
The high-frequency radio sky is bursting with synchrotron transients from massive stellar explosions and accretion events, but the low-frequency radio sky has, so far, been quiet beyond the Galactic pulsar population and the long-term scintillation of active galactic nuclei. The low-frequency band, however, is sensitive to exotic coherent and polarized radio-emission processes, such as electron-cyclotron maser emission from flaring M dwarfs1, stellar magnetospheric plasma interactions with exoplanets2 and a population of steep-spectrum pulsars3, making Galactic-plane searches a prospect for blind-transient discovery. Here we report an analysis of archival low-frequency radio data that reveals a periodic, low-frequency radio transient. We find that the source pulses every 18.18 min, an unusual periodicity that has, to our knowledge, not been observed previously. The emission is highly linearly polarized, bright, persists for 30–60 s on each occurrence and is visible across a broad frequency range. At times, the pulses comprise short-duration (<0.5 s) bursts; at others, a smoother profile is observed. These profiles evolve on timescales of hours. By measuring the dispersion of the radio pulses with respect to frequency, we have localized the source to within our own Galaxy and suggest that it could be an ultra-long-period magnetar.

 

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