AAS NOVA — Research Highlights 2020
Posted: Fri Jan 17, 2020 6:13 pm
APOD and General Astronomy Discussion Forum
https://asterisk.apod.com/
Susanna Kohler wrote:
It’s nearly eight billion years in the future.
The Sun, having exhausted its source of fuel, has dramatically expanded into a red giant and then puffed off its outer layers, leaving its dense, scalding hot core exposed. This core — a white dwarf — initially clocks in at nearly 100,000 K (180,000 °F), bathing its surroundings in harsh extreme-ultraviolet (EUV) radiation at levels that are up to a million times brighter than the present-day Sun.
Earth and the other inner, rocky planets were swallowed up by the ballooning Sun long ago. But how have the giant planets of our solar system — Jupiter, Saturn, Uranus, and Neptune — fared since this unavoidable apocalypse? ...
bystander wrote: ↑Thu Jan 23, 2020 3:48 pm Giant Planets in a Post-Apocalyptic Solar System
NOVA | American Astronomical Society | 2020 Jan 22Susanna Kohler wrote:
It’s nearly eight billion years in the future.
The Sun, having exhausted its source of fuel, has dramatically expanded into a red giant and then puffed off its outer layers, leaving its dense, scalding hot core exposed. This core — a white dwarf — initially clocks in at nearly 100,000 K (180,000 °F), bathing its surroundings in harsh extreme-ultraviolet (EUV) radiation at levels that are up to a million times brighter than the present-day Sun.
Earth and the other inner, rocky planets were swallowed up by the ballooning Sun long ago. But how have the giant planets of our solar system — Jupiter, Saturn, Uranus, and Neptune — fared since this unavoidable apocalypse? ...
Susanna Kohler wrote:
Not all laboratory astrophysics occurs in labs down here on Earth; sometimes, the lab is in space! A new study has used a space laboratory to confirm a new atomic process — with far-reaching implications. ...
Susanna Kohler wrote:
New evidence deepens the mystery of fast radio bursts (FRBs), the brief flashes of radio emission stemming from unknown sources beyond our galaxy. Scientists have now discovered faint repeat bursts from one of the brightest FRBs, previously thought to have been a one-off event. ...
Tarini Konchady wrote:
Water is critical to life as we know it on Earth. So naturally, finding evidence of liquid water on a planet in its star’s habitable zone is extremely relevant to searches for extraterrestrial life. Thus far, we’ve only discovered water vapor in the atmospheres of massive, short-period gas giants — but new observations of sub-Neptune K2-18b have now changed that. ...
Susanna Kohler wrote:
Black holes come in a variety of sizes — from a mass of a few Suns, to millions or even billions of solar masses. As these vastly different black holes feast on accreting matter, do they behave in the same way? ...
Susanna Kohler wrote:
What do we know about the second object to visit us from another stellar system? Detailed Hubble images have given us plenty to consider! ...
Susanna Kohler wrote:
What might we learn about the Sun if we could fly a spacecraft close enough to dip down and skim through its atmosphere? Thanks to the Parker Solar Probe, we don’t have to speculate! ...
Susanna Kohler wrote:
The globular cluster Omega Centauri makes for an impressive sight — millions of stars gravitationally bound into a beautiful sphere, its core alight from the glow of densely packed bodies. A recent study has unveiled a new discovery at the heart of this cluster: five long-anticipated pulsars. ...
Tarini Konchady wrote:
Studying star formation in the early universe can give us clues about what the universe was like when the earliest massive galaxies were forming. How efficiently were these first galaxies making stars only a billion years after the Big Bang? ...
Susanna Kohler wrote:
Some young stars seem to spend a brief portion of their lives undergoing dramatic, flaring outbursts. A new study has used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to get the closest look yet at one of these systems — possibly identifying the cause of the flares. ...
Susanna Kohler wrote:
Python, one of the foremost high-level programming languages, has played a growing role in the analysis of astronomical data. With the recent release of a new software package, SunPy, it’s now easier than ever for solar physicists to use Python as well.
Susanna Kohler wrote:
Thanks to the Laser Interferometer Gravitational-wave Observatory (LIGO), we now know that black holes in our distant universe sometimes find each other in a dramatic inspiral and collision, releasing a burst of gravitational-wave emission that we can detect here on Earth.
But what happened earlier in these black holes’ lives to bring them to this point? A new study explores the possibility that LIGO’s black holes once lay at the centers of very small galaxies — until those galaxies collided. ...
Susanna Kohler wrote:
Though stars within the same cluster all typically form around the same time, they don’t all evolve in the same way. A recent study has carefully explored a population of particularly unusual, straggling stars in the old open cluster Collinder 261. ...
Tarini Konchady wrote:
We can only really see what’s going on at the surface of a star. However, the motions within stellar interiors show themselves as subtle variations in the star’s brightness, and with the dense observations of planet-finding missions, we can pick up these variations at very fine levels. ...
Susanna Kohler wrote:
Whether or not a planet lies in its star’s habitable zone is commonly used to gauge its ability to host life. But what about non-habitable-zone planets that have sources of heat besides starlight? ...
Susanna Kohler wrote:
Some of the most spectacular images to come out of observatories like the Atacama Large Millimeter/submillimeter Array (ALMA) or the Very Large Telescope (VLT) are detailed views of protoplanetary disks. These disks of gas and dust around young stars aren’t just smooth and featureless; instead, they exhibit arcs, rings, gaps, and spirals. What causes this impressive array of structure? ...
Tarini Konchady wrote:
An X-ray binary consists of a dense compact object that strips material off its stellar companion, producing X-rays in the process. These binaries are surrounded by radiating accretion disks of infalling material, but they also sometimes fling matter out in powerful relativistic jets. What can their infrared emission tell us about the speed of these jets? ...
Susanna Kohler wrote:
In October of 2018, we wrote about a new project to study fast radio bursts (FRBs) — brief, energetic flashes of light from beyond our galaxy. At the time, we knew of about 30 FRB sources; the new project by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope in British Columbia promised to dramatically increase that number.
Now, a year and a half later, we can see the impressive progress made: CHIME has already detected around 700 bursts from FRB sources! Included among those is the collaboration’s latest announcement: nine new repeating sources. ...
Susanna Kohler wrote:
What happens when the large-scale drama of a violent galaxy merger plays out on small scales for a pair of dwarf galaxies? New observations document the scene of a recent dwarf-galaxy collision. ...
Susanna Kohler wrote:
One of our goals with the soon-to-launch James Webb Space Telescope (JWST) is to better characterize the atmospheres of exoplanets. But will clouds get in the way of our chances? ...
Susanna Kohler wrote:
In case you missed the news in January: the Laser Interferometer Gravitational-Wave Observatory (LIGO) has detected its second merger of two neutron stars — probably. In a recent publication, the collaboration details the interesting uncertainties and implications of this find. ...
Susanna Kohler wrote:
At the end of 2019, we announced the launch of a new publication in the American Astronomical Society’s journal family: The Planetary Science Journal (PSJ), a peer-reviewed journal that covers “all aspects of investigation of the solar system and other planetary systems.”
Now, PSJ has officially published its first issue. Read on for a look at the first articles included, and follow the links to the full open-access articles if you’d like to learn more!
Origin of a Battered Lunar Layer
The surface of the Moon has been constantly bombarded by small, rocky bodies over its lifetime, fracturing its crust down to depths of perhaps 20 km. Planetary Science Institute scientists James Richardson and Oleg Abramov have now modeled this process to better understand how the upper megaregolith — the battered layer of lunar dirt 1–3 km deep that lies just below the Moon’s surface — formed.
Modeling the Formation of the Lunar Upper Megaregolith Layer ~ James E. Richardson, Oleg Abramov
- Planetary Science Journal 1(1):2 (2020 June) DOI: 10.3847/PSJ/ab7235
Will Asteroid Ejecta Arrive at Earth?
In 2022, the Double Asteroid Redirection Test (DART) spacecraft will fire a projectile into the binary asteroid (65803) Didymos to explore how we can deflect asteroids for planetary defense. Scientist Paul Wiegert (The University of Western Ontario, Canada) wonders whether some of the ejected material might escape the Didymos system and make its way to Earth — where we could examine it, but where it also might pose a risk to spacecraft. Wiegert finds that, based on the parameters of the mission, little DART-ejected material will reach our planet, and most will only arrive after thousands of years.
On the Delivery of DART-ejected Material from Asteroid (65803) Didymos to Earth ~ Paul Wiegert
- Planetary Science Journal 1(1):3 (2020 June) DOI: 10.3847/PSJ/ab75bf
Observing Mercury’s Exosphere at Twilight
Due to Mercury’s proximity to the Sun, ground-based observations of the planet’s exosphere — its tenuous outermost atmosphere — are best conducted at twilight. A team of scientists led by Carl Schmidt (Boston University and LATMOS, France) reports on how results from a new instrument, the Rapid Imaging Planetary Spectrograph, are mitigating some of the challenges of observing at twilight, like windshake, fluctuations in seeing and atmospheric transmission, and guiding problems.
The Rapid Imaging Planetary Spectrograph: Observations of Mercury’s Sodium Exosphere in Twilight ~ Carl A. Schmidt et al
- Planetary Science Journal 1(1):4 (2020 June) DOI: 10.3847/PSJ/ab76c9
Characterization of Nearby Asteroids and Comets
The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft has been conducting an infrared survey to detect and characterize asteroids and comets since its reactivation in 2013 December. Led by Joseph Masiero (Jet Propulsion Laboratory/Caltech), a team of scientists now reports on the 374 near-Earth objects and 11,607 main-belt asteroids the mission detected in its fourth and fifth years.
Asteroid Diameters and Albedos from NEOWISE Reactivation Mission Years 4 and 5 ~ Joseph R. Masiero et al
- Planetary Science Journal 1(1):5 (2020 June) DOI: 10.3847/PSJ/ab7820
Learning about Fluid Stability from Jupiter’s Jets
Inviscid shear instability is a common type of fluid instability that governs the dynamics of everything from meandering jet streams in atmospheres and oceans to the formation of planets in protoplanetary disks. Scientist Timothy Dowling (University of Louisville) has used observations from the two Voyager flybys, the Galileo entry probe, the Cassini flyby, and the Juno orbiter to study this instability in Jupiter’s zonal jets — the atmospheric flows in the light bands that encircle the planet.
Jupiter-style Jet Stability ~ Timothy E. Dowling
- Planetary Science Journal 1(1):6 (2020 June) DOI: 10.3847/PSJ/ab789d
Getting Rid of Mercury’s Mantle
Why does Mercury have such an unusually large iron core? One hypothesis is that Mercury formed with a silicate-to-iron ratio closer to that of Earth, but its silicate mantle was stripped off by a giant impact in its past, leaving behind the large fraction of iron. Scientists Christopher Spalding (Yale University) and Fred Adams (University of Michigan) show that the primordial solar wind — which was stronger than the solar wind of present day — could have produced enough drag to push the silicate ejecta away and prevent the material from reaccreting onto Mercury’s surface.
The Solar Wind Prevents Reaccretion of Debris after Mercury’s Giant Impact ~ Christopher Spalding, Fred C. Adams
- Planetary Science Journal 1(1):7 (2020 June) DOI: 10.3847/PSJ/ab781f
Tarini Konchady wrote:
Fast radio bursts (FRBs) are brief radio signals that last on the order of milliseconds. They appear to be extragalactic, coming from small, point-like areas on the sky. Some FRBs are one-off events, while others are periodic or “repeating”. The sources of FRBs are still unknown, but binary neutron star systems might be a piece of the puzzle. ...