Astronomy

The Ingenuity Mars helicopter's flying days may be over, but its influence will be felt far into the future.

In coming decades, major groundwater sources may become economically unfeasible — this could raise food prices and shift diets, among other impacts

In coming decades, major groundwater sources may become economically unfeasible — this could raise food prices and shift diets, among other impacts

Using a new approach, scientists have successfully frozen and thawed brain organoids and cubes of brain tissue from someone with epilepsy, which could enable better research into neurological conditions

Using a new approach, scientists have successfully frozen and thawed brain organoids and cubes of brain tissue from someone with epilepsy, which could enable better research into neurological conditions

Heat seems to trigger a sweep of changes in immune system molecules, although researchers disagree on what they might mean

How do you get ready for flying to the moon? The Artemis 2 astronauts practiced a day in space ahead of their historic liftoff in 2025 to see what living in the Orion spacecraft is like.

Sierra Space’s Dream Chaser is set to make its inaugural trip to orbit to deliver supplies to the International Space Station

Video: 00:00:29

Over the weekend of 10–12 May 2024, Earth was struck by the largest solar storm in more than a decade. While many of us enjoyed colourful auroras lighting up Earth’s protective atmosphere, spacecraft had to endure being buffeted by incredibly strong solar winds and electromagnetic radiation.  

Positioned between the Sun and Earth, the ESA/NASA Solar and Heliospheric Observatory (SOHO) caught the entire solar outburst on camera. The Sun can be seen spewing out clouds of particles, with an extremely large burst sent to Earth on 11 May. The bright spots on the left and right are Jupiter and Venus. 

This video was taken by SOHO’s LASCO instrument, a coronagraph made up of a telescope with a disc blocking the centre of view. By blocking out the direct light coming from the Sun, the instrument can see light from the surrounding corona.  

SOHO is not the only ESA spacecraft studying solar activity and space weather. ESA’s Directorates of Science, Human and Robotic Exploration, Earth Observation, Operations, and Technology, Engineering and Quality all have missions and/or other activities directly connected with this topic. Together, they form the ESA Heliophysics observatory or more musically, ESA’s Heliophysics Orchestra.  

New research into weed reveals how a lemon-scented terpene can ease anxiety without reducing the high.

Animal life on Earth existed for over half a billion years before hominins hit the scene – a complex combination of environmental changes, innovations in technology and competition may have led to us

Animal life on Earth existed for over half a billion years before hominins hit the scene – a complex combination of environmental changes, innovations in technology and competition may have led to us

The Arctic could see a surge of jellyfish as climate change leads to warmer waters and less ice – a process known as “jellification”

The Arctic could see a surge of jellyfish as climate change leads to warmer waters and less ice – a process known as “jellification”

The Galaxy, the Jet, and a Famous Black Hole

What would it look like to circle a black hole?

When stars exhaust their hydrogen fuel at the end of their main sequence phase, they undergo core collapse and shed their outer layers in a supernova. Whereas particularly massive stars will collapse and become black holes, stars comparable to our Sun become stellar remnants known as “white dwarfs.” These “dead stars” are extremely compact and dense, having mass comparable to a star but concentrated in a volume about the size of a planet. Despite being prevalent in our galaxy, the chemical makeup of these stellar remnants has puzzled astronomers for years.

For instance, white dwarfs consume nearby objects like comets and planetesimals, causing them to become “polluted” by trace metals and other elements. While this process is not yet well understood, it could be the key to unraveling the metal content and composition (aka. metallicity) of white dwarf stars, potentially leading to discoveries about their dynamics. In a recent paper, a team from the University of Colorado Boulder theorized that the reason white dwarf stars consume neighboring planetesimals could have to do with their formation.

The research team consisted of Tatsuya Akiba, a Ph.D. candidate at UC Boulder with the Joint Institute for Laboratory Astrophysics (JILA) at UC Boulder. He was joined by Selah McIntyre, an undergraduate student in the Department of Chemistry, and Ann-Marie Madigan, a JILA Fellow and a professor in the Department of Astrophysical and Planetary Sciences. Their research was reported in a paper titled “Tidal Disruption of Planetesimals from an Eccentric Debris Disk Following a White Dwarf Natal Kick,” which recently appeared in The Astrophysical Journal.

Planetesimal orbits around a white dwarf. Initially, every planetesimal has a circular, prograde orbit. The kick forms an eccentric debris disk with prograde (blue) and retrograde orbits (orange). Credit: Steven Burrows/Madigan group

Despite their prevalence in our galaxy, the chemical makeup of white dwarfs has puzzled astronomers for years. The presence of heavy metal elements like silicon, magnesium, and calcium on the surfaces of many of these stellar remnants defies what astronomers consider conventional stellar behavior. “We know that if these heavy metals are present on the surface of the white dwarf, the white dwarf is dense enough that these heavy metals should very quickly sink toward the core,” said Akiba in a recent JILA press release. “So, you shouldn’t see any metals on the surface of a white dwarf unless the white dwarf is actively eating something.”

Madigan’s research group at JILA focuses on the gravitational dynamics of white dwarfs and how these affect surrounding material. For their study, the team created computer models that simulated a white dwarf experiencing a rare phenomenon known to occur during its formation. This consisted of an asymmetric mass loss caused by a “natal kick” that altered its motion and the dynamics of the surrounding material. As Professor Madigan explained:

“Simulations help us understand the dynamics of different astrophysical objects. So, in this simulation, we throw a bunch of asteroids and comets around the white dwarf, which is significantly bigger, and see how the simulation evolves and which of these asteroids and comets the white dwarf eats. Other studies have suggested that asteroids and comets, the small bodies, might not be the only source of metal pollution on the white dwarf’s surface. So, the white dwarfs might eat something bigger, like a planet.”

In 80% of their test runs, the team observed that the orbits of comets and planetesimals within 30 to 240 AU (the distance between the Sun and Neptune and well into the Kuiper Belt) of the star became elongated and aligned. They also found that in about 40% of their simulations, the consumed planetesimals came from retrograde orbits. Lastly, they extended their simulations to 100 million years after formation and found that these planetesimals still had elongated orbits and moved as one coherent unit.

Artist’s illustration of crystals forming within a white dwarf. Credit: University of Warwick/Mark Garlick

These new findings also shed light on the origin, chemistry, and future evolution of stars, including our Solar System. In about 5 billion years, our Sun will exit its main sequence phase and grow to become a Red Giant. Roughly 2 billion years later, it will blow off its outer layers in a supernova, leaving behind a white dwarf remnant. Looking ahead, the researchers hope to take their simulations to greater scales to examine how white dwarfs interact with larger planets. These simulations could reveal what will become of the outer planets in our Solar System once our Sun is in its “dead” phase. Said Madigan:

“This is something I think is unique about our theory: we can explain why the accretion events are so long-lasting. While other mechanisms may explain an original accretion event, our simulations with the kick show why it still happens hundreds of millions of years later. The vast majority of planets in the universe will end up orbiting a white dwarf. It could be that 50% of these systems get eaten by their star, including our own solar system. Now, we have a mechanism to explain why this would happen.”

Further Reading: JILA, AJL

The post White Dwarfs are Often Polluted With Heavier Elements. Now We Know Why appeared first on Universe Today.

The one-day courses were particularly beneficial to those pupils with worse mental health problems initially

The one-day courses were particularly beneficial to those pupils with worse mental health problems initially

We have discovered over 5,000 planets around other star systems. Amongst the veritable cosmic menagerie of exoplanets, it seems there is a real shortage of Neptune-sized planets close to their star. A new paper just published discusses a Saturn-sized planet close to its host star which should be experiencing mass loss, but isn’t. Studying this world offers a new insight into exoplanet formation across the Universe. 

Exoplanets really are fascinating. Ever-since their discovery the race has been on to discover and catalogue them. It gives us a great opportunity to explore a far more statistically significant set of data to understand planetary system formation rather than just studying are own system.

The absence of Neptune-mass exoplanets closer to the host stars in exoplanetary systems has been a bit of a mystery. Their lack has been attributed to one of two things; photoevaporation – mass is lost through ionisation of gas by radiation which then disperses away form the ionising source or high-eccentricity migration – where the planets move through the planetary system as we have seen with some of the giant planets in our Solar System. 

NASA’s Voyager 2 spacecraft captured these views of Uranus (on the left) and Neptune (on the right) during its flybys of the planets in the 1980s.

To distinguish between these two possibilities a team of astronomers led by Morgan Saidel from the California Institute of Technology investigated the origins of TOI-1259 A b which is a Saturn mass exoplanet. It is in a 3.48 day orbit around a K type star at a distance putting it on the edge of the so called Neptune desert. A region around a star wherein there are no Neptune sized planets. 

In the case of TOI-1259 A b, it is thought that its low density means it is especially vulnerable to photoevaporation. Transit methods were used, observing with the Hale Telescope at Palomar Observatory in the 1083nm helium line to probe the upper levels of the atmosphere. The near-infrared spectrograph on Keck II was also used and showed that there was indeed atmosphere escaping but at a rate lower than expected. The rate of gas loss through photoevaporation (1010.325 g s?1)is too low to significantly have altered the planets mass even if it had formed in its current location.

The hexagonal primary mirror of the Keck II telescope. (Credit: SiOwl. A Wikimedia Commons image under a Creative Commons Attribution 3.0 Unported liscense).

Instead, the team believe that the presence of a white dwarf companion (TOI-1259 B) may have caused the planet to migrate inwards after formation. Analysing the orbital parameters of the planet and the binary star system reveal that high-eccentricity migration is a far more likely explanation. 

Planetary migrations of this sort may leave a trace through accretion of elements in the planetary atmosphere. Quantities of H2O, CO, CO2 , SO2 and CH4 should be at detectable levels in the atmosphere of TOI-1259 A b.  If they are observed through transmission spectroscopic studies, will reveal where in protoplanetary disk the planet formed in. Further studies will be required to finally answer this question. 

Source : Atmospheric Mass Loss from TOI-1259 A b, a Gas Giant Planet With a White Dwarf Companion

The post Saturn-Sized Exoplanet Isn’t Losing Mass Quickly Enough appeared first on Universe Today.