Category Astronomy/Space

Hubble directly measures Mass of a Lone White Dwarf

Black background with stars. Image center: blue-white star (LAWD 37) surrounded by horizontal rectangle that indicates the area highlighted in an inset box. Inset box illustrates the path of LAWD 37 and the position of the background star relative to it.
This graphic shows how microlensing was used to measure the mass of a white dwarf star. The dwarf, called LAWD 37, is a burned-out star in the center of this Hubble Space Telescope image. Though its nuclear fusion furnace has shut down, trapped heat is sizzling on the surface at 180,000 degrees Fahrenheit, causing the stellar remnant to glow fiercely. The inset box plots how the dwarf passed in front of a background star in 2019. The wavy blue line traces the dwarf’s apparent motion across the sky as seen from Earth. Though the dwarf is following a straight trajectory, the motion of Earth orbiting the Sun imparts an apparent sinusoidal offset due to parallax. (The star is only 15 light-years away. Therefore, it is moving at a faster rate against the stellar background...
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Numerical Simulations of Planetesimal Formation Reproduce Key Properties of Asteroids, Comets

Numerical simulations of planetesimal formation reproduce key properties of asteroids, comets
Comparison between the predictions by Polak and Klahr for the mass distribution of asteroids (red circles), compared with observations (white circles). The horizontal axis shows the size of the asteroids in question, and the vertical axis shows the fraction of the total mass of the pebble cloud that ends up in asteroids larger or equal to the chosen size value. If the total mass were to end up in a single asteroid, that asteroid would have been 152 km in diameter. Both in the prediction and according to the observations, 84% of the total asteroid mass ends up in objects between 90 km and 152 km in diameter. Overall, the primordial asteroids follow a normal (Gaussian) distribution (blue line) in mass with a most likely size of 125 km...
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The Bubbling Universe: A previously unknown Phase Transition in the Early Universe

The bubbling universe: A previously unknown phase transition in the early universe
AI generated illustration of colliding bubbles in early universe. Credit: Birgitte Svennevig, University of Southern Denmark

What happened shortly after the universe was born in the Big Bang and began to expand? Bubbles occurred and a previously unknown phase transition happened, according to particle physicists.

Think of bringing a pot of water to the boil: As the temperature reaches the boiling point, bubbles form in the water, burst and evaporate as the water boils. This continues until there is no more water changing phase from liquid to steam.

This is roughly the idea of what happened in the very early universe, right after the Big Bang, 13.7 billion years ago.

The idea comes from particle physicists Martin S...

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Evidence that Saturn’s moon Mimas is a Stealth Ocean World

Saturn moon Mimas and a graph of two options of its geology
Courtesy of NASA/JPL/SSI/SwRI

Simulations suggest that Saturn’s smallest, innermost moon could have an expanding, geologically young ocean. When a Southwest Research Institute scientist discovered surprising evidence that Saturn’s smallest, innermost moon could generate the right amount of heat to support a liquid internal ocean, colleagues began studying Mimas’ surface to understand how its interior may have evolved. Numerical simulations of the moon’s Herschel impact basin, the most striking feature on its heavily cratered surface, determined that the basin’s structure and the lack of tectonics on Mimas are compatible with a thinning ice shell and geologically young ocean.

“In the waning days of NASA’s Cassini mission to Saturn, the spacecraft identified a curious libration, or os...

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