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    Category Astronomy/Space

    Star Formation in Distant Galaxies by the James Webb Space Telescope

    February 7, 2023, Categories  Astronomy/Space

    Galaxies at a great distance
    The James Webb Space Telescope captured this image of a galaxy cluster (SMACS0723). The five zoomed in galaxies are so far away that we observe them as they were when the Universe was between one and five billion years old. Today the Universe is 13.7 billion years old. Credit: Image adapted from image release by NASA, ESA, CSA, STScI.

    Thanks to the James Webb Space Telescope’s first images of galaxy clusters, researchers have, for the very first time, been able to examine very compact structures of star clusters inside galaxies, so-called clumps. In a paper published in the Monthly Notices of the Royal Astronomical Society, researchers from Stockholm University have studied the first phase of star formation in distant galaxies.

    “The galaxy clusters we examined are so massive that th...

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    Hubble directly measures Mass of a Lone White Dwarf

    February 7, 2023, Categories  Astronomy/Space

    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

    February 2, 2023, Categories  Astronomy/Space

    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

    February 2, 2023, Categories  Astronomy/Space

    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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