Heavens

A new paper has shown how large structures in the distribution of galaxies in the Universe provide the most precise tests of dark energy and cosmic expansion yet.

The study uses a new method based on a combination of cosmic voids - large expanding bubbles of space containing very few galaxies - and the faint imprint of sound waves in the very early Universe, known as baryon acoustic oscillations (BAO), that can be seen in the distribution of galaxies. This provides a precise ruler to measure the direct effects of dark energy driving the accelerated expansion of the Universe.

Computer simulations conducted by astrophysicists at Tohoku University in Japan, have revealed a new theory for the origin of supermassive black holes. In this theory, the precursors of supermassive black holes grow by swallowing up not only interstellar gas, but also smaller stars as well. This helps to explain the large number of supermassive black holes observed today.

The Sun is the brightest object in the sky and has been studied for hundreds of years, but it continues to hide some secrets. We all know that the visible Sun is extremely hot, at temperature of about 5500 degrees. Surprisingly, on top of this sits a layer of gas, called the corona, which is at a temperature of almost 2 million degrees, over 300 times hotter than the surface of the Sun! What heats up the corona to 2 million degrees is one of the most challenging puzzles about the Sun and no one found a satisfactory answer to this until date.

A team of researchers, led by astrophysicist Sumner Starrfield of Arizona State University (ASU), has combined theory with both observations and laboratory studies and determined that a class of stellar explosions, called classical novae, are responsible for most of the lithium in our galaxy and solar system.

The results of their study have been recently published in the Astrophysical Journal of the American Astronomical Society.

The halo that surrounds our own Milky Way galaxy is much hotter than scientists once believed - and it may not be unique among galaxies.

The new findings were presented at the annual meeting of the American Astronomical Society, held online this week because of the COVID-19 pandemic.

In previous work, researchers at The Ohio State University found that parts of the Milky Way's halo - the hazy fog of dust, gas and dark matter that surrounds some galaxies - was at least 10 times hotter than anyone had known before.

Astronomers using European Southern Observatory (ESO) telescopes have discovered giant spots on the surface of extremely hot stars hidden in stellar clusters. Not only are these stars plagued by magnetic spots, some also experience superflare events, explosions of energy several million times more energetic than similar eruptions on the Sun. The findings, published today in Nature Astronomy, help astronomers better understand these puzzling stars and open doors to resolving other elusive mysteries of stellar astronomy.

Maunakea, Hawaii - Determined to find a needle in a cosmic haystack, a pair of astronomers time traveled through archives of old data from W. M. Keck Observatory on Mauankea in Hawaii and old X-ray data from NASA's Chandra X-ray Observatory to unlock a mystery surrounding a bright, lensed, heavily obscured quasar.

The existence of a planet the size of Earth around the closest star in the solar system, Proxima Centauri, has been confirmed by an international team of scientists including researchers from the University of Geneva (UNIGE). The results, which you can read all about in the journal Astronomy & Astrophysics, reveal that the planet in question, Proxima b, has a mass of 1.17 earth masses and is located in the habitable zone of its star, which it orbits in 11.2 days.

Active galactic nuclei (AGNs) play a major role in galaxy evolution. Astronomers from the University of Groningen and Netherlands Institute for Space Research have now used a record-sized sample of galaxies to confirm that galaxy mergers have a positive effect on igniting AGNs. They were able to compile about ten times more images of merging galaxies than previous studies by using a machine-learning algorithm. The results were published on 27 May in the journal Astronomy & Astrophysics.

The NASA/ESA Hubble Space Telescope was used to conduct a three-year study of the crowded, massive and young star cluster Westerlund 2. The research found that the material encircling stars near the cluster's centre is mysteriously devoid of the large, dense clouds of dust that would be expected to become planets in a few million years. Their absence is caused by the cluster's most massive and brightest stars that erode and disperse the discs of gas and dust of neighbouring stars.

What is the origin of the asteroids Bennu and Ryugu, and of their spinning-top shape? An international research team led by Patrick Michel, a CNRS researcher at the Laboratoire Lagrange (CNRS/Observatoire de la Côte d'Azur/Université Côte d'Azur) and Ronald-Louis Ballouz from the University of Arizona, proposes an answer to this question in an article published in Nature Communications on May 27, 2020.

New Haven, Conn. -- A new, Yale-led study shows that some supermassive black holes actually thrive under pressure.

It has been known for some time that when distant galaxies --and the supermassive black holes within their cores -- aggregate into clusters, these clusters create a volatile, highly pressurized environment. Individual galaxies falling into clusters are often deformed during the process and begin to resemble cosmic jellyfish.

EVANSTON, Ill. -- Move aside, AT2018COW. There is a new astronomical transient in the universe, and it is faster, heavier and brighter at radio wavelengths than its mysterious predecessors.

After astronomers visually spotted a bright burst in a tiny galaxy 500 million lightyears away from Earth in 2016, a Northwestern University-led team has determined that the anomaly is the third fast blue optical transient (FBOT) ever captured in radio- and X-ray wavelengths.

Astronomers have found two objects that, added to a strange object discovered in 2018, constitute a new class of cosmic explosions. The new type of explosion shares some characteristics with supernova explosions of massive stars and with the explosions that generate gamma-ray bursts (GRBs), but still has distinctive differences from each.

The Milky Way, the whiteish strip of light which is prominent in both the summer and the winter skies, is the densest part of the disc of the Galaxy which we are inside. However, over very long periods it has not always looked the same, and its evolution is a challenge to current astrophysics.

To study this evolution, ESA's Gaia mission is measuring the luminosities, positions, motions, and the chemical composition of a large number of individual stars in our Galaxy.