Stars

Arp 283 (NGC 2799 and NGC 2798) (Immagine ESA/Hubble & NASA, SDSS, J. Dalcanton Acknowledgement: Judy Schmidt (Geckzilla))

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A photo taken by the Hubble Space Telescope shows Arp 283, which is not a single object but a pair of galaxies classified as NGC 2798 (on the right) and NGC 2799 (on the left). Astronomer Halton Arp put this pair in his catalog of peculiar galaxies because they are two interacting galaxies, which means they’re affected by each other’s force of gravity. Arp 283 was compared to a waterspout with stars from NGC 2799 appearing to fall towards NGC 2798 like drops of water. In the distant future, the two galaxies could merge.

Betelgeuse seen by the SPHERE instrument in December 2019 (Image ESO/M. Montargès et al.)

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An article published in “The Astrophysical Journal” reports a study of the star Betelgeuse that concludes that it’s smaller and closer to Earth compared to previous measurements. A team of researchers led by Dr. Meridith Joyce of the Australian National University (ANU) used observations conducted using the Coriolis satellite’s SMEI instrument before it started dimming and three different modeling methods to conclude that its radius is about 764 times the Sun’s, its mass is between 16.5 and 19 times the Sun’s and its distance is about 548 light-years from the Earth.

Artist's concept of tidal disruption event (Image ESO/M. Kornmesser)

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An article published in the journal “Monthly Notices of the Royal Astronomical Society” reports a study on a tidal disruption event cataloged as AT2019qiz in which it was possible to see the phases in which a star was destroyed by a supermassive black hole. A team of researchers led by astrophysicist Matt Nicholl from the British University of Birmingham used various telescopes including ESO’s Very Large Telescope (VLT) and New Technology Telescope (NTT) and NASA’s Spitzer space observatory to follow this event, which lasted about six months, with the star’s “spaghettification” and about half of it swallowed by the black hole.

Some of the galaxies observed in the GAMA project

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An article published in the journal “Monthly Notices of the Royal Astronomical Society” proposes a new way of studying star formation in galaxies. A team of researchers led by Sabine Bellstedt of the International Center for Radio Astronomy Research (ICRAR) developed a technique to analyze the metallicity, which is the abundance of elements heavier than helium, of galaxies. Those elements are produced by stars so their amount increases over time and the more massive ones produce more as well as emit more light. By combining the analysis of metallicity with that of the brightness of galaxies it offers information on the masses of stars. The resulting model offers information on the history of star formation, and the application to a sample of 7,000 galaxies indicates that most stars formed in the first 4 billion years of the universe’s life.

Artist's concept of Pi Earth (Image courtesy NASA Ames/JPL-Caltech/T. Pyle, Christine Daniloff, MIT)

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An article published in “The Astronomical Journal” reports a study on the exoplanet K2-315b, nicknamed Pi Earth because its year lasts 3.14 Earth days, an approximation of the value of pi. A team of researchers from the SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) project, a network of ground-based telescopes, used them to confirm the planet’s existence by verifying data collected by NASA’s Kepler Space Telescope. Pi Earth is very close to its star so the temperature on its surface is very high even if the star is very small and relatively cold. Any life forms should be analogous to terrestrial extremophiles. It may be lifeless but it is an interesting candidate for studying its atmosphere.