June 2020

Proxima Centauri seen from Earth and the New Horizons space probe

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NASA has released images obtained by its New Horizons space probe during the interstellar parallax experiment conducted on April 22 / 23, 2020. The LORRI camera was aimed at Proxima Centauri and Wolf 359, two of the stars closest to the system solar, obtaining images that show how they appear in different positions from the ones we see from Earth. It’s an application of the parallax phenomenon with the apparent movement of the two stars caused by the fact that New Horizons is about 7 billion kilometers from Earth. The combination of images captured by New Horizons and an instrument on Earth shows the parallax effect, which in the future could help interstellar navigation instruments like sailors have been using the positions of stars to navigate the seas of Earth.

The disaggregation (top row) and linear fractures (bottom row) in rocks on asteroid Bennu

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An article published in the journal “Nature Communications” reports the evidence of thermal fractures on asteroid Bennu caused by the temperature difference between day and night. A team of researchers led by Jamie Molaro of the Planetary Science Institute in Tucson, Arizona, examined images of Bennu’s surface captured by NASA’s OSIRIS-REx space probe, and found examples of this phenomenon. It’s the first detection of this phenomenon on an object without an atmosphere, and this offers new information to understand the evolution of Bennu and in general of asteroids over time. That includes the progressive disaggregation of rocks through the particular effect of thermal fracturing called exfoliation.

Some stars and planets situations

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An article published in the journal “Astronomy & Astrophysics” reports the discovery of an exoplanet candidate with a very high probability of existence, a super-Earth designated as KOI-456.04 whose estimated year is slightly longer than the Earth’s that orbits Kepler-160, a Sun-like star. A team of researchers led by René Heller of the Max Planck Institute for Solar System Research in Göttingen, Germany, analyzed old data accumulated by the Kepler space telescope using a new method based on the detailed physical model of the stellar brightness variation instead of the classic one based on the search for the tiny drops in brightness that occur when the planet passes between the star and the telescope. The analysis also led to the discovery of another exoplanet candidate designated as Kepler-160 d.

Artist's concept of W1200-7845 with its protoplanetary disk (Image NASA/William Pendrill)

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At the 236th Meeting of the American Astronomical Society (AAS) held in recent days, on this occasion virtually and not in a physical place due to the Covid-19 pandemic, the discovery of the youngest brown dwarf of our cosmic neighborhood was announced. Named W1200-7845, it’s so young that it has a protoplanetary disk, a really interesting discovery because it will allow to study a possible planetary formation around an object that can be considered a failed star. This result came thanks to the Disk Detective program, which allows citizen scientists to examine astronomical images captured by NASA’s WISE space telescope, looking for protoplanetary disks. Its discovery allowed to conduct follow-up observations to study its evolution.

A section of the three-dimensional map of the galaxies of the Sloan Digital Sky Survey used for the analysis

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An article published in the journal “Physical Review Letters” reports a new estimate of the expansion of the universe based on the large cosmic structures formed by galaxies. A team of researchers led by Dr. Seshadri Nadathur of the British University of Portsmouth’s Institute of Cosmology and Gravitation (ICG) used data about over one million galaxies and quasars collected over a decade by the Sloan Digital Sky Survey to create an analysis that provided a measure of the effects of the mysterious dark energy that’s accelerating the expansion of the universe. Adding a new method of its calculation doesn’t necessarily lead to the right value, but can help understand why other methods provide incompatible results and where we might need to expand our knowledge of physics to obtain the right value.