ESO

Ancient Stardust Sheds Light on the First Stars

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This research was presented in a paper entitled “Dust in the Reionization Era: ALMA Observations of a z =8.38 Gravitationally-Lensed Galaxy”
by Laporte et al., to appear in 
The Astrophysical Journal Letters.

 
This artist’s impression shows what the very distant young galaxy A2744_YD4 might look like. Observations using ALMA have shown that this galaxy, seen when the Universe was just 4% of its current age, is rich in dust. Such dust was produced by an earlier generation of stars and these observations provide insights into the birth and explosive deaths of the very first stars in the Universe. Credit: ESO/M. Kornmesser
 
Astronomers have used ALMA to detect a huge mass of glowing stardust in a galaxy seen when the Universe was only four percent of its present age. This galaxy was observed shortly after its formation and is the most distant galaxy in which dust has been detected. This observation is also the most distant detection of oxygen in the Universe. These new results provide brand-new insights into the birth and explosive deaths of the very first stars.

An international team of astronomers, led by Nicolas Laporte of University College London, have used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe A2744_YD4, the youngest and most remote galaxy ever seen by ALMA. They were surprised to find that this youthful galaxy contained an abundance of interstellar dust — dust formed by the deaths of an earlier generation of stars.

Follow-up observations using the X-shooter instrument on ESO’s Very Large Telescope confirmed the enormous distance to A2744_YD4. The galaxy appears to us as it was when the Universe was only 600 million years old, during the period when the first stars and galaxies were forming [1].

 

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Ultracool Dwarf and the Seven Planets

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Dr. Paola Rebusco
MIT – Experimental Study Group
ESON USA
eson-usa@eso.org

This artist’s impression shows the view from the surface of one of the planets in the TRAPPIST-1 system. At least seven planets orbit this ultra cool dwarf star 40 light-years from Earth and they are all roughly the same size as the Earth. They are at the right distances from their star for liquid water to exist on the surfaces of several of them. This artist’s impression is based on the known physical parameters for the planets and stars seen, and uses a vast database of objects in the Universe. Credit: ESO/N. Bartmann/spaceengine.org

Astronomers using the TRAPPIST–South telescope at ESO’s La Silla Observatory, the Very Large Telescope (VLT) at Paranal and the NASA Spitzer Space Telescope, as well as other telescopes around the world [1], have now confirmed the existence of at least seven small planets orbiting the cool red dwarf star TRAPPIST-1 [2]. All the planets, labelled TRAPPIST-1b, c, d, e, f, g and h in order of increasing distance from their parent star, have sizes similar to Earth [3].

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(ESO) ALMA Starts Observing the Sun

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Roman Brajsa
Hvar Observatory, University of Zagreb
Croatia

Ivica Skokic
Astronomical Institute of the Czech Academy of Sciences
Ondrejov, Czech Republic

 

This image of the entire Sun was taken in the red visible light emitted by iron atoms in the Sun’s atmosphere. Light at this wavelength originates from the visible solar surface, the photosphere. A cooler, darker sunspot is clearly visible in the disc, and as a visual comparison is shown alongside the image from ALMA at a wavelength of 1.25 millimetres. The full-disc solar image was taken with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Credit: ALMA (ESO/NAOJ/NRAO), NASA.

 

Astronomers have harnessed the Atacama Large Millimeter/submillimeter Array (ALMA)s capabilities to image the millimetre-wavelength light emitted by the Sun’s chromosphere — the region that lies just above the photosphere, which forms the visible surface of the Sun. The solar campaign team, an international group of astronomers with members from Europe, North America and East Asia [1], produced the images as a demonstration of ALMA’s ability to study solar activity at longer wavelengths of light than are typically available to solar observatories on Earth.

Astronomers have studied the Sun and probed its dynamic surface and energetic atmosphere in many ways through the centuries. But, to achieve a fuller understanding, astronomers need to study it across the entire electromagnetic spectrum, including the millimetre and submillimetre portion that ALMA can observe.

 

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Hubble Finds Big Brother of Halley’s Comet – Ripped Apart By White Dwarf

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February 9, 2017
European Space Agency News Release 


Siyi Xu
European Southern Observatory
Garching bei München, Germany

Mathias Jäger
ESA/Hubble, Public Information Officer
Garching, Germany
 

This artist’s impression shows a massive, comet-like object falling towards a white dwarf. New observations with the NASA/ESA Hubble Space Telescope show evidence for a belt of comet-like bodies orbiting the white dwarf, similar to the Kuiper Belt in our own Solar System. The findings also suggest the presence of one or more unseen surviving planets around the white dwarf which may have perturbed the belt sufficiently to hurl icy objects into the burned-out star. Credit: NASA, ESA, and Z. Levy (STScI)

 

The international team of astronomers observed the white dwarf WD 1425+540, about 170 light-years from Earth in the constellation Boötes (the Herdsman) [1]. While studying the white dwarf’s atmosphere using both the NASA/ESA Hubble Space Telescope and the W. M. Keck Observatory the team found evidence that an object rather like a massive comet was falling onto the star, getting tidally disrupted while doing so.

The team determined that the object had a chemical composition similar to the famous Halley’s Comet in our own Solar System, but it was 100,000 times more massive and had twice the proportion of water as its local counterpart. Spectral analysis showed that the destroyed object was rich in the elements essential for life, including carbon, oxygen, sulphur and even nitrogen [2].

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