On this day in 1994, Jupiter continues to be pummeled by Comet Shoemaker-Levy 9 as four more comet fragments impact the planet.

Astronomers measure detailed chemical abundances of 158 stars in a nearby dwarf galaxy
https://phys.org/news/2017-07-astronomers-chemical-abundances-stars-nearby.html

An international team of astronomers has performed detailed measurements of the chemical composition of 158 red giant stars in the nearby Sagittarius dwarf
galaxy. The study, presented in a paper published July 11 on arXiv.org, is so far the largest and most chemically extensive high-resolution survey of this galaxy.

Discovered in 1994, Sagittarius is a nearby, massive, elliptical loop-shaped satellite galaxy of the Milky Way. The dwarf is currently merging with our galaxy,
resulting in massive tidal tails that can be found in the Galactic halo. Therefore, detailed studies of Sagittarius could clarify the formation of Milky Way's halo.
Due to its proximity (about 88,000 light years away), the stars in the core of this dwarf galaxy are excellent targets for high-resolution spectroscopy observations
using ground-based telescopes.

So a team of researchers led by Sten Hasselquist of the New Mexico State University recently conducted detailed spectroscopic observations of Sagittarius as part of
the Apache Point Observatory Galactic Evolution Experiment, or APOGEE. The main goal of this survey is to study over 100,000 red giant stars across the full range of
the galactic bulge, bar, disk, and halo. APOGEE makes use of a high-resolution near-infrared spectrograph connected to the Sloan Foundation 2.5m Telescope at Apache
Point Observatory in New Mexico in order to penetrate the dust that obscures significant fractions of the disk and bulge of our galaxy.

Hasselquist and colleagues has used APOGEE's spectrograph to estimate chemical composition of a large group of stars in Sagittarius. They managed to measure chemical
abundances for the 16 elements, namely carbon (C), nitrogen (N), oxygen (O), sodium (Na), magnesium (Mg), aluminium (Al), silicon (Si), phosphorus (P), potassium (K),
calcium (Ca), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co) and nickel (Ni).

"The Apache Point Observatory Galactic Evolution Experiment provides the opportunity to measure elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn,
Fe, Co, and Ni in vast numbers of stars. We analyze the chemical abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy
(Sgr)," the researchers wrote in the paper.

Is Dark Matter Real?
https://www.livescience.com/59814-is-dark-matter-real.html

Many science-savvy people take it for granted that the universe is made not only of Carl Sagan's oft-quoted "billions and billions" of galaxies, but also a vast
amount of an invisible substance called dark matter. This odd matter is thought to be a new kind of subatomic particle that doesn't interact via electromagnetism,
nor the strong and weak nuclear forces. Dark matter is also supposed to be five times more prevalent in the universe than the ordinary matter of atoms.

However, the reality is that dark matter's existence has not yet been proved. Dark matter is still a hypothesis, albeit a rather well-supported one. Any scientific
theory has to make predictions, and if it's right, then the measurements you do should line up with the predictions. The same goes for dark matter. For instance,
dark matter theories make predictions for how fast galaxies are rotating. But, until now, measurements made of the detailed dark matter distribution at the center
of low mass galaxies didn't line up with those predictions.

A recent calculation has changed that. The calculation helps resolve the conundrum of the Tully-Fisher relation, which compares the visible, or ordinary, matter of a
galaxy to its rotational velocity. In very simplified terms, scientists have found that the more massive (and therefore brighter) a spiral galaxy is, the faster it spins.

Podcast: On July 10, researchers using NASA’s Stratospheric Observatory for Infrared Astronomy, or SOFIA, will attempt to study
the environment around a distant Kuiper Belt Object, 2014 MU69, which is the next flyby target for NASA’s New Horizons spacecraft.

http://pluto.jhuapl.edu/common/content/videos/podcasts/KBO%20podcast%203%20v2_640x360.mp4

Astronomers discover one of the brightest galaxies known
https://phys.org/news/2017-07-astronomers-brightest-galaxies.html

Thanks to an amplified image produced by a gravitational lens, and the Gran Telescopio CANARIAS a team of scientists
from the Polytechnic University of Cartagena and the Instituto de Astrofísica de Canarias have discovered one of the
brightest galaxies known from the epoch when the universe had 20 percent of its present age.

Using this effect, a team of scientists from the Instituto de Astrofisica de Canarias (IAC) led by researcher Anastasio
Díaz-Sánches of the Polytechnic University of Cartagena (UPT) has discovered a very distant galaxy, some 10 thousand
million light years away, about a thousand times brighter than the Milky Way. It is the brightest of the submillimetre
galaxies, called this because of their very strong emissionin the far infrared. To measure it they used the Gran
Telescopio Canarias (GTC) at the Roque de los Muchachos Observatory (Garafía, La Palma).

This is what it would take to kill all life on Earth | Science | AAAS
http://www.sciencemag.org/news/2017/07/what-it-would-take-kill-all-life-earth

A giant asteroid crashing into our planet would instantly kill off millions of animals. But the aftermath of such an impact would be even more disastrous:
Tsunamis, earthquakes, and vast clouds of dust blocking out the sun would lead to crop failure and mass extinction. Sixty-five million years ago, just such
an event killed off 75% of species on Earth. But to really wipe life off the planet, it would take an astrophysical event so powerful that Earth’s oceans
would literally boil away, according to a new study. The heat and cosmic radiation would make Earth inhospitable even to tardigrades, among the hardiest
organisms ever discovered.

“They’ve taken a grand question—how resilient is life?—and turned [it] into a well-posed calculation, by focusing on the energy required to boil Earth’s
oceans,” says Joshua Winn, an exoplanets expert at Princeton University, who was not involved in the study. “It’s an awful lot of energy.”

Researchers first calculated the amount of energy it would take to bring all Earth’s water above 100°C: 6 x 1022 joules, about a hundred times more than
total annual energy consumption by humans, or a trillion times the energy needed for the space shuttle to lift off. Translated into cataclysms, it would
take the energy given off by the impact of an asteroid the size of Vesta or Pallas, among the solar system’s biggest, they report today in Scientific
Reports. Other options: exploding stars known as supernovae or gamma ray bursts, highly energetic explosions in outer space.

Study finds our Sun is like other stars, resolving mystery
https://phys.org/news/2017-07-sun-stars-mystery.html

Our Sun is much like other stars, and not an anomaly because of its magnetic poles that flip every 11 years, scientists said Thursday.

The report in the journal Science aims to lay to rest the controversy over whether our solar system's star is cyclic, like other nearby,
solar-type stars. "We have shed light on a fundamental mechanism which determines the length of these cycles, which helps us understand
the cycle itself over the long-term," lead author Antoine Strugarek, a researcher at the University of Montreal, told AFP.

VIRGO: NASA Video Soars over Pluto’s Majestic Mountains and Icy Plains
https://www.nasa.gov/feature/nasa-video-soars-over-pluto-s-majestic-mountains-and-icy-plains

New Horizons Flyover of Pluto
https://www.youtube.com/watch?v=g1fPhhTT2Oo


New Horizons Flyover of Charon
https://www.youtube.com/watch?v=f0Q7O7TZ7Ks

New Horizons Unveils New Maps of Pluto, Charon on Flyby Anniversary
https://www.nasa.gov/feature/new-horizons-unveils-new-maps-of-pluto-charon-on-flyby-anniversary

On July 14, 2015, NASA’s New Horizons spacecraft made its historic flight through the Pluto system – providing the first close-up images of Pluto
and its moons and collecting other data that has transformed our understanding of these mysterious worlds on the solar system’s outer frontier.

Scientists are still analyzing and uncovering data that New Horizons recorded and sent home after the encounter. On the two-year anniversary of
the flyby, the team is unveiling a set of detailed, high-quality global maps of Pluto and its largest moon, Charon.

Complex Gas Motion in the Centre of the Milky Way - Communications and Marketing - Heidelberg University
http://www.uni-heidelberg.de/presse/news2017/pm20170713_milchstrasse_en.html

How does the gas in the centre of the Milky Way behave? Researchers from Heidelberg University, in collaboration with colleagues
from the University of Oxford, recently investigated the motion of gas clouds in a comprehensive computer simulation. The new model
finally makes it possible to conclusively explain this complex gas motion. Astrophysicists Dr Mattia C. Sormani (Heidelberg) and Matthew
Ridley (Oxford) conducted the research, on Heidelberg’s part, at the Collaborative Research Centre "The Milky Way System" (CRC 881).

Take a 360° spin through the heart of the sun | Science | AAAS
http://www.sciencemag.org/news/2017/07/take-360-spin-through-heart-sun

360 Video: Inside the heart of a star's magnetic field.
https://www.youtube.com/watch?v=eSoyqFcK22k

Researchers describe one of the most massive large-scale structures in the universe
https://phys.org/news/2017-07-massive-large-scale-universe.html

A team of astronomers from the Inter University Centre for Astronomy & Astrophysics (IUCAA), and Indian Institute of Science Education and Research (IISER),
both in Pune, India, and members of two other Indian universities, have identified a previously unknown, extremely large supercluster of galaxies located in
the direction of constellation Pisces. This is one of the largest known structures in the nearby Universe, and is at a distance of 4,000 million (400 crore)
light-years away from us.

This novel discovery is being published in the latest issue of The Astrophysical Journal, the premier research journal of the American Astronomical Society.

Large-scale structures in the Universe are found to be hierarchically assembled, with galaxies, together with associated gas, and dark matter, being clumped
in clusters, which are organized with other clusters, smaller groups, filaments, sheets and large empty regions ("voids") in a pattern called the "Cosmic web"
which spans the observable Universe.

Superclusters are the largest coherent structures in the Cosmic Web. A Supercluster is a chain of galaxies and galaxy clusters, bound by gravity, often
stretching to several hundred times the size of clusters of galaxies, consisting of tens of thousands of galaxies. This newly-discovered 'Saraswati'
supercluster, for instance, extends over a scale of 600 million light-years and may contain the mass equivalent of over 20 million billion suns.