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annarita ruberto
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Stars Born in Winds from Supermassive Black Holes

ESO’s VLT spots brand-new type of star formation

A UK-led group of European astronomers used the MUSE and X-shooter instruments on the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile to study an ongoing collision between two galaxies, known collectively as IRAS F23128-5919, that lie around 600 million light-years from Earth.
The group observed the colossal winds of material — or outflows — that originate near the supermassive black hole at the heart of the pair’s southern galaxy, and have found the first clear evidence that stars are being born within them.

Such galactic outflows are driven by the huge energy output from the active and turbulent centres of galaxies. Supermassive black holes lurk in the cores of most galaxies, and when they gobble up matter they also heat the surrounding gas and expel it from the host galaxy in powerful, dense winds.

“Astronomers have thought for a while that conditions within these outflows could be right for star formation, but no one has seen it actually happening as it’s a very difficult observation,” comments team leader Roberto Maiolino from the University of Cambridge. “Our results are exciting because they show unambiguously that stars are being created inside these outflows.”

The group set out to study stars in the outflow directly, as well as the gas that surrounds them. By using two of the world-leading VLT spectroscopic instruments, MUSE and X-shooter, they could carry out a very detailed study of the properties of the emitted light to determine its source.

Radiation from young stars is known to cause nearby gas clouds to glow in a particular way. The extreme sensitivity of X-shooter allowed the team to rule out other possible causes of this illumination, including gas shocks or the active nucleus of the galaxy.

The group then made an unmistakable direct detection of an infant stellar population in the outflow. These stars are thought to be less than a few tens of millions of years old, and preliminary analysis suggests that they are hotter and brighter than stars formed in less extreme environments such as the galactic disc.

As further evidence, the astronomers also determined the motion and velocity of these stars. The light from most of the region’s stars indicates that they are travelling at very large velocities away from the galaxy centre — as would make sense for objects caught in a stream of fast-moving material.

Co-author Helen Russell (Institute of Astronomy, Cambridge, UK) expands: “The stars that form in the wind close to the galaxy centre might slow down and even start heading back inwards, but the stars that form further out in the flow experience less deceleration and can even fly off out of the galaxy altogether.”

The discovery provides new and exciting information that could better our understanding of some astrophysics, including how certain galaxies obtain their shapes; how intergalactic space becomes enriched with heavy elements; and even from where unexplained cosmic infrared background radiation may arise.

Maiolino is excited for the future: “If star formation is really occurring in most galactic outflows, as some theories predict, then this would provide a completely new scenario for our understanding of galaxy evolution.”

► Learn more>>

► This research was presented in a paper entitled “Star formation inside a galactic outflow” by Maiolino et al., to appear in the journal Nature on 27 March 2017.>>

Go to the ESO's PDF version, here>>

Image explanation: Artist’s impression of a galaxy forming stars within powerful outflows of material blasted out from supermassive black holes at its core. Results from ESO’s Very Large Telescope are the first confirmed observations of stars forming in this kind of extreme environment. The discovery has many consequences for understanding galaxy properties and evolution.
Credit: ESO/M. Kornmesser

Further reading

► Active galactic nucleus>>

► Supermassive black hole>>

► Astronomical spectroscopy>>

► Metallicity>>

► Cosmic infrared background>>

#Astrophysics, #SuperMassiveBlackHoles, #StarsFormation, #GalacticOutflow, #Research, #ESO, #VLT


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2MASS J0513-1403 as a Representative of the Smallest Possible Stars

2MASS J0523-1403 is a very-low-mass red dwarf about 40 light years from Earth in the southern constellation of Lepus. With a very faint visual magnitude of 21.05 and a low effective temperature of 2074 K, it is visible primarily in large telescopes sensitive to infrared light.

2MASS J0523-1403 was first observed as part of the Two Micron All-Sky Survey (2MASS).

2MASS J0523-1403 has a mass of <0.08 M☉ (solar mass) and a radius of 0.086 R☉ (solar radius). These values are currently the lowest known for a main sequence star.

Members of the RECONS (Research Consortium On Nearby Stars), group from Georgia State University, have recently identified 2MASS J0523-1403 as representative of the smallest possible stars.
2MASS J0523-1403 is just about at the lower bound between red dwarfs and brown dwarfs.

It’s 8.6% the size of the Sun, 61% the size of our nearest star Proxima Centauri, and 85.6% the size of Jupiter. Yes! This main-sequence star is smaller than Jupiter!

Let's see the reason.

For most of their lives, stars obey a relationship referred to as the main sequence, a relation between luminosity and temperature – which is also a relationship between luminosity and radius. Stars behave like balloons in the sense that adding material to the star causes its radius to increase: in a star the material is the element hydrogen, rather than air which is added to a balloon.
Brown dwarfs, on the other hand, are described by different physical laws (referred to as electron degeneracy pressure) than stars and have the opposite behavior. The inner layers of a brown dwarf work much like a spring mattress: adding additional weight on them causes them to shrink. Therefore brown dwarfs actually decrease in size with increasing mass.

In summary, 2MASS J0523-1403 small radius is at local minimums of the radius-luminosity and radius-temperature trends. This local minimum is predicted to occur at the hydrogen burning limit due to differences in the radius-mass relationships of stars and brown dwarfs. As previously said, brown dwarfs decrease in radius as mass increases due to their cores being supported by degeneracy pressure. As the mass increases an increasing fraction of the brown dwarf is degenerate causing the radius to shrink as mass increases. Add more mass yet and the density and temperature becomes sufficient to sustain hydrogen fusion, at which point it becomes a red dwarf. As a red dwarf, its radius will grow again as the mass increases.

That’s how 2MASS J0523-1403 can be smaller than a planet, despite being a main-sequence star.

Image: The red dwarf 2MASS J0523-1403 will still be shining long after most other stars have died.
Credit: Cerro Tololo Inter-American Observatory 0.9-meter Telescope. Sergio Dieterich

► Watch this video>>

Further reading and references

► NOAO/SOAR: Where do stars end and brown dwarfs begin?>>

► 2MASS J0523-1403>>

► How large is the smallest known star?>>

► A Star at the Edge of Eternity>>

#Astrophysics, #Universe, #RedDwarf, #Research, #2MASSJ0513_1403, #StarsEvolution


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Enceladus Creates Saturn's E Ring

The active moon Enceladus appears to be making Saturn's E ring.

An amazing picture showing the moon at work was taken late 2006 by the Saturn-orbiting Cassini spacecraft and is shown below.
Enceladus is the dark spot inside the bright flare, right near the center of Saturn's E ring.
Streams of ice and water vapor can be seen pouring off Enceladus into the E ring. The below bright image of the normally faint E-ring was made possible by aligning Cassini so that Saturn blocked the Sun. From that perspective, small ring particles reflect incoming sunlight more efficiently.

Enceladus is the sixth-largest moon of Saturn. It is about 500 kilometers (310 mi) in diameter, about a tenth of that of Saturn's largest moon, Titan. Enceladus is mostly covered by fresh, clean ice, making it one of the most reflective bodies of the solar system. Consequently, its surface temperature at noon only reaches −198 °C (−324 °F), far colder than a light-absorbing body would be.
Despite its small size, Enceladus has a wide range of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrains that formed as recently as 100 million years ago.

Saturn's E Ring is the second outermost ring and is extremely wide; it consists of many tiny (micron and sub-micron) particles of water ice with silicates, carbon dioxide and ammonia. The E Ring is distributed between the orbits of Mimas and Titan.
Unlike the other rings, it is composed of microscopic particles rather than macroscopic ice chunks. In 2005, the source of the E Ring's material was determined to be cryovolcanic plumes emanating from the "tiger stripes" of the south polar region of the moon Enceladus.
Unlike the main rings, the E Ring is more than 2000 kilometers thick and increases with its distance from Enceladus. Tendril-like structures observed within the E Ring can be related to the emissions of the most active south polar jets of Enceladus.


► Source>>

Further reading and references

► Ghostly Fingers of Enceladus>>

► Enceladus>>

► Saturn's E ring>>

► Cryovolcano>>

#SolarSystem, #Enceladus, #SaturnEring, #CassiniSpacecraft, #Saturn

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The LHCb Collaboration Announced the Discovery of a New System of Five Particles

The team notes that this observation improves our understanding of quantum theory in general and gives us new clues about the earliest moments of our universe.

In a paper released on 16 Mar 2017, the LHCb collaboration announced the discovery of a new system of five particles all in a single analysis. The exceptionality of this discovery is that observing five new states all at once is a rather unique event.

The particles were found to be excited states – a particle state that has a higher energy than the absolute minimum configuration (or ground state) – of a particle called "Omega-c-zero", Ωc0. This Ωc0 is a baryon, a particle with three quarks, containing two “strange” and one “charm” quark. Ωc0 decays via the strong force into another baryon, called "Xi-c-plus", Ξc+ (containing a “charm”, a “strange” and an “up” quark) and a kaon K-. Then the Ξc+ particle decays through the weak force in turn into a proton p, a kaon K- and a pion π+.

From the analysis of the trajectories and the energy left in the detector by all the particles in this final configuration, the LHCb collaboration could trace back the initial event – the decay of the Ωc0 – and its excited states.
These particle states are named, according to the standard convention, Ωc(3000)0, Ωc(3050)0, Ωc(3066)0, Ωc(3090)0 and Ωc(3119)0. The numbers indicate their masses in megaelectronvolts (MeV), as measured by LHCb.

Learn more>>

► Read the CERN announcement "16 March 2017: The magic of the Ωc baryon">>

► Read the scientific paper "Observation of five new narrow Ω0c states decaying to Ξ+cK−", published on arXiv>>

Image explanation: The image below shows the data (black dots) of the reconstructed mass distribution resulting from the combination of the Ξc+ and K- particles. The five particle states are the five narrow peaks standing out from the distribution of data. (Image: LHCb collaboration)

Further reading

► Omega baryons>>

► Strong force>>

► Weak force>>

► Kaon>>

► Pion>>

#Physics, #OmegaBaryons, #ElementaryParticles, #CERN, #LHCbCollaboration, #5ParticlesDiscovery, #Research

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Insulin Resistance May Lead to Faster Cognitive Decline

Executive function and memory are particularly vulnerable to the effects of insulin resistance, TAU researchers say

A new Tel Aviv University study published in the Journal of Alzheimer's Disease finds that insulin resistance, caused in part by obesity and physical inactivity, is also linked to a more rapid decline in cognitive performance. According to the research, both diabetic and non-diabetic subjects with insulin resistance experienced accelerated cognitive decline in executive function and memory.

The study was led jointly by Prof. David Tanne and Prof. Uri Goldbourt and conducted by Dr. Miri Lutski, all of TAU's Sackler School of Medicine.

"These are exciting findings because they may help to identify a group of individuals at increased risk of cognitive decline and dementia in older age,"says Prof. Tanne. "We know that insulin resistance can be prevented and treated by lifestyle changes and certain insulin-sensitizing drugs. Exercising, maintaining a balanced and healthy diet, and watching your weight will help you prevent insulin resistance and, as a result, protect your brain as you get older."

Learn more>>

► The study "Insulin Resistance and Future Cognitive Performance and Cognitive Decline in Elderly Patients with Cardiovascular Disease", published in the Journal of Alzheimer's Disease>>

► Image source>>

#Neuroscience, #Brain, #InsulinResistance, #Dementia, #CognitiveDecline, Research 

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CR7: a 'Chameleon' Galaxy and Its Persisting Puzzle

Cosmos Redshift 7 (also known as COSMOS Redshift 7, Galaxy Cosmos Redshift 7, Galaxy CR7 or CR7) is a high-redshift Lyman-alpha emitter galaxy (meaning CR7 is one of the oldest, most distant galaxies), in the constellation Sextans, about 12.9 billion light travel distance years from Earth, reported to contain the first stars (first generation; Population III)—formed soon after the Big Bang during the reionisation epoch (redshift, z ∼ 6−7), when the Universe was about 800 million years old—to have provided the chemical elements (like oxygen, nitrogen, carbon, calcium and iron) needed for the later formation of planets and life as it is known.

Discovery (in 2015)

Astronomers led by David Sobral from Lisbon and Leiden used the Very Large Telescope (VLT) at the European Southern Observatory—with help from the W. M. Keck Observatory, Subaru Telescope and the NASA/ESA Hubble Space Telescope— made the discovery in 2015. The research team included members of the University of California, Riverside, University of Geneva, University of Leiden and University of Lisbon.

The name of the galaxy (Cosmos Redshift 7 Galaxy) was inspired by Portuguese and Real Madrid footballer Cristiano Ronaldo, who is also popularly known as CR7.

A recent study (2017)

The peculiar emission properties of CR7 have been initially interpreted
with the presence of either a direct collapse black hole (DCBH) or a substantial mass of Pop III stars.
Instead, updated photometric observations by Bowler et al. (2016) seem to suggest that CR7 is a more standard system.

However, a more recent study- led by an Italian team of scientists from Department of Physics (Yale University, USA), Scuola Normale Superiore (Pisa, Italy), Cavendish Laboratory (University of Cambridge, UK), Kavli Institute for Cosmology (University of Cambridge, UK)- confirmed, with unprecedented accuracy, the original DCBH hypothesis is consistent also with the new data.

The study, published in the journal Monthly Notices of the Royal Astronomical Society, analysed a data set, collected through space telescopes Hubble (optical) and Spitzer (infrared). Italian team- led by Fabio Pacucci, a researcher at Yale- showed that the observational features of CR7 can be explained by the presence of a particular type of black hole, i.e. a direct collapse black hole (DCBH).
However, this study also describes how alternative explanations are possible.

Spectroscopic observations with JWST will be required to ultimately clarify the nature of CR7.

► Information come from a press release by Media INAF, the Italian National Institute of Astrophysics (in Italian)>>

The study on the nature of the Lyman Alpha Emitter CR7 at z=6.6 is described in this paper, published in the journal Monthly Notices of the Royal Astronomical Society>>

Read the preprint (16 February 2017) on arXiv>>

Image explanation: This artist’s impression shows CR7 a very distant galaxy discovered using ESO’s Very Large Telescope. It is by far the brightest galaxy yet found in the early universe.
Image Credit: ESO/M. KORNMESSER.

Further reading

► Astronomers Find Best Observational Evidence of First-generation Stars in the Universe (June 2015)>>

► CR7 is not alone: a team of super bright galaxies in the early Universe (June 2016)>>

► Cosmos Redshift 7>>

#Astrophysics, #BlackHolePhysics, #Galaxies, #Photometry, #Cosmology, #DarkAges, #Reionization, #FirstStars, #EarlyUniverse, #Research

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NGC 3621: A Bulgeless Galaxy with Three Central Black Holes

This image shows a truly remarkable field spiral galaxy, known as NGC 3621. To begin with, it is a pure-disc galaxy. Like other spirals, it has a flat disc permeated by dark lanes of material and with prominent spiral arms where young stars are forming in clusters (the blue dots seen in the image).
But while most spiral galaxies have a central bulge — a large group of old stars packed in a compact, spheroidal region — NGC 3621 doesn’t.
In this image, it is clear that there is simply a brightening to the centre, but no actual bulge like the one in NGC 6744 (eso1118), for example.

NGC 3621 is also interesting as it is believed to have an active supermassive black hole at its centre that is engulfing matter and producing radiation.
This is somewhat unusual because most of these so-called active galactic nuclei exist in galaxies with prominent bulges. In this particular case, the supermassive black hole is thought to have a relatively small mass, of around 20 000 times that of the Sun.

Another interesting feature is that there are also thought to be two smaller black holes, with masses of a few thousand times that of the Sun, near the nucleus of the galaxy. Therefore, NGC 3621 is an extremely interesting object which, despite not having a central bulge, has a system of three black holes in its central region.

This galaxy is located about 22 Mly away, in the constellation of Hydra (The Sea Snake), and can be seen with a moderate-sized telescope. It shines with a luminosity equal to 13 billion times that of the Sun.
Some of its brighter stars have been used as standard candles to establish important estimates of extragalactic distances and the scale of the Universe.

Image explanation: this beautiful image of NGC 3621, is a composite of space- and ground-based telescope data. It traces the loose spiral arms far from the galaxy's brighter central regions for some 100,000 light-years. Spiky foreground stars in our own Milky Way Galaxy and even more distant background galaxies are scattered across the colorful skyscape.
Image Credit & Copyright: Processing - Robert Gendler, Roberto Colombari
Data - Hubble Legacy Archive, European Southern Observatory, et al.

Further reading and references

► NGC 3621: Far Beyond the Local Group >>

► A galaxy full of surprises>>

► NGC 3621>>

► Field galaxy>>

► Spiral galaxy>>

#Universe, #Galaxies, #Space, #NGC3621, #FieldSpiralGalaxy

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Animated Photo

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Celestial Cycles

► Creation from Charlie Deck>>

Animation inspired by an image that pertains to epicycles>>

Further reading

► Deferent and epicycle>>

► Eccentrics, Deferents, Epicycles, and Equants>>

#gif, #processing, #design, #geometry, #perfectloop, #math
Animated Photo

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Radiation from Nearby Galaxies Helped Fuel First Monster Black Holes

The appearance of supermassive black holes at the dawn of the universe has puzzled astronomers since their discovery more than a decade ago.
A supermassive black hole is thought to form over billions of years, but more than two dozen of these behemoths have been sighted within 800 million years of the Big Bang 13.8 billion years ago.

In a new study in the journal Nature Astronomy, a team of researchers from Dublin City University, Columbia University, Georgia Tech, and the University of Helsinki, add evidence to one theory of how these ancient black holes, about a billion times heavier than our sun, may have formed and quickly put on weight.

In computer simulations, the researchers show that a black hole can rapidly grow at the center of its host galaxy if a nearby galaxy emits enough radiation to switch off its capacity to form stars. Thus disabled, the host galaxy grows until its eventual collapse, forming a black hole that feeds on the remaining gas, and later, dust, dying stars, and possibly other black holes, to become super gigantic.

“The collapse of the galaxy and the formation of a million-solar-mass black hole takes 100,000 years — a blip in cosmic time,” says study co-author Zoltan Haiman, an astronomy professor at Columbia University. “A few hundred-million years later, it has grown into a billion-solar-mass supermassive black hole. This is much faster than we expected.”

In the early universe, stars and galaxies formed as molecular hydrogen cooled and deflated a primordial plasma of hydrogen and helium. This environment would have limited black holes from growing very big as molecular hydrogen turned gas into stars far enough away to escape the black holes’ gravitational pull. Astronomers have come up with several ways that supermassive black holes might have overcome this barrier.

Learn more>>

► The study "Rapid formation of massive black holes in close proximity to embryonic protogalaxies", published in the journal Nature Astronomy>>

► Read the preprint on arXiv>>

Image explanation: The massive black hole shown at left in this drawing is able to rapidly grow as intense radiation from a galaxy nearby shuts down star-formation in its host galaxy.
Illustration Courtesy of John Wise, Georgia Tech

#Astrophysics, #MassiveBlackHoles, #Protogalaxies, #StarFormation, #EarlyUniverse, #Research
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