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Posts tagged "astrophysics"

afro-dominicano:

Hubble Helps Astronomers Find Smallest Known Galaxy With Supermassive Black Hole

Astronomers using the NASA/ESA Hubble Space Telescope have found a monster lurking in a very unlikely place.

New observations of the ultracompact dwarf galaxy M60-UCD1 have revealed a supermassive black hole at its heart, making this tiny galaxy the smallest ever found to host a supermassive black hole.

This suggests that there may be many more supermassive black holes that we have missed, and tells us more about the formation of these incredibly dense galaxies. The results will be published in the journal Nature on 18 September 2014.

Lying about 50 million light-years away, M60-UCD1 is a tiny galaxy with a diameter of 300 light-years — just 1/500th of the diameter of the Milky Way. Despite its size it is pretty crowded, containing some 140 million stars. While this is characteristic of an ultracompact dwarf galaxy (UCD) like M60-UCD1, this particular UCD happens to be the densest ever seen.

Despite their huge numbers of stars, UCDs always seem to be heavier than they should be. Now, an international team of astronomers has made a new discovery that may explain why — at the heart of M60-UCD1 lurks a supermassive black hole with the mass of 20 million Suns.

"We’ve known for some time that many UCDs are a bit overweight. They just appear to be too heavy for the luminosity of their stars," says co-author Steffen Mieske of the European Southern Observatory in Chile. "We had already published a study that suggested this additional weight could come from the presence of supermassive black holes, but it was only a theory. Now, by studying the movement of the stars within M60-UCD1, we have detected the effects of such a black hole at its centre. This is a very exciting result and we want to know how many more UCDs may harbour such extremely massive objects."

The supermassive black hole at the centre of M60-UCD1 makes up a huge 15 percent of the galaxy’s total mass, and weighs five times that of the black hole at the centre of the Milky Way. “That is pretty amazing, given that the Milky Way is 500 times larger and more than 1000 times heavier than M60-UCD1,” explains Anil Seth of the University of Utah, USA, lead author of the international study. “In fact, even though the black hole at the centre of our Milky Way galaxy has the mass of 4 million Suns it is still less than 0.01 percent of the Milky Way’s total mass, which makes you realise how significant M60-UCD1’s black hole really is.”

afro-dominicano:

Mapping the Light of the Cosmos

Figuring out what the structure of the universe is surprisingly hard. Most of the matter that makes up the cosmos is totally dark, and much of what is left is in tiny, dim galaxies that are virtually impossible to detect.

Image: The first image above shows one possible scenario for the distribution of light in the cosmos. Credit: Andrew Pontzen/Fabio Governato

This image shows a computer simulation of one possible scenario for the large-scale distribution of light sources in the universe. The details of how light (and hence galaxies and quasars) is distributed through the cosmos is still not a settled question – in particular, the relative contributions of (faint but numerous) galaxies and (bright but rare) quasars is unknown.

(New research from UCL cosmologists published last week shows how we should be able to find out soon.)

However, astronomers know that on the largest scales, the universe is structured as a vast web made up of filaments and clusters of galaxies, gas and dark matter separated by huge, dark voids. Observational astronomy is making strides forward in mapping out these structures in gas and light, but the smallest galaxies – less than a pixel across in the image above – might never be seen directly because they are simply too faint.

A Hubble image of a nearby faint dwarf galaxy (bottom image) shows the challenge involved in observing these objects even when they are in our galaxy’s vicinity.

These computer models are one way of trying to extrapolate from what we know to what is really there. New research from UCL now shows how we can also use future observations of gas to find out more about this elusive population of tiny galaxies.

This simulated image shows the distribution of light in an area of space over 50 million light-years across. The simulation was created by Andrew Pontzen of UCL and Fabio Governato of the University of Washington.

afro-dominicano:

First Water Ice Clouds Found Beyond Our Solar System

For the first time, astronomers have detected water ice clouds, like the ones that shroud Earth, around a dim celestial body outside of our solar system.

Image: Astronomers have detected traces of water ice clouds in the atmosphere of the brown dwarf WISE 0855, a misfit failed star about 7.2 light-years from Earth. The discovery is the first time water ice clouds have been found beyond the solar system, scientists say Credit: Rob Gizis (CUNY BMCC) via Carnegie Institution/YouTube

Scientists discovered evidence of the alien water ice clouds in infrared images of a newly discovered brown dwarf that’s as cold as the North Pole.

"Ice clouds are predicted to be very important in the atmospheres of planets beyond our solar system, but they’ve never been observed outside of it before now," study leader Jacqueline Faherty, who is a fellow at the Carnegie Institution for Science in Washington, D.C., said in a statement.

Ice water has been found around gas giants in our solar system. NASA’s Cassini spacecraft recently detected water ice crystals on Saturn that had been churned up from deep inside the ringed planet’s thick atmosphere during a huge storm. Water ice clouds are also hidden underneath Jupiter’s stormy ammonia ice clouds.

Now, scientists found faint signatures of such clouds around the brown dwarf WISE J085510.83-071442.5, or W0855 for short. The object is the coldest brown dwarf ever observed by scientists. It lurks 7.2 light-years away from Earth and was first seen by NASA’s Wide-Field Infrared Explorer.

afro-dominicano:

NGC 6589-90

by Robert Gendler

This rich nebula complex is located near the center of the galaxy where dust is ubiquitous and often partially obscures the view at visible wavelengths.

The two bright blue clouds are NGC 6589 and NGC 6590. The clouds represent scattered starlight from two imbedded young blue stars. The two bright stars are part of a loose cluster known as NGC 6595. The diffuse magenta cloud is a complex HII region which absorbs the energy from the nearby bright stars and releases it in the visible red light of excited hydrogen.

The HII clouds are known as IC 1283, IC 1284 and IC 4700. This region of our galaxy is rich with dust clouds and young stars which together produce the stunning reflection nebulae we see in the image.[**]

X-ray image of the SNR (Supernova Remnant): Puppis A by Gloria Dubner

Puppis A is a supernova remnant (SNR) about 10 light-years in diameter. The supernova ‘occurred’ (i.e. would have been seen on earth) approximately 3700 years ago. Although it overlaps the Vela Supernova Remnant, it is four times more distant.[**]

New Galactic Supercluster Map Shows Milky Way’s ‘Heavenly’ Home

A new cosmic map is giving scientists an unprecedented look at the boundaries for the giant supercluster that is home to Earth’s own Milky Way galaxy and many others. Scientists even have a name for the colossal galactic group: Laniakea, Hawaiian for “immeasurable heaven.”

Image 1: Scientists have created the first map of a colossal supercluster of galaxies known as Laniakea, the home of Earth’s Milky Way galaxy and many other. This computer simulation, a still from a Nature journal video, depicts the giant supercluster, with the Milky Way’s location shown as a red dot. Credit: [Nature Video](https://www.youtube.com/watch?v=rENyyRwxpHo)

Image 2: This computer-generated depiction of the Laniakea Supercluster of galaxies, which includes the Milky Way galaxy containing Earth’s solar system, shows a view of the supercluster as seen from the supergalactic equatorial plane. Credit: SDvision interactive visualization software by DP at CEA/Saclay, France

The scientists responsible for the new 3D map suggest that the newfound Laniakea supercluster of galaxies may even be part of a still-larger structure they have not fully defined yet.

"We live in something called ‘the cosmic web,’ where galaxies are connected in tendrils separated by giant voids," said lead study author Brent Tully, an astronomer at the University of Hawaii at Honolulu.

Galactic structures in space

Galaxies are not spread randomly throughout the universe. Instead, they clump in groups, such as the one Earth is in, the Local Group, which contains dozens of galaxies. In turn, these groups are part of massive clusters made up of hundreds of galaxies, all interconnected in a web of filaments in which galaxies are strung like pearls. The colossal structures known as superclusters form at the intersections of filaments.

The giant structures making up the universe often have unclear boundaries. To better define these structures, astronomers examined Cosmicflows-2, the largest-ever catalog of the motions of galaxies, reasoning that each galaxy belongs to the structure whose gravity is making it flow toward.

"We have a new way of defining large-scale structures from the velocities of galaxies rather than just looking at their distribution in the sky," Tully said.

(via afro-dominicano)

Traces of One of Universe’s First Stars Detected

An ancient star in the halo surrounding the Milky Way galaxy appears to contain traces of material released by the death of one of the universe’s first stars, a new study reports.

The chemical signature of the ancient star suggests that it incorporated material blasted into space by a supernova explosion that marked the death of a huge star in the early universe — one that may have been 200 times more massive than the sun.

"The impact of very-massive stars and their explosions on subsequent star formation and galaxy formation should be significant," lead author Wako Aoki, of the National Astronomical Observatory of Japan, told Space.com by email.

(via afro-dominicano)

afro-dominicano:

World’s Biggest Laser Blasts Diamond to Simulate Planet Cores

The biggest laser in the world was used to crush a diamond, offering insights into how the hardest known material behaves when it is exposed to extremely high pressures. The experiment could also reveal new clues about what happens at the cores of giant planets, where conditions of intense atmospheric pressures exist.

Researchers at the Lawrence Livermore National Laboratory in Livermore, California, led by physicist Raymond Smith, blasted a sliver of diamond with a laser beam at a pressure of 725 million pounds per square inch (51 million kilograms per square centimeter). This is the kind of pressure found near the core of giant planets, such as Jupiter or huge, rocky bodies known as “super-Earths.”

The entire experiment took only 25 billionths of a second. The researchers fired 176 laser beams at a small cylinder of gold, called a hohlraum, with a tiny chip of synthetic diamond embedded in it. When the laser beams hit the cylinder, the energy was converted to X-rays. The hohlraum was vaporized, and in the process, the diamond was exposed to pressures tens of millions of times Earth’s atmospheric pressure.

Theoretical calculations predicted that such high pressures should cause a diamond to change its crystal structure. One way to test if this is true is to measure the speed of sound waves in a material. If this speed changes abruptly as the pressure goes up, then the diamond structure has rearranged itself.

But that didn’t happen — the velocity of sound waves changed smoothly.

"If there was a phase transformation you’d expect a discontinuity," Smith said.

The rate of change in the diamond’s density also didn’t match up with earlier theoretical models. Materials typically become denser at high pressures, and diamond is no exception. But how fast its density changed was a surprise, the researchers said.

The experiment was a breakthrough, in that instead of smacking the diamond with high pressure in a stepwise fashion, such as hitting it with successively heavier hammers, the researchers were able to boost the pressure smoothly. This enabled them to crush the diamond and expose it to intense pressure without the substance becoming too hot and melting. (Diamonds can and do melt at sufficiently high temperatures).

Since diamonds are made of carbon, understanding how this material behaves at high pressures can be important in the study of planets around other stars, said Nikku (Madhu) Madhusudhan, a professor of astrophysics at the University of Cambridge.

spaceplasma:

Spectroscopy and the Birth of Astrophysics

The 3D animation (above) depicts how the light of a distant star is studied by astronomers. The spectrum of the light provides vital information about the composition and history of stars. Now, let’s look into the history of stellar spectroscopy.

In 1802, William Wollaston noted that the spectrum of sunlight did not appear to be a continuous band of colours, but rather had a series of dark lines superimposed on it. Wollaston attributed the lines to natural boundaries between colours. Joseph Fraunhofer made a more careful set of observations of the solar spectrum in 1814 and found some 600 dark lines, and he specifically measured the wavelength of 324 of them. Many of the Fraunhofer lines in the solar spectrum retain the notations he created to designate them. In 1864, Sir William Huggins matched some of these dark lines in spectra from other stars with terrestrial substances, demonstrating that stars are made of the same materials of everyday material rather than exotic substances. This paved the way for modern spectroscopy.

Since even before the discovery of spectra, scientists had tried to find ways to categorize stars. By observing spectra, astronomers realized that large numbers of stars exhibit a small number of distinct patterns in their spectral lines. Classification by spectral features quickly proved to be a powerful tool for understanding stars.

The current spectral classification scheme was developed at Harvard Observatory in the early 20th century. Work was begun by Henry Draper who photographed the first spectrum of Vega in 1872. After his death, his wife donated the equipment and a sum of money to the Observatory to continue his work. The bulk of the classification work was done by Annie Jump Cannon from 1918 to 1924. The original scheme used capital letters running alphabetically, but subsequent revisions have reduced this as stellar evolution and typing has become better understood.

While the differences in spectra might seem to indicate different chemical compositions, in almost all instances, it actually reflects different surface temperatures. With some exceptions (e.g. the R, N, and S stellar types), material on the surface of stars is “primitive”: there is no significant chemical or nuclear processing of the gaseous outer envelope of a star once it has formed. Fusion at the core of the star results in fundamental compositional changes, but material does not generally mix between the visible surface of the star and its core. Ordered from highest temperature to lowest, the seven main stellar types are O, B, A, F, G, K, and M. Astronomers use one of several mnemonics to remember the order of the classification scheme. O, B, and A type stars are often referred to as early spectral types, while cool stars (G, K, and M) are known as late type stars.

Scientists assumed that the spectral classes represented a sequence of decreasing surface temperatures of the stars, but no one was able to demonstrate this quantitatively. Cecilia Payne, who studied the new science of quantum physics, knew that the pattern of features in the spectrum of any atom was determined by the configuration of its electrons. She showed that Cannon’s ordering of the stellar spectral classes was indeed a sequence of decreasing temperatures and she was able to calculate the temperatures.

  • More information: here

Credit: ESO, Jesse S. Allen

afro-dominicano:

Markarian’s Chain: M84, M86, M87 in Virgo byMakis Palaiologou, Stefan Binnewies and Josef Pöpsel

Markarian’s Chain is a stretch of galaxies that forms part of the Virgo Cluster. It is called a chain because, when viewed from Earth, the galaxies lie along a smoothly curved line. It was named after the Armenian astrophysicist, B. E.

Ancient Asteroid Destroyer Finally Found, And It’s a New Kind of Meteorite

For 50 years, scientists have wondered what annihilated the ancestor of L-chondrites, the roof-smashing, head-bonking meteorites that frequently pummel Earth.

Image: Credit:

Now, a new kind of meteorite discovered in a southern Sweden limestone quarry may finally solve the mystery, scientists report. The strange new rock may be the missing “other half” from one of the biggest interstellar collisions in a billion years.

"Something we didn’t really know about before was flying around and crashed into the L-chondrites," said study co-author Gary Huss of the University of Hawaii at Manoa.

The space rock is a 470-million-year-old fossil meteorite first spotted three years ago by workers at Sweden’s Thorsberg quarry, where stonecutters have an expert eye for extraterrestrial objects. Quarriers have plucked 101 fossil meteorites from the pit’s ancient pink limestone in the last two decades.

Mysterious find

Geochemically, the meteorite falls into a class called the primitive achondrites, and most resembles a rare group of achondrites called the winonaites. But small differences in certain elements in its chromite grains set the mysterious object apart from the winonaites, and its texture and exposure age distinguish the new meteorite from the other 49,000 or so meteorites found so far on Earth.

"It’s a very, very strange and unusual find," Schmitz told Live Science’s Our Amazing Planet.

The new meteorite was recently reported online in the journal Earth and Planetary Science Letters, and the study will appear in the journal’s Aug. 15 print edition.

(via afro-dominicano)

afro-dominicano:

'Cosmos' Finale Brings a (Big) Bang of Wonder

For astrophysicist Neil deGrasse Tyson, the scientific exploration of our universe is one amazing voyage, and so too has been his run on the new “Cosmos.”

As host of Fox’s science-themed “Cosmos: A Spacetime Odyssey,” Tyson has carried readers back and forth through time, revisited scientists during pivotal discoveries and introduced a new generation to the wonder of space and science. The show debuted in March and airs its 13th and final episode tonight (June 8).

"We end on a note where yes, this is a journey. It’s a look at how far it’s come, look at how much further it can go," Tyson told reporters Friday. “It’s our solar curiosity, if you will, that will keep that pumped. Without it, I don’t know that the country or the world or culture or civilization can go anywhere.”

"Cosmos: A Spacetime Odyssey" is a 21st-century reboot of the iconic 1980 PBS series "Cosmos: A Personal Journey" hosted by the famed astronomer popularizer of science Carl Sagan, who died in 1996. Like that original series, the new show is led by Ann Druyan, Sagan’s widow and longtime partner, who serves as co-writer and executive producer.

But there has been one major difference. This new “Cosmos” has been big. Unlike the 1980 series, which aired on public television, the new “Cosmos” aired Sunday nights on Fox, then again on Monday nights on the National Geographic Channel. The series was beamed out to 181 countries and launched with a tie-in app for mobile devices and well as a vigorous social media campaign.

"I have a feeling that the reaction to the series has exceeded my wildest fantasies," Druyan told Space.com Friday during a conference call. She added that she was stunned last Sunday (June 1), when "Cosmos" came in neck and neck with "The Bachelorette," nearly win the night in ratings with an episode about global warming on Earth.

"I have a feeling of just tremendous satisfaction that Fox and Nat Geo were brave enough to put this show on primetime, which hasn’t happened on a commercial broadcast network such as Fox in recent memory," Druyan said.

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afro-dominicano:

Grand Swirls

This new Hubble image shows NGC 1566, a beautiful galaxy located approximately 40 million light-years away in the constellation of Dorado (The Dolphinfish).

NGC 1566 is an intermediate spiral galaxy, meaning that while it does not have a well defined bar-shaped region of stars at its centre — like barred spirals — it is not quite an unbarred spiral either (heic9902o).

The small but extremely bright nucleus of NGC 1566 is clearly visible in this image, a telltale sign of its membership of the Seyfert class of galaxies.

The centres of such galaxies are very active and luminous, emitting strong bursts of radiation and potentially harbouring supermassive black holes that are many millions of times the mass of the Sun.

NGC 1566 is not just any Seyfert galaxy; it is the second brightest Seyfert galaxy known. It is also the brightest and most dominant member of the Dorado Group, a loose concentration of galaxies that together comprise one of the richest galaxy groups of the southern hemisphere. This image highlights the beauty and awe-inspiring nature of this unique galaxy group, with NGC 1566 glittering and glowing, its bright nucleus framed by swirling and symmetrical lavender arms.

afro-dominicano:

Chandra Helps Explain “Red and Dead Galaxies”

NASA’s Chandra X-ray Observatory has shed new light on the mystery of why giant elliptical galaxies have few, if any, young stars. This new evidence highlights the important role that supermassive black holes play in the evolution of their host galaxies.

Because star-forming activity in many giant elliptical galaxies has shut down to very low levels, these galaxies mostly house long-lived stars with low masses and red optical colors. Astronomers have therefore called these galaxies “red and dead”.

Previously it was thought that these red and dead galaxies do not contain large amounts of cold gas - the fuel for star formation - helping to explain the lack of young stars. However, astronomers have used ESA’s Herschel Space Observatory to find surprisingly large amounts of cold gas in some giant elliptical galaxies. In a sample of eight galaxies, six contain large reservoirs of cold gas. This is the first time that astronomers have seen large quantities of cold gas in giant elliptical galaxies that are not located at the center of a massive galaxy cluster.

kenobi-wan-obi:

Magnetar Formation Mystery Solved?

Magnetars are the bizarre super-dense remnants of supernova explosions.

They are the strongest magnets known in the Universe — millions of times more powerful than the strongest magnets on Earth. A team of European astronomers using ESO’s Very Large Telescope (VLT) now believe they’ve found the partner star of a magnetar for the first time.

This discovery helps to explain how magnetars form — a conundrum dating back 35 years — and why this particular star didn’t collapse into a black hole as astronomers would expect.

When a massive star collapses under its own gravity during a supernova explosion it forms either a neutron star or black hole. Magnetars are an unusual and very exotic form of neutron star.

Like all of these strange objects they are tiny and extraordinarily dense — a teaspoon of neutron star material would have a mass of about a billion tonnes — but they also have extremely powerful magnetic fields. Magnetar surfaces release vast quantities of gamma rays when they undergo a sudden adjustment known as a starquake as a result of the huge stresses in their crusts.

The Westerlund 1 star cluster, located 16 000 light-years away in the southern constellation of Ara (the Altar), hosts one of the two dozen magnetars known in the Milky Way. It is called CXOU J164710.2-455216 and it has greatly puzzled astronomers.

“In our earlier work (eso1034) we showed that the magnetar in the cluster Westerlund 1 (eso0510) must have been born in the explosive death of a star about 40 times as massive as the Sun.

But this presents its own problem, since stars this massive are expected to collapse to form black holes after their deaths, not neutron stars. We did not understand how it could have become a magnetar,” says Simon Clark, lead author of the paper reporting these results.

Astronomers proposed a solution to this mystery. They suggested that the magnetar formed through the interactions of two very massive stars orbiting one another in a binary system so compact that it would fit within the orbit of the Earth around the Sun.

But, up to now, no companion star was detected at the location of the magnetar in Westerlund 1, so astronomers used the VLT to search for it in other parts of the cluster. They hunted for runaway stars — objects escaping the cluster at high velocities — that might have been kicked out of orbit by the supernova explosion that formed the magnetar. One star, known as Westerlund 1-5, was found to be doing just that.

(via afro-dominicano)