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Posts tagged "astronomy"

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)

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Partial Eclipse at Moonrise by David Malin

A partial lunar eclipse at Moonrise is photographed in a multi-exposure image from Port Hedland, Western Australia.

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Cygnus X-1

This image only shows part of the black hole jet powered bowshock nebula associated with Cygnus X-1.

Copyright: T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOAO/AURA/NSF)

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IC4628 by Paul Haese

Prawn Nebula, IC 4628, is an emission nebula located around 6000 light-years from Earth in the constellation of Scorpius.

Propeller Nebula in SHO by Didier CHAPLAIN & Laurent BOURGON

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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

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Should Humanity Try to Contact Intelligent Aliens?

Astronomers have detected nearly 2,000 alien planets to date. As that number continues to rise, so too does the prospect of finding intelligent extraterrestrial life.

In terms of the search for extraterrestrial intelligence (SETI), it may no longer be a matter of answering the “are we alone” question, some scientists say. Rather, just how crowded is the universe?

Continue Reading

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humanoidhistory:

The International Space Station cruises over the Pacific at 28,000kph. Sourced from a Vine sent by astronaut Reid Wiseman.

humanoidhistory:

The International Space Station cruises over the Pacific at 28,000kph. Sourced from a Vine sent by astronaut Reid Wiseman.

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IC 4604 in Widefield by Rogelio Bernal Andreo

The IC 4604 cloud complex is a dark nebula of gas and dust that is located 1° south of the star ρ Ophiuchi of the constellation Ophiuchus.

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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.

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Mars One Wants to Send Your Experiments to the Red Planet

The nonprofit organization that has raised eyebrows with its plans to send people on a one-way mission to Mars is now accepting proposals for scientific payloads that could fly aboard an unmanned mission to the Red Planet in 2018.

Image: The non-profit Mars One organization wants to send a lander to the Red Planet in 2018. The lander will have seven different science payloads, and people everywhere can submit their ideas to the organization now. Credit: Bryan Versteeg/Mars One Foundation

The Netherlands-based Mars One foundation aims to send a total of seven payloads: four demonstration payloads, one payload selected in a worldwide university competition and two payloads for sale to the highest bidder.

The unmanned 2018 mission will serve as preparation for a planned human mission to Mars in 2024, Mars One organizers said. As of May, the nonprofit had whittled down its pool of potential astronauts to 705 candidates. Mars One aims to send four people on a one-way trip to the Red Planet every two years, starting in 2024.

Mars One is asking for input from the scientific community in order to source the best ideas from around the world, Arno Wielders, co-founder and chief technical officer of Mars One, said in a statement.

"The ideas that are adopted will not only be used on the lander in 2018, but will quite possibly provide the foundation for the first human colony on Mars," Wielders said.

Mars One is expected to send these payloads aboard the lander that is scheduled to launch in August 2018 and will be built on the same platform used for NASA’s 2007 Phoenix mission. Mars One and Lockheed Martin are partnering to develop a mission concept for the lander.

The four demonstration payloads will test technologies needed for the permanent human settlement of Mars. These will include an experiment to collect Martian soil for water production, an experiment to extract water from the soil, a thin-film solar panel for energy generation and a camera system that will interface with a Mars-synchronous communications satellite that will relay live video to Earth, according to Mars One.