Star discovered with oxygen atmosphere

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whitedwarfImage of Sirius A and Sirius B taken by the Hubble Space Telescope. Sirius B, which is a white dwarf, can be seen as a faint pinprick of light to the lower left of the much brighter Sirius A. Image: NASA, ESA

Astronomers spot a never-before-seen type of white dwarf star; its discovery could change our understanding of star death

By Loren Grush / The Verge online / March 31, 2016

For the first time ever, researchers have spotted a white dwarf surrounded by an atmosphere of mostly oxygen. A star of this kind, a super-dense dead star with an oxygen atmosphere, had never been seen before, though astronomers had speculated that one might exist. Such a unique finding could change how we think about the evolution of stars and what happens when these stellar objects die.

“It was completely not expected.”

To find this unique zombie star, an international team of researchers looked through data from the Sloan Digital Sky Survey — a project that measures the colored lines of light coming off of objects throughout the universe. These lines, called spectral lines, can tell astronomers what types of elements make up a star’s atmosphere. Using this data, the researchers found that one particular white dwarf, with the eloquent name ­­SDSS J124043.01+671034.68, didn’t have any hydrogen or helium in its atmosphere; its surrounding air was instead almost pure oxygen.

“It was completely not expected for a star with a low mass like our star,” said study author Kepler Oliveira, an astronomer at the Federal University of Rio Grande do Sul.

An image of SDSS J124043.01+671034.68. (Kepler Oliveira)

The finding is so surprising because it doesn’t quite fit with our current understanding of what stars look like when they die. Typically, when a star like our Sun runs out of fuel, it starts collapsing. As the star becomes more compact, it heats up, causing its outer layers to expand more than 100 times the star’s original size. Eventually those outer layers are lost and only the core of the star remains — the faint white dwarf.

Most of the star’s hydrogen and helium get lost with those outer layers, but a little bit of them are left over in the white dwarf’s atmosphere. The hydrogen and helium float to the top of the star’s surface, because they’re relatively light; the heavier elements, like oxygen and carbon, remain below.

“It’s the same reason that panning for gold works,” said Andrew Vanderburg, an astronomy graduate student at Harvard University, who was not involved in the study. “If you have gold and sediments in water, the gold is heavier so it’ll sink to the bottom, but the sediments are lighter, so they’ll stay at the top.”

Some kind of event caused the hydrogen and helium to disappear

The fact that no hydrogen and helium are seen in the atmosphere of the white dwarf in question is puzzling. It means some kind of event has caused the two elements to disappear, making oxygen the lightest element in the star’s atmosphere. But the researchers aren’t sure what kind of event that was, as they’ve never considered it before. “We don’t make models of things we don’t know exist,” Oliveira said. “But now that we know this star exists, we have to calculate the model for it.”

One possible explanation for the lack of helium and hydrogen is that the star experienced a giant thermal pulse when the object was a red giant, and that intense explosion stripped away all the lighter elements. Another possible scenario is that the star was actually part of a binary system. The stars may have merged together, causing an explosion that ejected the hydrogen and helium. These ideas are only loose theories, though. “We don’t have a calculation that shows [a binary merger] happened, but that’s the only explanation that I can think of,” Oliveira said. “It must have come from a binary system.”

The researchers will work to figure out what happened to this star, but in the meantime, the white dwarf’s discovery is a significant find for the astronomy community. “It’s a new class of star,” said Vanderburg. “We don’t understand how it formed, but this is the kind of thing that pushes our field forward, and who knows where it will take us.”

http://www.theverge.com/2016/3/31/11338590/white-dwarf-star-oxygen-atmosphere-stellar-death

Also see http://www.popularmechanics.com/space/deep-space/a20213/newly-discovered-star-has-an-almost-pure-oxygen-atmosphere/

APOD (Astronomy Picture of the Day)

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APOD is one of the sites I subscribe to and one of my favorites. God’s marvelous creations – and the technology to view it – never fail to amaze me, awe me, and cause me to love Him more, the one who created it all with such loving detail. Click on the photo to enlarge.

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2016 March 24
See Explanation. Clicking on the picture will download the highest resolution version available.

Hickson 91 in Piscis Austrinus
Image Credit & Copyright: CHART32 Team, Processing – Johannes Schedler Explanation: Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups (HCGs). This sharp telescopic image captures one such galaxy group, HCG 91, in beautiful detail. The group’s three colorful spiral galaxies at the center of the field of view are locked in a gravitational tug of war, their interactions producing faint but visible tidal tails over 100,000 light-years long. Their close encounters trigger furious star formation. On a cosmic timescale the result will be a merger into a large single galaxy, a process now understood to be a normal part of the evolution of galaxies, including our own Milky Way. HCG 91 lies about 320 million light-years away in the constellation Piscis Austrinus. But the impressively deep image also catches evidence of fainter tidal tails and galaxy interactions close to 2 billion light-years distant.

Tomorrow’s picture: close comet


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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Aurora over clouds

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Image Credit & Copyright: Daniele Boffelli

Explanation: Auroras usually occur high above the clouds. The auroral glow is created when fast-moving particles ejected from the Sun impact the Earth’s magnetosphere, from which charged particles spiral along the Earth’s magnetic field to strike atoms and molecules high in the Earth’s atmosphere. An oxygen atom, for example, will glow in the green light commonly emitted by an aurora after being energized by such a collision. The lowest part of an aurora will typically occur at 100 kilometers up, while most clouds usually exist only below about 10 kilometers.

The relative heights of clouds and auroras are shown clearly in the featured picture from Dyrholaey, Iceland. There, a determined astrophotographer withstood high winds and initially overcast skies in an attempt to a capture aurora over a picturesque lighthouse, only to take, by chance, the featured picture along the way.

(This is the Nasa APOD from 24 November 2015. Click here for many more wonderful images. http://apod.nasa.gov/apod/astropix.html)

The long trek (Rosetta, Philae)

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http://www.esa.int/spaceinvideos/content/view/embedjw/421241
Click for Video – Reconstructing Philae’s flight

12 November 2015

One year since Philae made its historic landing on a comet, mission teams remain hopeful for renewed contact with the lander, while also looking ahead to next year’s grand finale: making a controlled impact of the Rosetta orbiter on the comet.

Rosetta arrived at Comet 67P/Churyumov–Gerasimenko on 6 August 2014, and after an initial survey and selection of a landing site, Philae was delivered to the surface on 12 November.

After touching down in the Agilkia region as planned, Philae did not secure itself to the comet, and it bounced to a new location in Abydos. Its flight across the surface is depicted in a new animation, using data collected by Rosetta and Philae to reconstruct the lander’s rotation and attitude.

In the year since landing, a thorough analysis has also now been performed on why Philae bounced.

There were three methods to secure it after landing: ice screws, harpoons and a small thruster. The ice screws were designed with relatively soft material in mind, but Agilkia turned out to be very hard and they did not penetrate the surface.

The harpoons were capable of working in both softer and harder material. They were supposed to fire on contact and lock Philae to the surface, while a thruster on top of the lander was meant to push it down to counteract the recoil from the harpoon.

Attempts to arm the thruster the night before failed: it is thought that a seal did not open, although a sensor failure cannot be excluded.

Then, on landing, the harpoons themselves did not fire. “It seems that the problem was either with the four ‘bridge wires’ taking current to ignite the explosive that triggers the harpoons, or the explosive itself, which may have degraded over time,” explains Stephan Ulamec, Philae lander manager at the DLR German Aerospace Center.

“In any case, if we can regain contact with Philae, we might consider an attempt to retry the firing.”

The reason is scientific: the harpoons contain sensors that could measure the temperature below the surface.

Despite the unplanned bouncing, Philae completed 80% of its planned first science sequence before falling into hibernation in the early hours of 15 November when the primary battery was exhausted. There was not enough sunlight in Philae’s final location at Abydos to charge the secondary batteries and continue science measurements.

The hope was that as the comet moved nearer to the Sun, heading towards closest approach in August, there would be enough energy to reactivate Philae. Indeed, contact was made with the lander on 13 June but only eight intermittent contacts were made up to 9 July.

The problem was that the increasing sunlight also led to increased activity on the comet, forcing Rosetta to retreat to several hundred kilometres for safety, well out of range with Philae.

However, over the past few weeks, with the comet’s activity now subsiding, Rosetta has started to approach again. This week it reached 200 km, the limit for making good contact with Philae, and today it dips to within 170 km.

(Click on link and read entire article for more of this fascinating story.)

http://www.esa.int/Our_Activities/Space_Science/Rosetta/The_long_trek

Sounds of the universe

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Someone shared an article about sounds made by planets on Facebook a week or so ago. It’s been in the back of my mind ever since.  It seems that for some years now NASA has recorded sound waves occurring in space. Some of them sound absolutely bone chilling.

The article includes a number of video/audio recordings from multiple planets (including earth). Here’s one of them – The Eerie Sounds of Saturn:

(http://www.youtube.com/watch?v=Sh2-P8hG5-E)

“There are, it may be, so many kinds of voices in the world, and none of them is without signification.” (I Cor. 14:10 KJV) This verse is translated into English several ways, and considering the context of speaking in unknown tongues, they all express the idea that there are multiple languages in the world and each one has meaning.

However, I discovered that the original Greek words can also be translated “multiple sounds or noises in the universe, and each one has meaning.” Sounds. Universe. Hmmmmmm.

I discussed this article with the Lord the other night, asking him about sounds made by various planets. He began to explain a few things. Just matter of fact things, physics, nothing particularly spiritual, but fascinating to me.

Sound waves, like visual images, contain information. Each sound contains a specific piece of information, and if interpreted (translated) accurately by the receiver, it transmits that data to him.

He had me listen to the sounds I could hear from my bedroom and asked what information I received from each sound. Trucks. What size? Pickup trucks sound different than 18-wheelers. Train whistles. Motorcycles. Car brakes. Cars changing gears. Various automobiles going by the highway.

Ceiling fan. Humming from deodorizer. Heat pump. Footsteps walking overhead. Lighter footsteps, running. Clocks ticking. Even my own breathing, my own heart beat, the constant tinnitus I’ve had for many years… I fell asleep thinking about all the sounds that I could hear, and what data I received from each one.

Last night we continued the conversation about sound.

Every created thing makes sound, because it moves. The wind is air movement, and because it is moving, it makes sound. Creation could have been silent, made without the capacity to make noise. But it wasn’t. There was a reason for the sound, the noise, the voices.

All senses convey information / data. Some can be from close or at a distance, such as sound and sight. Others are near by, such as smell. Others must be up close and personal, such as taste and touch.

Far or near, each use of those senses brings us information which can be useful – if we pay attention to it, think about what the data is saying to us and how we can best benefit from it. Even the sounds recorded by NASA, sounds made by planets, stars, asteroids, comets, meteors, even sounds made by atoms, molecules, and subatomic particles.

Every cell of every creature and creation, from infinitesimally microscopic to majestically huge, has the capacity to make sound and transmit data. And all that information is beneficial in some way, for some purpose, to someone.

Jesus is the Word of God. God’s voice. What a mind-boggling concept! Jesus is both God and God’s expression. Creator of everything that exists, he is also maintainer, sustainer of it. Information-bringer. Explainer. Teacher. Guide. Rescuer. Healer. Provider. Lover. Friend.

Every sound of the universe, every noise, every voice, every burst of static, every clang of metal, every crash of breaking waves, every whisper of wind in trees, every murmur of nesting birds, every hum of a mother’s lullaby – all are expressions containing data.

So – I was thinking. So – what is the bottom line of all that? I asked the Lord.

Well, what is the most essential data? he replied. Then he answered the question himself. Love. God’s love, holiness, justice, mercy, affection, creativity, mindfulness, unwavering attention to his creation. His most highly treasured creation – his children.

http://damn.com/nasa-space-sound/

Pluto is just one of many TNOs

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TNOsEightTNOsCharon compared with Eris, Pluto, Makemake, Haumea, Sedna, Orcus, 2007 OR10, Quaoar, their moons and Earth. All to scale.

The center of mass (barycenter) of the Pluto–Charon system lies outside either body. Because neither object truly orbits the other, and Charon has 11.6% the mass of Pluto, it has been argued that Charon should be considered to be part of a binary system. The International Astronomical Union (IAU) states that Charon is considered to be just a satellite of Pluto, but the idea that Charon might be classified a dwarf planet in its own right may be considered at a later date.

Excerpted from Wikipedia’s entry about Charon. https://en.wikipedia.org/wiki/Charon_%28moon%29

Pluto – amazing!

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 New York Times online

Rosetta mission extended

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23 June 2015The adventure continues: ESA today confirmed that its Rosetta mission will be extended until the end of September 2016, at which point the spacecraft will most likely be landed on the surface of Comet 67P/Churyumov-Gerasimenko.

Rosetta was launched in 2004 and arrived at the comet in August 2014, where it has been studying the nucleus and its environment as the comet moves along its 6.5-year orbit closer to the Sun. After a detailed survey, Rosetta deployed the lander, Philae, to the surface on 12 November. Philae fell into hibernation after 57 hours of initial scientific operations, but recently awoke and made contact with Rosetta again.

Rosetta’s nominal mission was originally funded until the end of December 2015, but at a meeting today, ESA’s Science Programme Committee has given formal approval to continue the mission for an additional nine months. At that point, as the comet moves far away from the Sun again, there will no longer be enough solar power to run Rosetta’s set of scientific instrumentation efficiently.

“This is fantastic news for science,” says Matt Taylor, ESA’s Rosetta Project Scientist. “We’ll be able to monitor the decline in the comet’s activity as we move away from the Sun again, and we’ll have the opportunity to fly closer to the comet to continue collecting more unique data. By comparing detailed ‘before and after’ data, we’ll have a much better understanding of how comets evolve during their lifetimes.”

Comet on 5 June 2015 – NavCam

Comet 67P/Churyumov-Gerasimenko will make its closest approach to the Sun on 13 August and Rosetta has been watching its activity increase over the last year. Continuing its study of the comet in the year following perihelion will give scientists a fuller picture of how a comet’s activity waxes and wanes along its orbit.

The extra observations collected by Rosetta will also provide additional context for complementary Earth-based observations of the comet. At present, the comet is close to the line-of-sight to the Sun, making ground-based observations difficult.

As the activity diminishes post-perihelion, it should be possible to move the orbiter much closer to the comet’s nucleus again, to make a detailed survey of changes in the comet’s properties during its brief ‘summer’.

In addition, there may be an opportunity to make a definitive visual identification of Philae. Although candidates have been seen in images acquired from a distance of 20 km, images taken from 10 km or less after perihelion could provide the most compelling confirmation.

During the extended mission, the team will use the experience gained in operating Rosetta in the challenging cometary environment to carry out some new and potentially slightly riskier investigations, including flights across the night-side of the comet to observe the plasma, dust, and gas interactions in this region, and to collect dust samples ejected close to the nucleus.

As the comet recedes from the Sun, the solar-powered spacecraft will no longer receive enough sunlight to operate efficiently and safely, equivalent to the situation in June 2011 when the spacecraft was put into hibernation for 31 months for the most distant leg of its journey out towards the orbit of Jupiter.

In addition, Rosetta and the comet will again be close to the Sun as seen from the Earth in October 2016, making operations difficult by then.

However, with Rosetta’s propellant largely depleted by that time, it makes little sense to place the spacecraft in hibernation again.

“This time, as we’re riding along next to the comet, the most logical way to end the mission is to set Rosetta down on the surface,” says Patrick Martin, Rosetta Mission Manager.

“But there is still a lot to do to confirm that this end-of-mission scenario is possible. We’ll first have to see what the status of the spacecraft is after perihelion and how well it is performing close to the comet, and later we will have to try and determine where on the surface we can have a touchdown.”

If this proposed scenario were played out, then the spacecraft would be commanded to spiral down to the comet over a period of about three months.

It is expected that science operations would continue throughout this period and be feasible up to very close to the end of mission, allowing Rosetta’s instruments to gather unique data at unprecedentedly close distances.

Once the orbiter lands on the surface, however, it is highly unlikely to be able to continue operations and relay data back to Earth, bringing to an end one of the most successful space exploration missions of all time.

http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_mission_extended

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 Rosetta’s MIRO Instrument Maps Comet Water

Comet67PNASAPhotoThis image, by the Rosetta navigation camera, was taken from a distance of about 53 miles (86 kilometers) from the center of Comet 67P/Churyumov-Gerasimenko on March 14, 2015. The image has a resolution of 24 feet (7 meters) per pixel and is cropped and processed to bring out the details of the comet’s activity.

Since last September, scientists using NASA’s Microwave Instrument for Rosetta Orbiter (MIRO) on the European Space Agency’s Rosetta spacecraft have generated maps of the distribution of water in the coma of comet 67P/Churyumov-Gerasimenko, as the comet’s orbit brings it closer to the sun.

MIRO is able to detect water in the coma by measuring the direct emission from water vapor in the coma and by observing absorption of radiation from the nucleus at water-specific frequencies as the radiation passed through the coma.

For the rest of the article, click here:
http://www.nasa.gov/feature/rosettas-miro-instrument-maps-comet-water

NASA’s New Horizons Sees More Detail as It Draws Closer to Pluto

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May 27, 2015

PlutoViaNewHorizonsSpacecraftMay2015
What a difference 20 million miles makes! Images of Pluto from NASA’s New Horizons spacecraft are growing in scale as the spacecraft approaches its mysterious target.

The new images, taken May 8-12 using a powerful telescopic camera and down-linked last week, reveal more detail about Pluto’s complex and high contrast surface.

http://www.nasa.gov/feature/nasa-s-new-horizons-sees-more-detail-as-it-draws-closer-to-pluto

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