Star discovered with oxygen atmosphere

Tags

star, white dwarf

Image 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/

Aurora over clouds

Tags

APOD, auroras, Iceland

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)

Tags

Comet 67P, Philae, Rosetta

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

Tags

God's Word, noise, planets, Sound, Universe, voices

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 – amazing!

Tags

Charon, Pluto

 New York Times online

New Horizons Reveals Ice Mountains on Pluto

By JONATHAN CORUM JULY 15, 2015

A day after its successful flyby, NASA’s New Horizons spacecraft sent back the first close-up photographs of Pluto, revealing a young surface dotted with ice mountains. The piano-size spacecraft traveled nine years and three billion miles to study the dwarf planet and its five moons.

Mountains on Pluto One of the first images returned to Earth after New Horizons’ Pluto flyby shows a small portion of Pluto’s surface seen from 47,800 miles away. Ice mountains up to 11,000 feet high — comparable to the height of the Rockies — cast shadows across a relatively smooth plain. The lack of craters indicates that the surface is quite young, no more than 100 million years old. This photo was taken early on Tuesday morning and shows an area just under the bright heart shape on Pluto’s surface.

Canyons on Charon A new image of Charon, Pluto’s largest moon. The moon has a dark patch, informally called Mordor, at its north pole. The image was taken late Monday from a distance of 289,000 miles.

Read entire interactive article here: http://www.nytimes.com/interactive/2015/07/15/science/space/new-horizons-pluto-flyby-photos.html?_r=0

The Black Hole in the Milky Way

Tags

APOD, black holes, Milky Way, Sag-A*, Sagittarius A*

Praying one day as I read an APOD (NASA’s Astronomy Picture of the Day) about black holes, I asked the Lord a question. What are they for? “Trash compactors,” he replied. Hmmm. Here’s an APOD about our own Milky Way and it’s black hole, Sag-A*.

APOD 2012 November 2
Image Credit: NASA, JPL-Caltech, NuSTAR project

At the center of our Milky Way Galaxy, a mere 27,000 light-years away, lies a black hole with 4 million times the mass of the Sun. Fondly known as Sagittarius A* (pronounced A-star), the Milky Way’s black hole is fortunately mild-mannered compared to the central black holes in distant active galaxies, much more calmly consuming material around it. From time to time it does flare-up, though.

An outburst lasting several hours is captured in this series of premier X-ray images from the orbiting Nuclear Spectroscopic Telescope Array (NuSTAR). Launched last June 13 (2011), NuSTAR is the first to provide focused views of the area surrounding Sgr A* at X-ray energies higher than those accessible to Chandra and XMM observatories.

Spanning two days of NuSTAR observations, the flare sequence is illustrated in the panels at the far right. X-rays are generated in material heated to over 100 million degrees Celsius, accelerated to nearly the speed of light as it falls into the Miky Way’s central black hole.

The main inset X-ray image spans about 100 light-years. In it, the bright white region represents the hottest material closest to the black hole, while the pinkish cloud likely belongs to a nearby supernova remnant.

http://apod.nasa.gov/apod/ap121102.html

Philae / Rosetta lander

Tags

comet, ESA, lander, NASA, Philae, Rosetta

Philae

The 100-kilogram Rosetta lander is provided by a European consortium under the leadership of the German Aerospace Research Institute (DLR). Other members of the consortium are ESA and institutes from Austria, Finland, France, Hungary, Ireland, Italy and the UK.

The box-shaped lander is carried on the side of the orbiter until it arrives at Comet 67P/Churyumov-Gerasimenko.

Once the orbiter is aligned correctly, the lander is commanded to self-eject from the main spacecraft and unfold its three legs, ready for a gentle touchdown at the end of the ballistic descent.

On landing, the legs damp out most of the kinetic energy to reduce the chance of bouncing, and they can rotate, lift or tilt to return the lander to an upright position.

Immediately after touchdown, a harpoon is fired to anchor the lander to the ground and prevent it escaping from the comet’s extremely weak gravity. The minimum mission target is one week, but surface operations may continue for many months.

Philae’s instruments

The lander structure consists of a baseplate, an instrument platform, and a polygonal sandwich construction, all made of carbon fibre. Some of the instruments and subsystems are beneath a hood that is covered with solar cells.

An antenna transmits data from the surface to Earth via the orbiter. The lander carries nine experiments, with a total mass of about 21 kilograms. It also carries a drilling system to take samples of subsurface material.

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

Landing Site / Philae lander

Tags

comet, ESA, lander, NASA, Philae, Rosetta

ESA confirms the primary landing site for Rosetta
15 October 2014

ESA has given the green light for its Rosetta mission to deliver its lander, Philae, to the primary site on 67P/Churyumov–Gerasimenko on 12 November, in the first-ever attempt at a soft touchdown on a comet.

Philae’s landing site, currently known as Site J and located on the smaller of the comet’s two ‘lobes’, was confirmed on 14 October following a comprehensive readiness review.

Since the arrival, the mission has been conducting an unprecedented survey and scientific analysis of the comet, a remnant of the early phases  of the Solar System’s 4.6 billion-year history.

At the same time, Rosetta has been moving closer to the comet: starting at 100 km on 6 August, it is now just 10 km from the centre of the 4 km-wide body. This allowed a more detailed look at the primary and backup landing sites in order to complete a hazard assessment, including a detailed boulder census.

The decision that the mission is ‘Go’ for Site J also confirms the timeline of events leading up to the landing.

Rosetta will release Philae at 08:35 GMT/09:35 CET on 12 November at a distance of approximately 22.5 km from the centre of the comet. Landing will be about seven hours later at around 15:30 GMT/16:30 CET.

With a one-way signal travel time between Rosetta and Earth on 12 November of 28 minutes 20 seconds, that means that confirmation of separation will arrive on Earth ground stations at 09:03 GMT/10:03 CET and of touchdown at around 16:00 GMT/17:00 CET.

A short manoeuvre must then take place around two hours before separation. This will set Rosetta on course to release Philae on the right trajectory to land on the comet. The final critical Go/No-Go for separation occurs shortly after this manoeuvre.

After the release of Philae, Rosetta will manoeuvre up and away from the comet, before reorienting itself in order to establish communications with Philae. All being well, Rosetta and its lander will begin communications about two hours after separation.

During the seven-hour descent, Philae will take images and conduct science experiments, sampling the dust, gas and plasma environment close to the comet.

It will take a ‘farewell’ image of the Rosetta orbiter shortly after separation, along with a number of images as it approaches the comet surface. It is expected that the first images from this sequence will be received on Earth several hours after separation.

Once safely on the surface, Philae will take a panorama of its surroundings. Again, this is expected back on Earth several hours later.

The first sequence of surface science experiments will begin about an hour after touchdown and will last for 64 hours, constrained by the lander’s primary battery lifetime.

Longer-term study of the comet by Philae will depend on for how long and how well the batteries are able to recharge, which in turn is related to the amount of dust that settles on its solar panels.

In any case, it is expected that by March 2015, as the comet moves closer in its orbit towards the Sun, temperatures inside the lander will have reached levels too high to continue operations, and Philae’s science mission will come to an end.

The Rosetta orbiter’s mission will continue for much longer. It will accompany the comet as it grows in activity until their closest approach to the Sun in August 2015 and then as they head back towards the outer Solar System.

This unprecedented mission will study how a comet evolves and give important insights into the formation of our Solar System, and the origins of water and perhaps even life on Earth.

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

Cometwatch / Rosetta

Tags

comet, ESA, NASA, Rosetta

ESA – European Space Agency
Rosetta Blog

Cometwatch – 28 October

This four-image NAVCAM montage comprises images taken on 28 October – shortly before moving to the pre-lander delivery orbit – from a distance of 9.7 km from the centre of comet 67P/C-G, or roughly 7.7 km from the surface.

The corresponding image scale is about 65 cm/pixel, so each 1024 x 1024 pixel frame is about 665 m across. The montage has been slightly tweaked and the central vignetting reduced. The four original frames are provided at the end of the post.

The montage nicely ‘joins the dots’ with the region presented in the 8 October montage.

Given the peculiar low-density, low-gravity nature of a comet, it is perhaps dangerous to make direct analogies with Earth-like features and processes. But until we have the science team’s analysis of what they think is actually happening on this comet, analogies might nevertheless still provide a useful way of trying to decipher what we are seeing.

In a number of places in this region, there is an impression that the prevalent dusty material covering the surface is not particularly stable and that it occasionally gives way, perhaps in a similar way that snow on a mountain side may become dislodged, giving rise to an avalanche or, alternatively, a rockfall or landslide.

For example, look in the lower third of the top left image. There you’ll see what looks like a crack close to the edge of the cliff, suggesting that this portion might eventually collapse, similar to the way a snow cornice on a mountain ridge peels away. This feature is also visible in the 8 October image.

Another example can be seen in the lower right corner of the bottom right image, where material appears to have slid over the edge of a cliff.

On Earth, avalanches are typically triggered by an increased load, leading to the mechanical failure of a slab of material under gravity, or due to melting snow as a result of increased solar radiation. On a comet, presumably the latter process is more likely to occur, with sublimation-based erosion acting to weaken the surface material, resulting in a collapse.

http://blogs.esa.int/rosetta/2014/10/31/cometwatch-28-october/

Also see:
http://www.esa.int/spaceinimages/Images/2014/10/Comet_on_28_October_NavCam

Rosetta and the comet

Tags

comet, ESA, Rosetta

Comet 67P on Aug. 3, 2014. ESA’s Rosetta probe snapped this image of its target, Comet 67P on Aug. 3, 2014 from a distance of 177 miles (285 kilometers). Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

I’ve been following the progress of the ESA Rosetta spacecraft recently as it neared Comet 67P/Churyumov-Gerasimenko.

After a ten-year journey, today it arrived!

Here’s a link to the ESA live broadcast this morning. http://www.space.com/17933-nasa-television-webcasts-live-space-tv.html

More about Rosetta and the comet from Space.com online today:

Europe’s Rosetta Spacecraft Makes Historic Arrival at Comet
By Miriam Kramer, Staff Writer | August 06, 2014 06:00am ET

After a decade in space and 4 billion miles, Europe’s Rosetta spacecraft has made history: For the first time ever, a robotic probe from Earth is flying with a comet and will soon enter orbit.

The European Space Agency’s Rosetta spacecraft arrived at its target, Comet 67P/Churyumov-Gerasimenko, today (Aug. 6) to end a 10-year journey across the solar system. The spacecraft performed an engine burn that brought it about 62 miles (100 kilometers) from the comet’s surface.

Comet 67P/C-G and Rosetta are now flying about 251 million miles (450 million kilometers) from Earth. Engineers on the ground had to program the probe to go through a series of complicated burns and maneuvers to make the spacecraft’s rendezvous with the comet a possibility.

“This is the end of 10 years of interplanetary flight,” Rosetta Flight Director Andrea Accomazzo said during ESA’s live comet rendezvous webcast Wednesday.

Applause broke out in Rosetta’s mission control center in Darmstadt, Germany, where a crowd of ESA dignitaries and officials had gathered to watch the historic event.

“We’re at the comet! Yes!” exclaimed Sylvain Lodiot, Rosetta’s spacecraft operations manager, once the probe’s successful arrival at Comet 67P/C-G was confirmed.
….

Rosetta is expected to stay in orbit around Comet 67P/C-G until the end of 2015. “We’re going to going to ride along with this comet. We’re going to have a ringside seat,” Matt Taylor, ESA Rosetta project scientist, said Wednesday as the spacecraft arrived at Comet 67P/C-G. “It’s going to be an awesome ride. Stay tuned.”

Link to entire article: http://www.space.com/26740-rosetta-spacecraft-comet-arrival.html