The Contributor to SN 2011fe

Astrophoto: Supernova PTF11kly in M101 by Rick Johnson
Supernova PTF11kly in M101. Credit: Rick Johnson

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When discovered on August 24, 2011, supernova 2011fe was the closest supernova since the famous SN 1987A. Located in the relatively nearby Pinwheel galaxy (M101), it was a prime target for scientists to study since the host galaxy has been well studied and many high resolution images exist from before the explosion, allowing astronomers to search them for information on the star that led to the eruption. But when astronomers, led by Weidong Li, at the University of California, Berkeley searched, what they found defied the typically accepted explanations for supernovae of the same type as 2011fe.

SN 2011fe was a type 1a supernova. This class of supernova is expected to be caused by a white dwarf which accumulates mass contributed by a companion star. The general expectation is that the companion star is a star evolving off the main sequence. As it does, it swells up, and matter spills onto the white dwarf. If this pushes the dwarf’s mass over the limit of 1.4 times the mass of the Sun, the star can no longer support the weight and it undergoes a runaway collapse and rebound, resulting in a supernova.

Fortunately, the swollen up stars, known as red giants, become exceptionally bright due to their large surface area. The eighth brightest star in our own sky, Betelgeuse, is one of these red giants. This high brightness means that these objects are visible from large distances, potentially even in galaxies as distant as the Pinwheel. If so, the astronomers from Berkeley would be able to search archival images and detect the brighter red giant to study the system prior to the explosion.

But when the team searched the images from the Hubble Space Telescope which had snapped pictures through eight different filters, no star was visible at the location of the supernova. This finding follows a quick report from September which announced the same results, but with a much lower threshold for detection. The team followed up by searching images from the Spitzer infrared telescope which also failed to find any source at the proper location.

While this doesn’t rule out the presence of the contributing star, it does place constraints on its properties. The limit on brightness means that the contributor star could not have been a luminous red giant. Instead, the result favors another model of mass donation known as a double-degenerate model

In this scenario, two white dwarfs (both supported by degenerate electrons) orbit one another in a tight orbit. Due to relativistic effects, the system will slowly lose energy and eventually the two stars will become close enough that one will become disrupted enough to spill mass onto the other. If this mass transfer pushes the primary over the 1.4 solar mass limit, it would trigger the same sort of explosion.

This double degenerate model does not exclusively rule out the possibility of red giants contributing to type Ia supernovae, but recently other evidence has revealed missing red giants in other cases.

Solar Powered Dragon gets Wings for Station Soar

SpaceX Dragon set to dock at International Space Station on COTS 2/3 mission. Falcon 9 launch of Dragon on COTS 2/3 mission is slated for Feb.7, 2012 from pad 40 at Cape Canaveral, Florida. Artist’s rendition of Dragon spacecraft with solar panels fully deployed on orbit. ISS crew will grapple Dragon and berth to ISS docking port. Credit: NASA

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The Dragon has grown its mighty wings

SpaceX’s Dragon spacecraft has gotten its wings and is set to soar to the International Space Station (ISS) in about a month. NASA and SpaceX are currently targeting a liftoff on Feb. 7 from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida.

Dragon is a commercially developed unmanned cargo vessel constructed by SpaceX under a $1.6 Billion contract with NASA. The Dragon spacecraft will launch atop a Falcon 9 booster rocket also built by SpaceX, or Space Exploration Technologies.

Dragon’s solar array panels being installed on Dragon’s trunk at the SpaceX hangar in Cape Canaveral,FL.

The Feb. 7 demonstration flight – dubbed COTS 2/3 – represents the first test of NASA’s new strategy to resupply the ISS with privately developed rockets and cargo carriers under the Commercial Orbital Transportation Services (COTS) initiative.

Following the forced retirement of the Space Shuttle after Atlantis final flight in July 2011, NASA has no choice but to rely on private companies to loft virtually all of the US share of supplies and equipment to the ISS.

The Feb. 7 flight will be the first Dragon mission actually tasked to dock to the ISS and is also the first time that the Dragon will fly with deployable solar arrays. The twin arrays are the primary power source for the Dragon. They will be deployed a few minutes after launch, following Dragon separation from the Falcon 9 second stage.

The solar arrays can generate up to 5000 watts of power on a long term basis to run the sensors and communications systems, drive the heating and cooling systems and recharge the battery pack.

SpaceX designed, developed and manufactured the solar arrays in house with their own team of engineers. As with all space hardware, the arrays have been rigorously tested for hundreds of hours under the utterly harsh conditions that simulate the unforgiving environment of outer space, including thermal, vacuum, vibration, structural and electrical testing.

SpaceX engineers conducting an early solar panel test. Hundreds of flood lamps simulate the unfiltered light of the sun. Photo: Roger Gilbertson/ SpaceX

The two arrays were then shipped to Florida and have been attached to the side of the Dragon’s bottom trunk at SpaceX’s Cape Canaveral launch processing facilities. They are housed behind protective shielding until commanded to deploy in flight.


Video Caption: SpaceX testing of the Dragon solar arrays. Credit: SpaceX

I’ve toured the SpaceX facilities several times and seen the Falcon 9 and Dragon capsule launching on Feb. 7. The young age and enthusiasm of the employees is impressive and quite evident.

NASA recently granted SpaceX the permission to combine the next two COTS demonstration flights into one mission and dock the Dragon at the ISS if all the rendezvous practice activities in the vicinity of the ISS are completed flawlessly.

Dragon with the protective fairings installed over the folded solar arrays, at the SpaceX

The ISS crew is eagerly anticipating the arrival of Dragon, for whch they have long trained.

“We’re very excited about it,” said ISS Commander Dan Burbank in a televised interview from on board the ISS earlier this week.

The ISS crew will grapple the Dragon with the station’s robotic arm when it comes within reach and berth it to the Earth-facing port of the Harmony node.

“From the standpoint of a pilot it is a fun, interesting, very dynamic activity and we are very much looking forward to it,” Burbank said. “It is the start of a new era, having commercial vehicles that come to Station.”

Burbank is a US astronaut and captured stunning images of Comet Lovejoy from the ISS just before Christmas, collected here.

Read recent features about the ISS and commercial spaceflight by Ken Kremer here:
Dazzling Photos of the International Space Station Crossing the Moon!
Absolutely Spectacular Photos of Comet Lovejoy from the Space Station
NASA announces Feb. 7 launch for 1st SpaceX Docking to ISS

Jan 11: Free Lecture by Ken at the Franklin Institute, Philadelphia, PA at 8 PM for the Rittenhouse Astronomical Society. Topic: Mars & Vesta in 3 D – Plus Search for Life & GRAIL

Tranquillityite – Moon Mineral Found In Western Australia

A mineral brought back to Earth by the first men on the Moon and long thought to be unique to the lunar surface has been found in Australian rocks more than one billion years old, scientists say. Image Credit: Birger Rasmussen

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When it comes to our natural human curiosity, we want to know if there’s something new out there… something we haven’t discovered yet. That’s why when lunar rock samples were returned, geologists were thrilled to find very specific minerals – armalcolite, pyroxferroite and tranquillityite – which belonged only to our Moon. However, over the years the first two were found here on Earth and tranquillityite was disclosed in specific meteorites. Named for Tranquility Base, site of the first Moon landing, tranquillityite was supposed to be the final hold-out… the last lunar unique mineral… until now.

Birger Rasmussen, paleontologist with Curtin University in Perth, and colleagues report in their Geology paper that they’ve uncovered tranquillityite in several remote locations in Western Australia. While the samples are incredibly small, about the width of a human hair and merely microns in length, their composition is undeniable. What’s more, tranquillityite may be a lot more common here on Earth than previously thought.

Rasmussen told the Sydney Morning Herald, “This was essentially the last mineral which was sort of uniquely lunar that had been found in the 70s from these samples returned from the Apollo mission.The mineral has since been found exclusively in returned lunar samples and lunar meteorites, with no terrestrial counterpart. We have now identified tranquillityite in six sites from Western Australia.”

Why has this remote mineral stayed hidden for so long? One major reason is its delicate structure. Composed of iron, silicon, oxygen, zirconium, titanium and a tiny bit of yttrium, a rare earth element, tranquillityite erodes at a rapid pace when exposed to natural environmental conditions. Another explanation is that tranquillityite can only form through a unique set of circumstance – through uranium decay. Rasmussen explains it’s evidence these minerals were ‘always’ located here on Earth and we share the same chemical processes as our satellite.

“This means that basically we have the same chemical phenomena on the Moon and on Earth.” says Rasmussen. And one of the reasons it has taken so long to be found is, “No one was looking hard enough.”

Image Credit: Birger Rasmussen
And exactly what does it take to locate it? More than a billion years old, the only sure way to identify tranquillityite is to subject it to a series of electron blasts. By exposing it to a high-energy accelerating electron beam, it produces spectra. From there “an elemental composition in combination with back-scattered electron (BSE) brightness and x-ray count rate information is converted into mineral phases.” According to Rasmussen’s paper, “Terrestrial tranquillityite commonly occurs as clusters of fox-red laths closely associated with baddeleyite and zirconolite in quartz and K-feldspar intergrowths in late-stage interstices between plagioclase and pyroxene.”

While it has no real economic value, terrestrial tranquillityite is another good reason mankind should try to preserve pristine regions such as the northeast Pilbara Region and the Eel Creek formation. Who knows what else we might find?

Original Story Source: PhysOrg.com.

Journal Club: On Nothing

Today's Journal Club is about a new addition to the Standard Model of fundamental particles.

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According to Wikipedia, a journal club is a group of individuals who meet regularly to critically evaluate recent articles in scientific literature. Being Universe Today if we occasionally stray into critically evaluating each other’s critical evaluations, that’s OK too. And of course, the first rule of Journal Club is… don’t talk about Journal Club.

So, without further ado – today’s journal article under the spotlight is about nothing.

The premise of the article is that to define nothing we need to look beyond a simple vacuum and think of nothing in terms of what there was before the Big Bang – i.e. really nothing.

For example, you can have a bubble of nothing (no topology, no geometry), a bubble of next to nothing (topology, but no geometry) or a bubble of something (which has topology, geometry and most importantly volume). The universe is a good example of a bubble of something.

The paper walks the reader through a train of logic which ends by defining nothing as ‘anti De Sitter space as the curvature length approaches zero’. De Sitter space is essentially a ‘vacuum solution’ of Einstein’s field equations – that is, a mathematically modelled universe with a positive cosmological constant. So it expands at an accelerating rate even though it is an empty vacuum. Anti De Sitter space is a vacuum solution with a negative cosmological constant – so it’s shrinking inward even though it is an empty vacuum. And as its curvature length approaches zero, you get nothing.

Having so defined nothing, the authors then explore how you might get a universe to spontaneously arise from that nothing – and nope, apparently it can’t be done. Although there are various ways to enable ‘tunnelling’ that can produce quantum fluctuations within an apparent vacuum – you can’t ‘up-tunnel’ from nothing (or at least you can’t up-tunnel from ‘anti-de Sitter space as the curvature length approaches zero’ ).

The paper acknowledges this is obviously a problem, since here we are. By explanation, the authors suggest:

  • get past the problem by appealing to immeasurable extra dimensions (a common strategy in theoretical physics to explain impossible things without anyone being able to easily prove or disprove it);
  • that their definition of nothing is just plain wrong; or
  • that they (and we) are just not asking the right questions.

Clearly the third explanation is the authors’ favoured one as they end with the statement: ‘One thing seems clear… to truly understand everything, we must first understand nothing‘. Nice.

So – comments? Is appealing to extra dimensions just a way of dodging a need for evidence? Nothing to declare? Want to suggest an article for the next edition of Journal Club?

Today’s article:
Brown and Dahlen On Nothing.

Virtual Star Parties, More Astronomers Needed

For those of you following me on Google+, you know that I’ve been hosting virtual star parties with Phil Plait and Pamela Gay. We’ve teamed up with astronomer Mike Phillips who has been livestreaming his telescopes into a Google+ Hangout and then broadcasting it live so everyone can watch. So, it’s sort of like looking through an amazing telescope, but with color commentary from us at the same time.

It’s been an amazing experience so far, but I know it can be even better. I need to find more astronomers able to livestream the view from their telescopes into a webcam and then into a Google+ Hangout. I’d like to have multiple telescopes going at the same time, with different views of the skies. Some focused on planets, others at deep sky objects.

And it doesn’t have to be big telescopes. There are beautiful objects in the sky, like open clusters, which look better with a wider field of view.

So, if you’re interested in participating, you’ll need to have a way to get the view from your telescope, into a webcam, and then use that webcam to join a Google+ Hangout. If you can do that, drop me an email at [email protected] and we’ll run some tests.

Here are two previous nights of experiments that we’ve done so far.

Virtual Star Party – January 6th, 2012

Virtual Star Party – January 5th, 2012

Exomoons? Kepler‘s On The Hunt

An artist impression of an exomoon orbiting an exoplanet, could the exoplanet's wobble help astronomers? (Andy McLatchie)

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Recently, I posted an article on the feasibility of detecting moons around extrasolar planets. It was determined that exceptionally large moons (roughly Earth mass moons or more), may well be detectable with current technology. Taking up that challenge, a team of astronomers led by David Kipping from the Harvard-Smithsonian Center for Astrophysics has announced they will search publicly available Kepler data to determine if the planet-finding mission may have detected such objects.

The team has titled the project “The Hunt of Exomoons with Kepler” or HEK for short. This project searches for moons through two main methods: the transits such moons may cause and the subtle tugs they may have on previously detected planets.

Of course, the possibility of finding such a large moon requires that one be present in the first place. Within our own solar system, there are no examples of moons of the necessary size for detection with present equipment. The only objects we could detect of that size exist independently as planets. But should such objects exist as moons?

Astronomers best simulations of how solar systems form and develop don’t rule it out. Earth sized objects may migrate within forming solar systems only to be captured by a gas giant. If that happens, some of the new “moons” would not survive; their orbits would be unstable, crashing them into the planet or would be ejected again after a short time. But estimates suggest that around 50% of captured moons would survive, and their orbits circularized due to tidal forces. Thus, the potential for such large moons does exist.

The transit method is the most direct for detecting the exomoons. Just as Kepler detects planets passing in front of the disc of the parent star, causing a temporary drop in brightness, so too could it spot a transit of a sufficiently large moon.

The trickier method is finding the more subtle effect of the moon tugging the planet, changing when the transit begins and ends. This method is often known as Timing Transit Variation (TTV) and has also been used to infer the presence of other planets in the system creating similar tugs. Additionally, the same tugs exerted while the planet is crossing the disk of the star will change the duration of the transit. This effect is known as Timing Duration Variations (TDV). The combination of these two variations has the potential to give a great deal of information about potential moons including the moon’s mass, the distance from the planet, and potentially the direction the moon orbits.

Currently, the team is working on coming up with a list of planet systems that Kepler has discovered that they wish to search first. Their criteria are that the systems have sufficient data taken, that it be of high quality, and that the planets be sufficiently large to capture such large moons.

As the team notes

As the HEK project progresses, we hope to answer the question as to whether large moons, possibly even Earth-like habitable moons, are common in the Galaxy or not. Enabled by the equisite photometry of Kepler, exomoons may soon move from theoretical musings to objects of empirical investigation.

Analysis of the First Kepler SETI Observations

Example of signals KOI 817 and KOI 812. Credit: The Search for Extra Terrestrial Intelligence at UC Berkeley

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As the Kepler space telescope begins finding its first Earth-sized exoplanets, with the ultimate goal of finding ones that are actually Earth-like, it would seem natural that the SETI (Search for Extraterrestrial Intelligence) program would take a look at them as well, in the continuing search for alien radio signals. That is exactly what SETI scientists are doing, and they’ve started releasing some of their preliminary results.

They are processing the data taken by Kepler since early 2011; some interesting signals have been found (a candidate signal is referred to as a Kepler Object of Interest or KOI), but as they are quick to point out, these signals so far can all be explained by terrestrial interference. If a single signal comes from multiple positions in the sky, as these ones do, it is most likely to be interference.

They do, however, also share characteristics which would be expected of alien artificial signals.

A couple of examples are from KOI 817 and KOI 812. They are of a very narrow frequency, as would be expected from a signal of artificial origin. They also change in frequency over time, due to the doppler effect – the motion of the alien signal source relative to the radio telescope on Earth. If a signal is found with these characteristics but also does not appear to be just interference, that would be a good candidate for an actual artificial signal of extraterrestrial origin.

These are only the results of the first observations and many more will come during the next weeks and months.

Looking for signals has always been like looking for a needle in the cosmic haystack; until now we were searching pretty much blind, starting even before we knew if there were any other planets out there or not. What if our solar system was the only one? Now we know that it is only one of many, with new estimates of billions of planets in our galaxy alone, based on early Kepler data. Plus the fact that the majority of those are thought to be smaller, rocky worlds like Earth, Mars, etc. How many of them are actually habitable is still an open question, but finding them narrows down the search, providing more probable actual targets to turn the radio telescopes toward instead of just trying to search billions of stars overall.

All twelve signal examples so far can be downloaded here (PDF).

Ask An Astronaut: Mike Fossum

NASA astronaut Mike Fossum onboard the International Space Station during Expedition 28. NASA's Robonaut is also visible in the background. Image credit: NASA TV

[/caption]Following up on our successful “Ask Dr. Alan Stern” interview, we’re continuing our “Ask” series. This time, Universe Today readers will be able to Ask an Astronaut!

Here’s how it works: Readers can submit questions they would like Universe Today to ask the guest responder. Simply post your question in the comments section of this article. We’ll take the top five (or so) questions, as ranked by “likes” on the discussion posts. If you see a question you think is good, click the “like” button to give it a vote.

Keep in mind that final question acceptance is based on the discretion of Universe Today and in some cases, the responder and/or their employer.

This installment features International Space Station Expedition 29 commander, Mike Fossum.

Self-portrait of astronaut Mike Fossum taken on July 8, 2006. Image Credit: NASA / Mike Fossum
Fossum served as an Air Force test pilot until 1992, when he joined NASA. Officially selected for the Astronaut Corps in 1998, His first space flight was on July 4, 2006 as an STS-121 mission specialist.

According to NASA, Fossum completed 167 days in space as a member of the Expedition 28 and 29 crews during his third space flight. Altogether, Fossum has spent 194 days in space and performed seven spacewalks. He ranks seventh on the all-time list for cumulative spacewalking time.

Fossum and his crewmates, Expedition 29 Flight Engineers Sergei Volkov of the Russian Space Agency and Satoshi Furukawa of the Japan Aerospace Exploration Agency, returned to Earth in their Soyuz TMA-02M spacecraft at 8:26 p.m. on Nov. 21, 2011. Fossum was aboard the station during the final space shuttle mission, STS-135, which delivered supplies and equipment to the outpost. During most of his time aboard the ISS, Fossum performed science experiments and routine maintenance.

Before submitting your question, take a minute and read a bit more about Fossum at: http://www.jsc.nasa.gov/Bios/htmlbios/fossum.html

You can also read Fossum’s “Living The Dream” NASA blog at: Mike Fossum’s Blog

We’ll take questions until 6:00PM (MST) Monday, January 9th and provide a follow up article soon after with Fossum’s responses to your questions.

Dazzling Photos of the International Space Station Crossing the Moon!

Moon and International Space Station from NASA Johnson Space Center, Houston, Texas. This photo was taken in the early evening of Jan. 4. Equipment: Nikon D3S, 600mm lens and 2x converter, Heavy Duty Bogen Tripod with sandbag and a trigger cable to minimize camera shake. Camera settings: 1/1600 @ f/8, ISO 2500 on High Continuous Burst. Credit: NASA

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Has the International Space Station (ISS) secretly joined NASA’s newly arrived GRAIL lunar twins orbiting the Moon?

No – but you might think so gazing at these dazzling new images of the Moon and the ISS snapped by a NASA photographer yesterday (Jan. 4) operating from the Johnson Space Center in Houston, Texas.

Check out this remarkable series of NASA photos above and below showing the ISS and her crew of six humans crossing the face of Earth’s Moon above the skies over Houston, Texas. And see my shot below of the Moon near Jupiter – in conjunction- taken just after the two GRAIL spacecraft achieved lunar orbit on New Year’s weekend.

In the photo above, the ISS is visible at the upper left during the early evening of Jan. 4, and almost looks like it’s in orbit around the Moon. In fact the ISS is still circling about 248 miles (391 kilometers) above Earth with the multinational Expedition 30 crew of astronauts and cosmonauts hailing from the US, Russia and Holland.

Space Station Crossing Face of Moon
This composite of images of the International Space Station flying over the Houston area show the progress of the station as it crossed the face of the moon in the early evening of Jan. 4, 2012 over NASA’s Johnson Space Center, Houston, Texas. Credit: NASA
click to enlarge

The amazing photo here is a composite image showing the ISS transiting the Moon’s near side above Houston in the evening hours of Jan 4.

The ISS is the brightest object in the night sky and easily visible to the naked eye if it’s in sight.

With a pair of binoculars, it’s even possible to see some of the stations structure like the solar panels, truss segments and modules.

Check this NASA Website for ISS viewing in your area.

How many of you have witnessed a sighting of the ISS?

It’s a very cool experience !

NASA says that some especially good and long views of the ISS lasting up to 6 minutes may be possible in the central time zone on Friday, Jan 6 – depending on the weather and your location.

And don’t forget to check out the spectacular photos of Comet Lovejoy recently shot by Expedition 30 Commander Dan Burbank aboard the ISS – through the Darth Vader like Cupola dome, and collected here

Moon and International Space Station (at lower right) on Jan 4, 2012 from NASA Johnson Space Center, Houston, Texas. Credit: NASA click to emlarge
Moon, Jupiter and 2 GRAILs on Jan. 2, 2012
Taken near Princeton, NJ after both GRAIL spacecraft achieved lunar orbit after LOI - Lunar Orbit Insertion- burns on New Year’s weekend 2012. Credit: Ken Kremer