Hubble Archives

November 25, 2014December 23, 2015 by Bob King

Astronomers Discover First Mulitiple-image Gravitationally-lensed Supernova

The four dots around the bright source, an elliptical galaxy, are multiple images of the new supernova taken with the Hubble Space Telescope between November 10-20, 2014. In the bottom image, the galaxy has been digitally removed to show only the supernova. The line segments are diffraction spikes from a nearby star. Credit: P.L. Kelly et. all

How about four supernovae for the price of one? Using the Hubble Space Telescope, Dr. Patrick Kelly of the University of California-Berkeley along with the GLASS (Grism Lens Amplified Survey from Space) and Hubble Frontier Fields teams, discovered a remote supernova lensed into four copies of itself by the powerful gravity of a foreground galaxy cluster. Dubbed SN Refsdal, the object was discovered in the rich galaxy cluster MACS J1149.6+2223 five billion light years from Earth in the constellation Leo. It’s the first multiply-lensed supernova every discovered and one of nature’s most exotic mirages.

The rich galaxy cluster MACS J1149+2223 gained notoriety in 2012 when the most distant galaxy when the most distant galaxy found to date was discovered there through gravitational lensing. — The lensed supernova was discovered far behind the rich galaxy cluster MACS J1149.6+2223. The cluster is one of the most massive known and gained notoriety in 2012 when astronomers harnessed its powerful lensing ability to uncover the most distant galaxy known at the time. Credit: NASA/ESA/M. Postman STScI/CLASH team

Gravitational lensing grew out of Einstein’s Theory of Relativity wherein he predicted massive objects would bend and warp the fabric of spacetime. The more massive the object, the more severe the bending. We can picture this by imagining a child standing on a trampoline, her weight pressing a dimple into the fabric. Replace the child with a 200-pound adult and the surface of the trampoline sags even more.

Massive objects like the sun and even the planets warp the fabric of space. Here a planet orbits the sun but does not fall in because of its sideways orbital motion. — Massive objects like the Sun and even the planets warp the fabric of space. Here a planet orbits the Sun but doesn’t fall in because of its sideways orbital motion.

Similarly, the massive Sun creates a deep, but invisible dimple in the fabric of spacetime. The planets feel this ‘curvature of space’ and literally roll toward the Sun. Only their sideways motion or angular momentum keeps them from falling straight into the solar inferno.

Curved space created by massive objects also bends light rays. Einstein predicted that light from a star passing near the Sun or other massive object would follow this invisible curved spacescape and be deflected from an otherwise straight path. In effect, the object acts as a lens, bending and refocusing the light from the distant source into either a brighter image or multiple and distorted images. Also known as the deflection of starlight, nowadays we call it gravitational lensing.

This illustration shows how gravitational lensing works. The gravity of a large galaxy cluster is so strong, it bends, brightens and distorts the light of distant galaxies behind it. The scale has been greatly exaggerated; in reality, the distant galaxy is much further away and much smaller. Credit: NASA, ESA, L. Calcada

Simulation of distorted spacetime around a massive galaxy cluster over time

Turns out there are lots of these gravitational lenses out there in the form of massive clusters of galaxies. They contain regular matter as well as vast quantities of the still-mysterious dark matter that makes up 96% of the material stuff in the universe. Rich galaxy clusters act like telescopes – their enormous mass and powerful gravity magnify and intensify the light of galaxies billions of light years beyond, making visible what would otherwise never be seen.

Here we see a central slice of the MACS cluster. A massive elliptical galaxy is responsible for splitting SN Refsdal into four images. It also distorts and lenses the purple-toned spiral galaxy that's host to the supernova. Credit: — This cropped image shows the central slice of the MACS J1149 galaxy cluster. A massive elliptical galaxy lenses the light of SN Refsdal into four separate images. It also distorts the purplish spiral galaxy that’s host to the supernova. Credit: NASA/ESA/M. Postman STScI/CLASH team

Let’s return to SN Refsdal, named for Sjur Refsdal, a Norwegian astrophysicist who did early work in the field of gravitational lensing. A massive elliptical galaxy in the MACS J1149 cluster “lenses” the 9.4 billion light year distant supernova and its host spiral galaxy from background obscurity into the limelight. The elliptical’s powerful gravity’s having done a fine job of distorting spacetime to bring the supernova into view also distorts the shape of the host galaxy and splits the supernova into four separate, similarly bright images. To create such neat symmetry, SN Refsdal must be precisely aligned behind the galaxy’s center.

What looks like a galaxy with five nuclei really has just one (at center) surrounded by a mirage of four images of a distant quasar. The galaxy lies 400 million light years away; the quasar about 8 billion. Credit: NASA/ESA/Hubble

The scenario here bears a striking resemblance to Einstein’s Cross, a gravitationally lensed quasar, where the light of a remote quasar has been broken into four images arranged about the foreground lensing galaxy. The quasar images flicker or change in brightness over time as they’re microlensed by the passage of individual stars within the galaxy. Each star acts as a smaller lens within the main lens.

Color-composite image of lensing elliptical galaxy and distorted background host spiral (top).The green circles show the locations of images S1–S4, while another quadruply imaged segment of the spiral arm is marked in red. The bottom panels show two additional lensed images of the spiral host galaxy visible in the galaxy cluster field. Credit: S.L. Kelly et. all — Color-composite image of the lensing elliptical galaxy and distorted background host spiral (top). The green circles, S1-4, show the locations of the supernova images, while another quadruply imaged segment of the spiral arm is marked in red. The bottom panels show two additional lensed images of the spiral host galaxy visible in the galaxy cluster field. Talk about a funhouse mirror! Credit: P.L. Kelly/GLASS/Hubble Frontier Fields

Detailed color images taken by the GLASS and Hubble Frontier Fields groups show the supernova’s host galaxy is also multiply-imaged by the galaxy cluster’s gravity. According to their recent paper, Kelly and team are still working to obtain spectra of the supernova to determine if it resulted from the uncontrolled burning and explosion of a white dwarf star (Type Ia) or the cataclysmic collapse and rebound of a supergiant star that ran out of fuel (Type II).

The time light takes to travel to the Earth from each of the lensed images is different because each follows a slightly different path around the center of the lensing galaxy. Some paths are shorter, some longer. By timing the brightness variations between the individual images the team hopes to provide constraints not only on the distribution of bright matter vs. dark matter in the lensing galaxy and in the cluster but use that information to determine the expansion rate of the universe.

You can squeeze a lot from a cosmic mirage!

November 7, 2014December 23, 2015 by Matt Williams

It’s Complicated: Hubble Survey Finds Unexpected Diversity in Dusty Discs Around Nearby Stars

Images captured by the Hubble Telescope of the vast debris systems surrounding nearby stars. Credit: NASA/ESA/ G. Schneider (University of Arizona), and the HST/GO 12228 Team

Using NASA’s Hubble Space Telescope, astronomers have completed the largest and most sensitive visible-light imaging survey of the debris disks surrounding nearby stars. These dusty disks, likely created by collisions between leftover objects from planet formation, were imaged around stars as young as 10 million years old and as mature as more than 1 billion years old.

The research was conducted by astronomers from NASA’s Goddard Space Center with the help of the University of Arizona’s Steward Observatory. The survey was led by Glenn Schneider, the results of which appeared in the Oct. 1, 2014, issue of The Astronomical Journal.

“We find that the systems are not simply flat with uniform surfaces,” Schneider said. “These are actually pretty complicated three-dimensional debris systems, often with embedded smaller structures. Some of the substructures could be signposts of unseen planets.”

In addition to learning much about the debris fields that surround neighboring stars, the study presented an opportunity to learn more about the formation of our own Solar System.

“It’s like looking back in time to see the kinds of destructive events that once routinely happened in our solar system after the planets formed,” said Schneider.

Once thought to be flat disks, the study revealed an unexpected diversity and complexity of dusty debris structures surrounding the observed stars. This strongly suggest they are being gravitationally affected by unseen planets orbiting the star.

Alternatively, these effects could result from the stars’ passing through interstellar space. In addition, the researchers discovered that no two “disks” of material surrounding stars were alike.

A circumstellar disk of debris around a matured stellar system may indicate that Earth-like planets lie within. Credit: NASA/JPL — *A circumstellar disk of debris around a matured stellar system may indicate that Earth-like planets lie within.* *Credit: NASA/JPL*

The astronomers used Hubble’s Space Telescope Imaging Spectrograph to study 10 previously discovered circumstellar debris systems, plus MP Mus, a mature protoplanetary disk that is comparable in age to the youngest of the debris disks.

Irregularities observed in one ring-like system in particular (around HD 181327) resemble the ejection of a huge spray of debris into the outer part of the system from the recent collision of two bodies.

“This spray of material is fairly distant from its host star — roughly twice the distance that Pluto is from the Sun,” said co-investigator Christopher Stark of NASA’s Goddard Space Flight Center, Greenbelt, Maryland. “Catastrophically destroying an object that massive at such a large distance is difficult to explain, and it should be very rare. If we are in fact seeing the recent aftermath of a massive collision, the unseen planetary system may be quite chaotic.”

Another interpretation for the irregularities is that the disk has been mysteriously warped by the star’s passage through interstellar space, directly interacting with unseen interstellar material. “Either way, the answer is exciting,” Schneider said. “Our team is currently analyzing follow-up observations that will help reveal the true cause of the irregularity.”

Over the past few years astronomers have found an incredible diversity in the architecture of exoplanetary systems. For instance, they have found that planets are arranged in orbits that are markedly different than found in our solar system.

A collision between planets could be the reason for the debris field around HD 181327. Credit: NASA/JPL-Caltech — *A collision between two bodies is one explanation for the ring-like debris system around HD 181327. Credit: NASA/JPL-Caltech*

“We are now seeing a similar diversity in the architecture of accompanying debris systems,” Schneider said. “How are the planets affecting the disks, and how are the disks affecting the planets? There is some sort of interdependence between a planet and the accompanying debris that might affect the evolution of these exoplanetary debris systems.”

From this small sample, the most important message to take away is one of diversity, Schneider said. He added that astronomers really need to understand the internal and external influences on these systems – such as stellar winds and interactions with clouds of interstellar material – and how they are influenced by the mass and age of the parent star, and the abundance of heavier elements needed to build planets.

Though astronomers have found nearly 4,000 exoplanet candidates since 1995, mostly by indirect detection methods, only about two dozen light-scattering, circumstellar debris systems have been imaged over that same time period.

That’s because the disks are typically 100,000 times fainter than (and often very close to) their bright parent stars. The majority have been seen because of Hubble’s ability to perform high-contrast imaging, in which the overwhelming light from the star is blocked to reveal the faint disk that surrounds the star.

The new imaging survey also yields insight into how our solar system formed and evolved 4.6 billion years ago. In particular, the suspected planet collision seen in the disk around HD 181327 may be similar to how the Earth-Moon system formed, as well as the Pluto-Charon system over 4 billion years ago. In those cases, collisions between planet-sized bodies cast debris that then coalesced into a companion moon.

Further Reading: The Hubble Site

October 28, 2014January 15, 2019 by Matt Williams

Just In Time for Halloween: Jupiter Gets a Giant Cyclops Eye!

Jupiter's Great Red Spot and Ganymede's Shadow. Image Credit: NASA/ESA/A. Simon (Goddard Space Flight Center)

Halloween is just around the corner. And in what appears to be an act of cosmic convergence, Hubble captured a spooky image of Jupiter staring back at us with a cyclops eye!

While this is merely a convenient illusion caused by the passage of Ganymede in front of Jupiter – something it does on a regular basis – the timing and appearance are perfect.

Continue reading “Just In Time for Halloween: Jupiter Gets a Giant Cyclops Eye!”

October 24, 2014December 23, 2015 by Tim Reyes

Making Cubesats do Astronomy

Will cubesats develop a new technological branch of astronomy? Goddard engineers are taking the necessary steps to make cubesat sized telescopes a reality. (Credit: NASA, UniverseToday/TRR)

One doesn’t take two cubesats and rub them together to make static electricity. Rather, you send them on a brief space voyage to low-earth orbit (LEO) and space them apart some distance and voilà, you have a telescope. That is the plan of NASA’s Goddard Space Flight Center engineers and also what has been imagined by several others.

Cubesats are one of the big crazes in the new space industry. But nearly all that have flown to-date are simple rudderless cubes taking photos when they are oriented correctly. The GSFC engineers are planning to give two cubes substantial control of their positions relative to each other and to the Universe surrounding them. With one holding a telescope and the other a disk to blot out the bright sun, their cubesat telescope will do what not even the Hubble Space Telescope is capable of and for far less money.

Semper (left), Calhoun, and Shah are advancing the technologies needed to create a virtual telescope that they plan to demonstrate on two CubeSats. (Image/Caption Credit: NASA/W. Hrybyk)

The 1U, the 3U, the 9U – these are all cubesats of different sizes. They all have in common the unit size of 1. A 1U cubesat is 10 x 10 x 10 centimeters cubed. A cube of this size will hold one liter of water (about one quart) which is one kilogram by weight. Or replace that water with hydrazine and you have very close to 1 kilogram of mono-propellent rocket fuel which can take a cubestat places.

GSFC aerospace engineers, led by Neerav Shah, don’t want to go far, they just want to look at things far away using two cubesats. Their design will use one as a telescope – some optics and a good detector –and the other cubesat will stand off about 20 meters, as they plan, and function as a coronagraph. The coronagraph cubesat will function as a sun mask, an occulting disk to block out the bright rays from the surface of the Sun so that the cubesat telescope can look with high resolution at the corona and the edge of the Sun. To these engineers, the challenge is keeping the two cubesats accurately aligned and pointing at their target.

Only dedicated Sun observing space telescopes such as SDO, STEREO and SOHO are capable of blocking out the Sun, but their coronagraphs are limited. Separating the coronagraph farther from the optics markedly improves how closely one can look at the edge of a bright object. With the corongraph mask closer to the optics, more bright light will still reach the optics and detectors and flood out what you really want to see. The technology Shah and his colleagues develop can be a pathfinder for future space telescopes that will search for distant planets around other stars – also using a coronagraph to reveal the otherwise hidden planets.

The engineers have received a $8.6-million investment from the Defense Advanced Research Project Agency (DARPA) and are working in collaboration with the Maryland-based Emergent Space Technologies.

An example of a 3U cubesat - 3 1U cubes stacked. This cubesat size could function as the telescope of a two cubesat telescope system. It could be a simple 10 cm diameter optic system or use fancier folding optics to improve its resolving power. (Credit: LLNL) — An example of a 3U cubesat – 3 1U cubes stacked. This cubesat size could function as the telescope of a two cubesat telescope system. It could be a simple 10 cm diameter optic system or use fancier folding optics to improve its resolving power. (Credit: LLNL)

The challenge of GSFC engineers is giving two small cubesats guidance, navigation, and control (GN&C) as good as any standard spacecraft that has flown. They plan on using off-the-shelf technology and there are many small and even large companies developing and selling cubesat parts.

This is a sorting out period for the cubesat sector, if you will, of the new space industry. Sorting through the off-the-shelf components, the GSFC engineers led by Shah will pick the best in class. The parts they need are things like tiny sun sensors and star sensors, laser beams and tiny detectors of those beams, accelerometers, tiny gyroscopes or momentum wheels and also small propulsion systems. The cubesat industry is pretty close to having all these ready as standard issue. The question then is what do you do with tiny satellites in low-Earth orbit (LEO). Telescopes for earth-observing are already making headway and scopes for astronomy are next. There are also plans to venture out to interplanetary space with tiny and capable cubesat space probes.

Whether one can sustain a profit for a company built on cubesats remains a big question. Right now those building cubesats to customer specs are making a profit and those making the tiny picks and shovels for cubesats are making profits. The little industry may be overbuilt which in economic parlance might be only natural. Many small startups will fail. However, for researchers at universities and research organizations like NASA, cubesats have staying power because they reduce cost by their low mass and size, and the low cost of the components to make them function. The GSFC effort will determine how quickly cubesats begin to do real work in the field of astronomy. Controlling attitude and adding propulsion is the next big thing in cubesat development.

References:

NASA Press Release

October 23, 2014December 23, 2015 by Elizabeth Howell

Hubble Composite Picture Shows How Close Siding Spring Comet Was To Mars

Comet Siding Spring near Mars in a composite image by the Hubble Space Telescope, capturing their positions between Oct. 18 8:06 a.m. EDT (12:06 p.m. UTC) and Oct. 19 11:17 p.m. EDT (Oct. 20, 3:17 a.m. UTC). Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA

We’ve seen spectacular images of Comet Siding Spring from Mars spacecraft, showing just how close the small body was to the Red Planet when it whizzed by Sunday (Oct. 19). But how close were the two objects actually, in the sky? This Hubble Space Telescope composite image shows just how astoundingly near they were.

Above are two separate exposures taken Oct. 18-19 EDT (Oct. 18-20 UTC) against the same starry field image from another survey. It was a complicated shot to get, NASA explains, but it does serve as a powerful illustration of the celestial close encounter.

“This is a composite image because a single exposure of the stellar background, comet Siding Spring, and Mars would be problematic. Mars is actually 10,000 times brighter than the comet, and so could not be properly exposed to show detail in the Red Planet,” NASA stated.

High resolution image pairs made with HiRISE camera on MRO during Comet Siding Spring's closest approach to Mars on October 19. Shown at top are images of the nucleus region and inner coma. Those at bottom were exposed to show the bigger coma beginning of a tail. Credit: NASA/JPL/Univ. of Arizona — High resolution image pairs made with HiRISE camera on MRO during Comet Siding Spring’s closest approach to Mars on October 19. Shown at top are images of the nucleus region and inner coma. Those at bottom were exposed to show the bigger coma beginning of a tail. Credit: NASA/JPL/Univ. of Arizona

“The comet and Mars were also moving with respect to each other and so could not be imaged simultaneously in one exposure without one of the objects being motion blurred. Hubble had to be programmed to track on the comet and Mars separately in two different observations.”

The two images were blended together in this single shot, showing their separation of 1.5 arc minutes (1/20 of the Moon’s apparent diameter.) The background stars comes from data from the Palomar Digital Sky Survey “reprocessed to approximate Hubble’s resolution”, NASA stated.

While the nucleus is too small to be imaged by Hubble, you can see what it looks like in the image above from the Mars Reconnaissance Orbiter. Siding Spring passed by the Red Planet at a distance of just 87,000 miles (140,000 km).

Source: NASA

October 16, 2014December 23, 2015 by Elizabeth Howell

Pluto Planning: Hubble Spots 3 Objects NASA Spacecraft Could Visit Next

Two potential targets for the New Horizons mission emerge in these Hubble Space Telescope multiple-exposure images. Both are about four billion miles (6.4 billion kilometers) away. NASA, ESA, SwRI, JHU/APL, and the New Horizons KBO Search Team

Where could New Horizons visit after it flies by Pluto next year? NASA’s Hubble Space Telescope is on the case. In a program that pushed the limits of the 24-year-old observatory, Hubble found three potential Kuiper Belt Objects for the spacecraft to visit.

The wrinkle is there is no money approved yet for New Horizons to do an extended mission yet, but team members (including Alex Parker from the Southwest Research Institute, who is quoted from Twitter below) are celebrating the milestone. To them, the most promising target (PT1) is the one on the left of the images you see above. Read more about it below the jump.

The Kuiper Belt is a zone of icy objects about four billion miles (6.4 billion kilometers) from the Sun, considered to be leftovers of the building blocks that put together the Solar System billions of years ago. It’s an area that Pluto itself drifts through from time to time on its elliptical orbit around the Sun. Roughly 1,000 objects there have been cataloged, although many more are believed to exist.

The team used Hubble from June 16 to 26 in a test program to look at 20 sky zones for evidence of KBOs, finding two that had never been spotted before by ground-based telescopes. More searching between July and September revealed one object that is “definitely reachable”, NASA stated, and two others that require more scrutiny.

We estimate that PT1 is several 10s of kilometers across. Here’s what that looks like next to Cape Cod and #Comet67P: pic.twitter.com/IHUx6uymO7

— Alex Parker (@Alex_Parker) October 15, 2014

Here is where PT1 lies in relation to the rest of the solar system. The yellow path is New Horizons’ trajectory. pic.twitter.com/4aQDEj8oPZ — Alex Parker (@Alex_Parker) October 15, 2014

Here is a gif of the Hubble Space Telescope discovery images of our New Horizons-targetable Kuiper Belt Object PT1. http://t.co/ifw8I4a8Wz

— Alex Parker (@Alex_Parker) October 15, 2014

An important and sobering note: even though New Horizons can reach this Kuiper Belt Object, there is no guarantee of an extended mission. — Alex Parker (@Alex_Parker) October 15, 2014

Each of the three candidates would take a while to reach, as they are all about one billion miles (1.6 billion km) beyond Pluto. They’re also tiny, with two estimated at 34 miles (55 kilometers) across and the third at 15 miles (25 kilometers). This makes them 10 times bigger than the average comet, but only 1-2% the size of small Pluto.

“This was a needle-in-haystack search for the New Horizons team because the elusive KBOs are extremely small, faint, and difficult to pick out against a myriad background of stars in the constellation Sagittarius, which is in the present direction of Pluto,” NASA wrote in a press release.

New Horizons’ team plans to ask for the extended mission in late 2016. Meanwhile, the spacecraft (which has been flying ever outwards since 2006) will finally zoom past its main target of Pluto in July 2015.

September 25, 2014December 23, 2015 by Tammy Plotner

Hubble Vision: Galaxy DDO 68 – Young Or Old?

Only astronomers know for sure… Or do they? In this assembly of images taken with Hubble’s Advanced Camera for Surveys, scientists have utilized both visible and infrared light to survey a most unusual galaxy. When looking for a newly formed galaxy in our “cosmic neighborhood”, they spied DDO 68 (a.k.a. UGC 5340). Normally to witness galactic evolution, we have to look over great distances to see back in time… but this particular collection of gas and stars seems to break the rules!

Researching galactic evolution isn’t a new concept. Over the last few decades astronomers have increased our understanding of how galaxies change with time. One of the most crucial players in this game has been the NASA/ESA Hubble Space Telescope. Through its eyes, scientists can see over almost incomprehensible distances – studying light that has taken billions of years to reach us. We are essentially looking back in time.

While this is great news on its own, studying progressively younger galaxies can sometimes pose more questions than it answers. For example, all the newly created galaxies reside a huge distance from us and thereby appear small and faint when imaged. On the other side of the coin, galaxies which are close to us appear to be far more mature.

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This video begins with a ground based view of the night sky, before zooming in on dwarf galaxy DDO 68 as the NASA/ESA Hubble Space Telescope sees it. This ragged collection of stars and gas clouds looks at first glance like a recently-formed galaxy in our own cosmic neighbourhood. But, is it really as young as it looks? Credit: NASA/ESA

DDO 68, imaged here by the NASA/ESA Hubble Space Telescope, would seem to be the best example of a nearby newly-formed galaxy. Just how nearby? Estimates place it at about 39 million light years distant. While this might seem like a very long way, it is still roughly 50 times closer than other galactic examples. Studying galaxies of different ages is important to our understanding of how the Universe works. Astronomers have discovered that young galaxies are quite different than those which have aged. In this case, DDO 68 gives off the appearance of being young. These findings come from examining its structure, appearance and composition. However, researchers question their findings. It is possible this galaxy may be considerably older than initial findings indicate.

“All of the available data are consistent with the fact that DDO 68 is a very rare candidate for young galaxies.” says S. A. Pustilnik (et al). “The bulk of its stars were formed during the recent (with the first encounter about 1 Gyr ago) merger of two very gas-rich disks.”

These common events – mergers and collisions – are part of galactic life and are generally responsible for older galaxies being more bulky. These “senior citizens” are normally laced with a wide variety of stellar types – young, old, large and small. The chemistry is also different, too. Very young galaxies are rich in hydrogen and helium, making them tantalizingly similar in composition to the primordial matter created by the Big Bang. Older galaxies have more experiences. Numerous stellar events have happened within them over their lifetimes, making them rich in heavy elements. This is what makes DDO 68 very exciting! It is the best local candidate found so far to be low in heavier elements.

“DDO 68 (UGC 5340) is the second most metal-poor star-forming galaxy,” explains Pustilnik. “Its peculiar optical morphology and its HI distribution and kinematics are indicative of a merger origin. We use the u, g, r, and i photometry based on the SDSS images of DDO 68 to estimate its stellar population ages.”

Step into the light? You bet. The Hubble observations were meant to examine the properties of this mysterious galaxy’s light – determine whether or not it contains any older stars. If they are discovered, which seems to be the case, this would disprove the theory that DDO 68 is singularly comprised of younger stars. If not, it will validate the unique nature of this nearby neighbor. While more computer modeling and studies are needed, we can still enjoy this incredible look at another cosmic enigma!

Original Story Source: A Galaxy Of Deception – Hubble/ESA

September 25, 2014December 23, 2015 by Elizabeth Howell

Alien Planet’s Clear Weather Could Show Way To ‘Super-Earth’ Atmospheres

Artist's concdption of a Neptune-sized planet with a clear atmosphere, passing across the face of its star. Credit: NASA/JPL-Caltech

In an encouraging find for habitability researchers, astronomers have detected molecules on the smallest planet ever — a Neptune-sized planet about 120 light-years from Earth. The team behind the discovery says this means the dream of understanding the atmospheres on planets even closer to size of Earth is getting closer.

“The work we are doing now is important for future studies of super-Earths and even smaller planets, because we want to be able to pick out in advance the planets with clear atmospheres that will let us detect molecules,” stated co-author Heather Knutson, of the California Institute of Technology.

This particular world is not life-friendly as we understand it, however. Called HAT-P-11b, it’s not only a gas giant but also a planet that orbits extremely close to its star — making one circle every five days. And unusually among planets of its size that were previously probed by astronomers, it appears to have clear skies.

The team examined the world using the Hubble Space Telescope’s Wide Field Camera 3, looking at the planet as it passed across the face of its star. The team compared the signature of elements observed when the planet was in front of the star and when it was not, and discovered telltale signs of water vapor in its atmosphere.

Artist's conception of what the weather may look like on HAT-P-11b, a Neptune-sized exoplanet. The upper atmosphere (right) appears clear while the lower atmosphere may host clouds. Credit: NASA/JPL-Caltech — Artist’s conception of what the weather may look like on HAT-P-11b, a Neptune-sized exoplanet. The upper atmosphere (right) appears clear while the lower atmosphere may host clouds. Credit: NASA/JPL-Caltech

While other planets outside our solar system are known to have water vapor, the ones previously examined are much larger. Jupiter-sized planets are much easier to examine not only because they are larger, but their atmospheres puff up more (making them more visible from Earth.)

To confirm the water vapor was not a false signal from sunspots on the parent star (which also can contain it), the team used the Kepler and Spitzer space telescopes to confirm the information. (Kepler’s single field of view around the constellation Cygnus, which it had been peering at for about four years, happily included the zone where HAT-P-11b was orbiting.) The infrared information from Spitzer and the visible-light data from Kepler both showed the sunspots were too hot for water vapor.

Further, the discovery shows there were no clouds in the way of the observations — a first for planets of that size. The team also hopes that super-Earths could have clear skies, allowing astronomers to analyze their atmospheres.

“When astronomers go observing at night with telescopes, they say ‘clear skies’ to mean good luck,” stated lead author Jonathan Fraine, of the University of Maryland, College Park. “In this case, we found clear skies on a distant planet. That’s lucky for us because it means clouds didn’t block our view of water molecules.”

The research was published in the journal Nature.

Source: NASA

August 14, 2014December 23, 2015 by Elizabeth Howell

Diamond Pinpricks: Gorgeous Shot Of Star Group That Once Baffled Astronomers

A Hubble Space Telecope picture of globular cluster IC 4499. The new observations showed that it is about 12 billion years old, contrary to previous observations showing a puzzling young age. Credit: European Space Agency and NASA

Is this group of stars belonging to one generation, or more? That’s one of the things that was puzzling astronomers for decades, particularly when they were trying to pin down the age of IC 4499 — the globular cluster you see in this new picture from the Hubble Space Telescope.

While astronomers now know the stars are from a single generation that are about 12 billion years old (see this paper from three years ago), for about 15 years before that at least one paper said IC 4499 was three billion to four billion years younger than that.

“It has long been believed that all the stars within a globular cluster form at the about same time, a property which can be used to determine the cluster’s age,” stated information from the European Space Agency reposted on NASA’s website.

“For more massive globulars however, detailed observations have shown that this is not entirely true — there is evidence that they instead consist of multiple populations of stars born at different times.”

IC 4499 is somewhere in between these extremes, but only has a single generation of stars — its gravity wasn’t quite enough to pull in neighboring gas and dust to create more. Goes to show you how important it is to re-examine the results in science.

Source: NASA and the European Space Agency

August 6, 2014December 23, 2015 by Shannon Hall

Hubble Archive Reveals Possible Culprit for Enigmatic Supernova

The white X at the top of the image marks the location of the supernova. The inset panel is a pair of Hubble Space Telescope images of the spiral galaxy NGC 1309 that were taken before and after the appearance of Supernova 2012Z. Credit: NASA, ESA, C. McCully and S. Jha (Rutgers University), R. Foley (University of Illinois), and Z. Levay (STScI)

More than two decades of Hubble observations have produced more than 25 terabytes of data. Thanks to the wealth of information stored in the Hubble data archive, astronomers can easily revisit old images in an effort to better understand new discoveries.

Now, astronomers have used the archive to find the progenitor of a mysterious type of supernova, dubbed Type 1ax, which is less energetic and much fainter than its Type Ia cousin.

A Type 1a supernova occurs when a white dwarf siphons material off a companion star, building an additional layer of hydrogen on its surface that will eventually trigger a runaway reaction that detonates the accumulated gas.

The most popular explanation for Type 1ax supernovae is that they’re created in the same way, except the explosion doesn’t completely tear the white dwarf into pieces. Instead, the white dwarf ejects roughly half of its mass. It becomes battered and bruised, leaving behind a hot core composed of carbon and oxygen.

So far, astronomers have identified more than 30 of these mini-explosions, which occur at one-fifth the rate of Type 1a supernovae.

“Astronomers have been searching for decades for the progenitors of Type Ia’s,” said Saurabh Jha from Rutgers University in a NASA press release. “Type Ia’s are important because they’re used to measure vast cosmic distances and the expansion of the universe. But we have very few constraints on how any white dwarf explodes. The similarities between Type Iax’s and normal Type Ia’s make understanding Type Iax progenitors important, especially because no Type Ia progenitor has been conclusively identified.”

So after the team observed the weak supernova, dubbed SN 2012Z, in the Lick Observatory Supernova Search, they dug through Hubble’s archive. Fortuitously, Hubble had observed the supernova’s host galaxy, NGC 1309, in 2005, 2006, and 2010, before the supernova outburst.

Curtis McCully, a graduate student at Rutgers and lead author on the team’s paper, reprocessed the pre-explosion images to find an object at the supernova’s position.

“I was very surprised to see anything at the supernova’s location,” said McCully. “We expected that the progenitor system would be too faint to see, like in previous searches for normal Type Ia supernova progenitors. It is exciting when nature surprises us.”

The pre-supernova observations reveal a bright, blue source the team calls S1. McCully and colleagues concluded that they were most likely seeing a star that had lost its outer hydrogen envelope, revealing its helium core. But they don’t think it’s a type of star that was about to explode, rather it’s the companion that fed the white dwarf’s outburst.

The most likely explanation involves a binary star system where each star detonates mass to the other over time.

The team acknowledges that they can’t totally rule out other possibilities for the object’s identity, including that it was simply a single, massive star that exploded as a supernova. To settle any uncertainties the team plans to use Hubble again in 2015. Hopefully by then the supernova should fade enough to get a better look at what remains.

The team’s results will appear in the journal Nature tomorrow.