Over the past 24 hours, the Sun has erupted with two coronal mass ejections (CMEs), sending billions of tons of solar particles into space. While these CMEs are not directed at Earth, they are heading towards Mercury and may affect the Messenger spacecraft, as well as the Sun-watching STEREO-A satellites. One CME may send a glancing blow of particles to Mars, possibly affecting spacecraft at the Red Planet.
This solar radiation can affect electronic systems on spacecraft, and the various missions have been put on alert. When warranted, NASA operators can put spacecraft into safe mode to protect the instruments from the solar material.
The first CME began at 01:30 UTC on April 25 (9:30 p.m. EDT on April 24), and the second erupted at 09:24 UTC (5:24 a.m. EDT) on April 25. Both left the sun traveling at about 800 kilometers (500 miles per second).
Obtaining an accurate distance between the Sun and the center of our Galaxy remains one of the principal challenges facing astronomers. The ongoing lively debate concerning this distance hinges partly on the nature of dust found along that sight-line. Specifically, are dust particles lying toward the Galactic center different from their counterparts near the Sun? A new study led by David Nataf asserts that, yes, dust located towards the Galactic center is anomalous. They also look at accurately defining both the distance to the Galactic center and the reputed bar structure that encompasses it.
The team argues that characterizing the nature of small dust particles is key to establishing the correct distance to the Galactic center, and such an analysis may mitigate the scatter among published estimates for that distance (shown in the figure below). Nataf et al. 2013 conclude that dust along the sight-line to the Galactic center is anomalous, thus causing a non-standard ‘extinction law‘.
The extinction law describes how dust causes objects to appear fainter as a function of the emitted wavelength of light, and hence relays important information pertaining to the dust properties.
The team notes that, “We estimate a distance to the Galactic center of [26745 light-years] … [adopting a] non-standard [extinction law] thus relieves a major bottleneck in Galactic bulge studies.”
Nataf et al. 2013 likewise notes that, “The variations in both the extinction and the extinction law made it difficult to reliably trace the spatial structure of the [Galactic] bulge.” Thus variations in the extinction law (tied directly to the dust properties) also affect efforts to delineate the Galactic bar, in addition to certain determinations of the distance to the Galactic center. Variations in the extinction law imply inhomogeneities among the dust particles.
“The viewing angle between the bulge’s major axis and the Sun-Galactic centerline of sight remains undetermined, with best values ranging from from 13 to … 44 [degrees],” said Nataf et al. 2013 (see also Table 1 in Vanhollebekke et al. 2009). The team added that, “We measure an upper bound on the tilt of 40 [degrees] between the bulge’s major axis and the Sun-Galactic center line of sight.”
However, the properties of dust found towards the Galactic center are debated, and a spectrum of opinions exist. While Nataf et al. 2013 find that the extinction law is anomalously low, there are studies arguing for a standard extinction law. Incidentally, Nataf et al. 2013 highlight that the extinction law characterizing dust near the Galactic center is similar to that tied to extragalactic supernovae (SNe), “The … [extinction] law toward the inner Galaxy [is] approximately consistent with extra-galactic investigations of the hosts of type Ia SNe.”
Deviations from the standard extinction law, and the importance of characterizing that offset, is also exemplified by studies of the Carina spiral arm. Optical surveys reveal that a prominent spiral arm runs through Carina (although that topic is likewise debated), and recent studies argue that the extinction law for Carina is higher than the standard value (Carraro et al. 2013, Vargas Alvarez et al. 2013). Conversely, Nataf et al. 2013 advocate that dust towards the Galactic center is lower by comparison to the standard (average) extinction law value.
The impact of adopting an anomalously high extinction law for objects located in Carina is conveyed by the case of the famed star cluster Westerlund 2, which is reputed to host some of the Galaxy’s most massive stars. Adopting an anomalous extinction law for Westerlund 2 (Carraro et al. 2013, Vargas Alvarez et al. 2013) forces certain prior distance estimates to decrease by some 50% (however see Dame 2007). That merely emphasizes the sheer importance of characterizing local dust properties when establishing the cosmic distance scale.
In sum, characterizing the properties of small dust particles is important when ascertaining such fundamental quantities like the distance to the Galactic center, delineating the Galactic bar, and employing distance indicators like Type Ia SNe.
If you think that star-formation only has an impact within the confines of a host galaxy, then think again. Thanks to the magic of the NASA/ESA Hubble Space Telescope, astronomers are now realizing starburst activity can change the properties of galactic gases at distances almost twenty times larger than a galaxy’s visible boundaries. Not only does this affect galactic evolution, but it has ramifications on how matter and energy ripple across the cosmos.
What’s going on here? Once upon a time in the early Universe, galaxies would form new stars in huge blasts of activity known as starbursts. While it happened frequently long ago, it’s much less common now. During these starburst episodes, hundreds of millions of stars spring to light and their combined energy sets off massive stellar winds that push outward into space. While these winds were known to have effects on the parent galaxy, new research shows they have an even greater effect than anyone knew.
Recently a team of international astronomers took on twenty galaxies which are known to be hosting starburst activity. What they found was the starburst stellar winds were able to ionize gas at huge distances – up to 650,000 light years from the galaxy’s nucleus – and around twenty times beyond the galaxy’s visible perimeter. For the first time, researchers were able to verify that starburst activity could impact the gas around the parent galaxy. This new observational evidence shows just how important each phase a galaxy goes through can impact the way it form stars and how it evolves.
“The extended material around galaxies is hard to study, as it’s so faint,” says team member Vivienne Wild of the University of St. Andrews. “But it’s important — these envelopes of cool gas hold vital clues about how galaxies grow, process mass and energy, and finally die. We’re exploring a new frontier in galaxy evolution!”
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This animation shows the method used to probe the gas around distant galaxies. Astronomers can use tools such as Hubble’s Cosmic Origins Spectrograph (COS) to probe faint galactic envelopes by exploiting even more distant objects — quasars, the intensely luminous centres of distant galaxies powered by huge black holes. As the light from the distant quasar passes through the galaxy’s halo, the gas absorbs certain frequencies – making it possible to study the region around the galaxy in detail. This new research utilised Hubble’s COS to peer through the very thin outskirts of galactic halos, much further out than shown in this representation, to explore galactic gas at distances of up to twenty times greater than the visible size of the galaxy itself. Credit: ESA, NASA, L. Calçada
So how did they do it? According to the news release, the researchers employed the Cosmic Origins Spectrograph (COS) instrument located on the NASA/ESA Hubble Space telescope. By examining the spectral signature of a variety of starbirth and control galaxies, the team was able to carefully examine the regions of gas surrounding the galaxies. However, they had a little boost, too… quasars. By adding the light of the intensely luminous galactic cores to the mix, they were able to further refine their observations by watching the quasar’s light as it passed through foreground galaxies. This method allowed them to even more closely examine their targets.
“Hubble is the only observatory that can carry out the observations necessary for a study like this,” says lead author Sanchayeeta Borthakur, of Johns Hopkins University. “We needed a space-based telescope to probe the hot gas, and the only instrument capable of measuring the extended envelopes of galaxies is COS.”
The eureka moment came when the astronomers found the starburst galaxies in their samples showed abnormal amounts of highly ionized gases in their halos. By comparison, the control galaxies – those known to have no starburst activity – did not. Now they knew… the ionization had to be the product of the energetic winds which accompanied the birth of new stars. Armed with this information, researchers can now confidently say that galaxies which host starburst activity has taken on new parameters. Since galaxies enlarge by feeding on gas from the space around them and convert this into new stars, we realize that the ionization process will regulate future star formation.
“Starbursts are important phenomena — they not only dictate the future evolution of a single galaxy, but also influence the cycle of matter and energy in the Universe as a whole,” says team member Timothy Heckman, of Johns Hopkins University. “The envelopes of galaxies are the interface between galaxies and the rest of the Universe — and we’re just beginning to fully explore the processes at work within them.”
Astronaut pranks are, well, just a part of the job. Often they poke at a sore spot in the astronaut’s history, and Charles Duke found himself the subject of a particularly painful one in the 1970s.
Duke was in the final moments of preparations before climbing into the Apollo 16 spacecraft, which was exploring the Moon in this week in 1972. It was a serious moment as Duke and his crew were about to rocket off to the moon. Then Duke got a surprise, courtesy of backup commander Fred Haise, as Duke recalled in an interview with NASA in 1999.
We were up climbing into the command module on the launch pad, and [launch pad leader] Guenter Wendt and the team were up there. And so John gets in, and I’m the next in on the right side. And as I start to climb in, I reach in and I look over and taped to the back of my seat was a big thing, “Typhoid Mary suit—seat.” So, we had a … laugh over that. Yeah, Fred would never let me forget that.
Typhoid Mary referred to Mary Mallon, a cook who was put under quarantine for the latter half of her life in the 1900s — against her stringent objections. She was accused of passing along typhoid to several families for which she did cooking, even though she didn’t show any symptoms herself. At the time, typhoid had no cure. Her curious story has been the subject of a PBS show and numerous books.
The joke on Duke hearkened back to the ill-fated Apollo 13 two years before, when Duke’s son caught the German measles. Duke fell ill and unwittingly exposed several astronauts during his contagion period — including the upcoming Apollo 13 prime crew of Jim Lovell, Fred Haise and Ken Mattingly.
Of the three crew members, Mattingly had not been exposed to the German measles. This led to Mattingly being yanked from the mission days before launch. Adding to the drama, Apollo 13 suffered an explosion in space that crippled the spacecraft and, without the extraordinary efforts of the astronauts and Mission Control, could have killed the crew.
Anyway, Apollo 13 came back safely, and in 1972 lessons had been learned from the mission. Haise, to his credit, wasn’t afraid to poke a little fun at the early havoc Duke’s illness wreaked on his crew.
Captured on January 15, this narrow-angle Cassini image shows an outer portion of Saturn’s A ring on the left and the ropy F ring crossing on the right. The thin black line near the A ring’s bright edge is the Keeler Gap, a 22-mile-wide space cleared by the passage of Daphnis, a shepherd moon barely 5 miles (about 7.5 km) across. As it travels around Saturn within the gap its gravity perturbs the fine icy particles within the rings, sending up rippling waves both before and behind it — visible here near the upper center.
From Cassini’s distance of 870,000 miles (1.4 million km) Daphnis itself is just barely visible as a single pixel within the Gap — can you see it? If not, click below…
There it is:
While lacking the murky mystery of Titan’s atmosphere, Enceladus’ dramatic jets and the tortured and cratered surfaces found on Dione, Rhea, Mimas and many of Saturn’s larger icy moons, little Daphnis has always fascinated me because of the scalloped waves it kicks up within Saturn’s rings. Eventually these waves settle back down, but at their highest they can extend a mile or two above and below the ring plane!
This effect was most pronounced during Saturn’s spring equinox in August 2009 when sunlight was striking the rings edge-on, creating strong shadows from any areas of relief.
Imagine the impressive view you’d have if you were nearby, positioned just above the rings as Daphnis approached and hurtled past, the rings rising up in mile-high peaks from the moon’s gravity before smoothing out again. Incredible!
And I’m not the only one to imagine such a scene either — apparently artist Erik Svensson is also intrigued by Daphnis, enough to have been inspired to create the image below. How very cool!
Like its larger shepherd moon sister Prometheus, Daphnis may be little but still has a big effect on the icy stuff that makes up Saturn’s iconic rings.
And for lots more views of Daphnis click here (but watch out, it may just become your favorite moon too!)
Image credits: NASA/JPL-Caltech/Space Science Institute.
Canadian astronaut Chris Hadfield has been called “the internet’s favorite astronaut” and with over 700,000 followers on Twitter, he may be one of the reasons why space is “hot” these days.
A new show featuring Hadfield’s mission on the International Space Station will air on the Canadian Broadcasting Corporation (CBC) on Thursday, April 25 and then will be available world-wide online on April 26.
UPDATE: The online version of this show is now available on CBC here.
CBC’s The Nature of Things is broadcasting “The Man Who Tweeted Earth,”,which looks at Hadfield’s mission and features other astronauts, scientific collaborators, Hadfield’s secret weapon family member (his son) and the Mission Control staff at the Canadian Space Agency and NASA.
Also, Universe Today is proud to say that our own Elizabeth Howell is also part of this broadcast, and she’s event featured on this trailer from the CBC!:
“Essentially, I talk about the techniques Hadfield uses to keep people engaged,” Elizabeth told me, as a teaser for the show. “He tweets about people’s hometowns, for example. I also mentioned the Shatner tweeting incident and how other Star Trek actors reacted. The entire show focuses on Hadfield on the station, the experiments he’s doing, and how folks are reacting to it.”
Elizabeth added that other astronauts and “lots of smart people” are part of the show.
For those of you in Canada (and anyone who otherwise has access to the CBC) the TV broadcast is on Thursday, April 25 at 8 p.m. (8:30 NT) on CBC-TV. There are other re-broadcasts later, so check the CBC’s website for info and to verify the times it is being shown in your time zone.
The show will be available online starting Friday, April 26th at: http://www.cbc.ca/natureofthings/episode/the-man-who-tweeted-earth.html
The Nature of Things is CBC’s flagship science television documentary show and has been broadcasting award-winning shows for more than five decades.
A few years back, when we were all a little younger and less jaded – okay – when I was younger and less jaded (!) Universe Today reviewed the book The Rocket Company. This book speaks to the need of bootstraping our way into funding massive space projects privately, using our own gumption, connections and personalities, and doing so without the help of big governmental organizations because, let’s face it, there is less and less of the proverbial pie to go around.
This fictional book is becoming more lifelike as time goes on with companies like Deep Space Industries, Planetary Resources and many, many others, looking to explore the infinite possibilities our Universe has to offer. On April 30th, this title will be available for free on Amazon.
But for those of you who like the feel and smell of a book in your hands, Patrick Stiennon is giving away 3 free print copies of this book to three lucky Universe Today winners.
This giveaway will run for a week starting today, so get your entries in! How?
In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Wednesday, May 1, 2013. We’ll send you a confirmation email, so you’ll need to click that to be entered into the drawing.
We’re only going to use these email addresses for Universe Today giveaways/contests and announcements. We won’t be using them for any other purpose, and we definitely won’t be selling the addresses to anyone else. Once you’re on the giveaway notification list, you’ll be able to unsubscribe any time you like.
This image almost looks like an artist’s concept, but is an actual photo taken by a camera on board Orbital Science’s Antares rocket showing the Cygnus mass simulator shortly after separation from the rocket’s upper stage.
Antares launched on April 21 for its first test flight – dubbed the A-One mission. The goal of the flight was to test the fully integrated Antares rocket and boost a simulated version of the Cygnus cargo carrier into a target orbit of 250 x 300 kilometers and inclined 51.6 degrees.
Antares also sent a trio of off-the-shelf-smartphone “PhoneSats” to orbit. The three picture-taking satellites are named Alexander, Graham and Bell and are some of the lowest-cost satellites ever flown in space.
Orbital says that both the mass simulator and the upper stage are expected to stay in orbit for several months before their orbits degrade, causing them to re-enter and burn up in the atmosphere.
A test flight of an actual Cygnus capsule is expected later this year, and is currently scheduled for June 2013.
An icy interloper was in the sights of a NASA spacecraft this past weekend.
Comet 2012 F6 Lemmon passed through the field of view of NASA’s HI2A camera as seen from its solar observing STEREO Ahead spacecraft. As seen in the animation above put together by Robert Kaufman, Comet Lemmon is now displaying a fine ion and dust tail as it sweeps back out of the inner solar system on its 10,750 year plus orbit.
Comet Lemmon has been a dependable performer for southern hemisphere observers early in 2013. As we reported earlier this month for Universe Today, this comet is now becoming a binocular object low in the dawn sky for northern hemisphere astronomers.
Comet Lemmon passed perihelion at 0.73 astronomical units from the Sun on March 24th. It’s currently in the +4th to +5 magnitude range as it heads northward through the constellation Pisces.
NASA’s twin Solar TErrestrial RElations Observatory (STEREO) spacecraft often catch sungrazing comets as they observe the Sun. Known as STEREO A (Ahead) & STEREO B (Behind), these observatories are positioned in Earth leading and trailing orbits. This provides researchers with full 360 degree coverage of the Sun. Launched in 2006, STEREO also gives us a unique perspective to spy incoming sungrazing comets. Recently, STEREO also caught Comet 2011 L4 PanSTARRS and the Earth as the pair slid into view.
Another solar observing spacecraft, the European Space Agencies’ SOlar Heliospheric Observatory (SOHO) has been a prolific comet discoverer. Amateur comet sleuths often catch new Kreutz group sungrazers in the act. Thus far, SOHO has discovered over 2400 comets since its launch in 1995. SOHO won’t see PanSTARRS or Lemmon in its LASCO C3 camera but will catch a glimpse of Comet 2012 S1 ISON as it nears the Sun late this coming November.
Like SOHO and NASA’s Solar Dynamics Observatory, data from the twin STEREO spacecraft is available for daily perusal on their website. We first saw this past weekend’s animation of Comet Lemmon passing through STEREO’s field of view on the Yahoo STEREOHunters message board.
Here’s a cool but largely unrecognized fact about comets. As they move back out of the solar system, their dust tail streams out ahead of them, driven by the solar wind. I’ve even seen a few science fiction flicks get this wrong. We simply expect comets to always stream their tails out behind them!
Another observatory in our solar observing arsenal has also moved a little closer to operability recently. The Interface Region Imaging Spectrograph (IRIS) arrived at Vandenberg recently in preparation for launch this summer on June 26th. IRIS will be deployed from a Pegasus XL rocket carried aloft by an L-1011. NuSTAR was launched in a similar fashion in 2012. A Pegasus XL rocket will also launch the TESS exoplanet hunting satellite in 2017.
Keep an eye out for Comet Lemmon as it emerges from the dawn twilight in the days ahead. Also, be sure to post those pics to Universe Today’s Flickr community, and keep tabs on the sungrazing action provided to us by SOHO and STEREO!
While Comet C/2011 L4 (PANSTARRS) is fading to barely naked-eye and binocular visibility (the comet has lost a full magnitude approximately every week since perihelion on March 9), astrophotographers are still able to track down the comet as it moves away from the Sun. This deep color exposure by Chris Schur in Arizona is still able to show surprising detail and Chris said via email that he was “surprised how beautifully colored the stars are in this part of the Milky Way.” Chris’s shot is a 25 minute exposure, and is an LRGB (Luminance, Red, Green and Blue — is a photographic technique used in amateur astronomy for producing good quality color photographs by combining a high-quality black-and-white image with a color image).
See some more recent PANSTARRS images from around the world, below, plus an awesome new timelapse from TWAN (The World At Night) photographer P-M Hedén:
This shot was taken on April 2 when Comet PANSTARRS was snuggling up in the sky with the Andromeda Galaxy, but this beautiful image is a recent addition to Universe Today’s Flickr page. You can see more images of PANSTARRS and the Andromeda Galaxy here and here.
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.