Artist's conception of a starquake cracking the surface of a neutron star. Credit: Darlene McElroy of LANL
Much like how an earthquake can teach us about the interior of the Earth, a starquake shows off certain properties about the inside of a star. Studying the closest star we have (the sun) has yielded information about rotation, radius, mass and other properties of stars that are similar to our own. But how do we apply that information to other types of stars?
A team of astronomers attempted to model the inside of a delta-Scuti, a star like Caleum that is about 1.5 to 2.5 times the mass of the sun and spins rapidly, so much more that it tends to flatten out. The model reveals there is likely a correlation between how these types of stars oscillate, and what their average density is. The theory likely holds for stars as massive as four times the mass of our sun, the team said.
“Thanks to asteroseismology we know precisely the internal structure, mass, radius, rotation and evolution of solar type stars, but we had never been able to apply this tool efficiently to the study of hotter and more massive stars,” stated Juan Carlos Suárez, a researcher at the Institute of Astrophysics of Andalusia who led the investigation.
Model of an oscillation within the sun. Credit: David Guenther, Saint Mary´s University
What’s more, knowing how dense a star is leads to other understandings: what its mass is, its diameter and also the age of any exoplanets that happen to be hovering nearby. The astronomers added that the models could be of use for the newly selected Planetary Transits and Oscillations (PLATO) telescope that is expected to launch in 2024.
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.
A newly-discovered star of magnitude +10.9 has flared to life in the constellation Cygnus the Swan. Koichi Nishiyama and Fujio Kabashima, both of Japan, made their discovery yesterday March 31 with a 105mm f/4 camera lens and electronic camera. They quickly confirmed the observation with additional photos taken with a 0.40-m (16-inch) reflector. Nothing was seen down to magnitude +13.4 in photos taken the on the 27th, but when they checked through images made on March 30 the star present at +12.4. Good news – it’s getting brighter!
This more detailed map, showing stars to mag. 10.5, will help you pinpoint the star. Its coordinates are R.A. 20h 21m 42, declination +31 o3′. Stellarium
While the possible nova will need confirmation, nova lovers may want to begin observing the star as soon as possible. Novae can brighten quickly, sometimes by several magnitudes in just a day. These maps should help you hone in on the star which rises around midnight and becomes well placed for viewing around 1:30-2 a.m. local time in the eastern sky. At the moment, it will require a 4-inch or larger telescope to see, but I’m crossing my fingers we’ll see it brighten further.
Novae occur in close binary systems where one star is a tiny but extremely compact white dwarf star. The dwarf pulls material into a disk around itself, some of which is funneled to the surface and ignites in a nova explosion. Credit: NASA
To see a nova is to witness a cataclysm. Astronomers – mostly amateurs – discover about 10 a year in our Milky Way galaxy. Many more would be seen were it not for dust clouds and distance. All involve close binary stars where a tiny but extremely dense white dwarfstar steals gas from its companion. The gas ultimately funnels down to the 150,000 degree surface of the dwarf where it’s compacted by gravity and heated to high temperature until it ignites in an explosive fireball. If you’ve ever wondered what a million nuclear warheads would look like detonated all at once, cast your gaze at a nova.
Novae can rise in brightness from 7 to 16 magnitudes, the equivalent of 50,000 to 100,000 times brighter than the sun, in just a few days. Meanwhile the gas they expel in the blast travels away from the binary at up to 2,000 miles per second.
Emission of deep red light called hydrogen alpha or H-alpha is often diagnostic of a nova. When in the fireball phase, the star is hidden by a fiery cloud of rosy hydrogen gas and expanding debris cloud. Italian astronomer obtained this spectrum of the possible nova on April 1 showing H-alpha emission. Credit: Gianluca Masi
Nishiyama and Kabashima are on something of a hot streak. If confirmed, this would be their third nova discovery in a month! On March 8, they discovered Nova Cephei 2014 at magnitude 11.7 (it’s currently around 12th magnitude) and 10th magnitude Nova Scorpii 2014 (now at around 12.5) on March 26. Impressive.
Photo showing the possible nova in Cygnus. The star is described as being tinted red. Credit: Gianluca Masi
Charts for the two older discoveries are available on the AAVSO website. Type in either Nova Cep 2014 or TCP J17154683-3128303 (for Nova Scorpii) in the Star finder box and click Create a finder chart. I’ll update this article as soon as a chart for the new object is posted.
** UPDATE April 2, 2014: This star has been confirmed as a nova. You can print out a chart by going to the AAVSO website and following the instructions above using Nova Cyg 2014 for the star name. On April 2.4 UT, I observed the nova at magnitude 11.o.
When the United States helped defeat Germany at the end of World War II, they acquired the German rocket scientist Wernher von Braun. He had already developed the German V2 rocket program, and went on to design all the major hardware of the US rocket program. This week, we talk about von Braun’s life and accomplishments.
This will be the 6th year that the Virtual Telescope Project has on an online Messier Marathon, and they’ll be using their robotic telescopes, providing real time images — all while chatting and sharing the passion and excitement with people from around the world.
Pamela has a day job, remember? As an astronomer? Recently the 45th Lunar and Planetary Science Conference occurred in the The Woodlands, Texas. Pamela and guest astronomer Sondy Springmann will let us know about the big announcements made at this year’s conference.?
The Kavir desert in Iran, as seen from the International Space Station on Feb. 14, 2014. Credit: NASA.
At first glance, this beautiful swirling view appears like clouds above a large body of water or possibly the eddies of ocean currents. Surprisingly, this is a desert, the Kavir desert (Dasht-e Kavir – literally ‘desert of salt-marsh’) in Iran, and the image was taken by one of the astronauts on the International Space Station.
An annotated version of the image of the Kavir Desert. Credit: NASA
You’ll notice the striking pattern of parallel lines and sweeping curves. NASA explains that the lack of soil and vegetation in this desert allows the geological structure of the rocks to appear quite clearly from space and the patterns result from the gentle folding of numerous, thin layers of rock. “Later erosion by wind and water cut a flat surface across the dark- and light-colored folds, not only exposing hundreds of layers but also showing the shapes of the folds. The pattern has been likened to the layers of a sliced onion,” NASA says.
While a quick look at Google Maps (see image below) shows that most of the region does appear to be sand-colored brown from space, there are regions with blue tints due to the folds and layers in the exposed surfaces, and the image is actually just a small part of the 77,600 square kilometer (30,000 sq mile) desert. It’s a bit difficult to get a sense of scale in the top image since there are no fields or roads to provide a reference, but the width of the image is about 105 kilometers (65 miles).
There is some water in this area, however. In the center of the NASA image is a dark s-shaped region is a lake and a small river snakes across the bottom of the image. The irregular, light-toned patch just left of the lake is a sand sheet thin enough to allow the underlying rock layers to be detected.
Screenshot of Google Maps showing the Kavir Desert in Iran.
Astronaut Piers Sellers during an STS-121 spacewalk in 2006 to demonstrate techniques on repairing the shuttle's heat shield. Credit: NASA
Could a long mission to Mars increase your risk of heart problems back on Earth? That’s something that scientists are trying to better understand after discovering that hearts become temporarily rounder in space, at least in a study of 12 astronauts.
The finding doesn’t appear to be a big surprise for cardiovascular scientists, however, who had the astronauts examine their hearts using ultrasound machines on the International Space Station as well as before and after spaceflight. The heart gets 9.4 percent more round, similar to models developed for the project, before returning to its normal shape on Earth.
“The heart doesn’t work as hard in space, which can cause a loss of muscle mass,” stated James Thomas, lead scientist for ultrasound at NASA, and senior author of the study. “That can have serious consequences after the return to Earth, so we’re looking into whether there are measures that can be taken to prevent or counteract that loss.”
Astronauts typically spend six months on the International Space Station. One year from now, NASA’s Scott Kelly and Roscomos’ Mikhail Kornienko are going to launch for a one-year mission. Spending months upon months in space leads to a host of problems upon returning to Earth. Your muscles get weaker, you’re more likely to pass out, and you’re at increased risk of bone fractures, among other problems.
NASA astronaut Norm Thagard exercises aboard the Russian Mir space station in 1995. Thagard was the first American to launch into space aboard a Soyuz and spent what was then a record-breaking 115 days in space. Credit: NASA
A typical person on the space station spends two hours a day exercising just to ward off the worst of the effects. The researchers added that one remedy could be to add more exercises targeting the heart. This will be particularly important for missions that last 12 to 18 months or more — such as a Mars mission.
Studying astronauts in space could provide data on Earth-bound patients facing similar problems, the researchers said. Since the models that they made for astronauts were so congruent with reality, this gives the researchers confidence that they could create similar models for patients on Earth.
Conditions that could be considered include ischemic heart disease (the most common kind of heart disease and source of heart attacks), hypertrophic cardiomyopathy (thickened heart muscle) and valvular heart disease (damage to one of the heart’s valves).
Results were presented last week at the American College of Cardiology’s annual conference. It’s not immediately clear from a press release if the study was peer-reviewed. The researchers added that more study of astronauts after returning to Earth could be a useful research direction, to see how the effects persist (if at all.)
A photogenic grouping greets evening sky watchers this week providing a fine teaser leading up to a spectacular eclipse.
On the evening of Thursday, April 3rd headed into the morning of the 4th, the waxing crescent Moon crosses in front of the Hyades open star cluster. This is the V-shaped asterism that marks the head on Taurus the Bull, highlighted by the brilliant foreground star Aldebaran as the bull’s “eye”. Viewers across North America will have a ring-side seat to this “bull-fight” as the 20% illuminated Moon stampedes over several members of the Hyades in its path.
The passage of the Moon through the Hyades over a three hour span on the night of April 3rd (April 4th in Universal Time) comparing the North American locales of Tampa, Florida and Seattle, Washington. (Credit: Starry Night Education Software).
The brightest stars to be occulted are the Delta Tauri trio of stars ranging in magnitudes from +3.8 (Delta Tauri^1) to +4.8(2) and +4.3(3). Such occlusions – known in astronomy as occultations – are fun to watch, and can reveal the existence of close binary companions as they wink out behind the lunar limb. Several dozen occultations of stars brighter than +5th magnitude by the Moon happen each year, and the best events occur when the Moon is waxing and the stars disappear against its dark leading edge. We recently caught one such event last month when the Moon occulted the bright star Lambda Geminorum:
We are currently seeing the Moon cross the Hyades during every lunation until the year 2020, though it’s a particularly favorable time to catch the event in April 2014 as the Moon is a slender crescent. Notice that you can just make out the dark limb of the Moon with the naked eye? What you’re seeing is termed Earthshine, and that’s just what it is: the nighttime side of the Moon being illuminated by sunlight that is reflected off of the Earth. Standing on the Earthward side of the Moon, an observer would see a waning gibbous Earth about two degrees across. Yutu has a great view!
The occultation footprint for Delta Tauri^1. Credit: Occult 4.0
The Moon will cross its descending node where its apparent path intersects the ecliptic on April 1st (no joke, we swear) at 2:30 Universal Time or 10:30 PM EDT on March 31st. The next nodal crossing now occurs in just two weeks, and the Earth’s shadow will be there to greet the Moon on the morning of April 15th in the first of four total lunar eclipses that span 2014 and 2015. The month of April also sees the Moon’s orbit at its least eccentric, a time at which perigee – the Moon’s closest point to Earth – is at its most distant and apogee – its farthest point – is at its closest. This currently happens near the equinoxes, through the nodes slowly travel across the ecliptic completing one revolution every 18.6 years. Perigee can vary from 356,400 to 370,400 kilometres, and apogee can span a distance from 404,000 to 406,700 kilometres.
Looking west from the US SE at about 10PM local on the evening of April 3rd. Credit: Stellarium.
We’re also headed towards a “shallow year” in 2015 when the Moon has the least variability in respect to its declination. This trend will then reverse, climaxing with a “Long Nights Moon” riding high in the sky in 2025, which last occurred in 2006. The Moon will inch ever closer to Aldebaran on every successive lunation now, and begins a series of occultations of Aldebaran on January 29th, 2015 through the end of 2018. Occultations of Aldebaran always occur near these shallow years, and will be followed by a cycle of occultations of Regulus starting in 2017. We caught an excellent daytime occultation of Aldebaran by the Moon from North Pole, Alaska during the last cycle in the late 1990s.
The Moon passing between the Hyades and Pleiades in 2011 with Earthshine highlighted. Photos by author.
Now for the wow factor. Our Moon is 3,474 kilometres across and located just over one light second away. The Hyades star cluster covers about 6 ½ degrees of sky – about 7 times the size of the Full Moon – but is the closest open cluster to the Earth at 153 light years distant and has a core diameter of about 18 light years across. As mentioned previous, Aldebaran isn’t physically associated with the Hyades, but is merely located in the same direction at 65 light years distant.
The Hyades star cluster also provided early 20th astronomers with an excellent study in galactic motion. At an estimated 625 million years in age, the Hyades are slowly getting disbanded and strewn about the Milky Way galaxy in a process known as evaporation. The Hyades are also part of a larger stellar incorporation known as the Taurus Moving Cluster. Moving at an average of about 43 kilometres a second, the members of the Hyades are receding from us towards a divergent point near the bright star Betelgeuse in the shoulder of Orion. 50 million years hence, the Hyades will be invisible to the naked eye as seen from Earth, looking like a non-descript open cluster and providing a much smaller target for the Moon to occult at 20’ across. Astronomer Lewis Boss was the first to plot the motion of the Hyades through space in 1908, and the cluster stands as an essential rung on the cosmic distance ladder, with agreeing measurements independently made by both Hubble and Hipparcos and soon to be refined by Gaia.
Photographing and documenting this week’s passage of our Moon across the Hyades is easy with a DSLR camera: don’t be afraid to vary those ISO and shutter speeds to get the mix of the brilliant crescent Moon, the fainter earthshine, and background stars just right. The more adventurous might want to try actually catching the numerous occultations of bright stars on video. And U.S. and Canadian west coast observers are well placed to catch the Moon cross right though the core of the Hyades… a video animation of the event is not out of the question!
And from there, the Moon heads on to its date with destiny and a fine total lunar eclipse on April 15th which favors North American longitudes. We’ll be back later this week with our complete and comprehensive eclipse guide!
When you look into the night sky, you’re seeing tremendous distances away, even with your bare eyeball. But what’s the most distant object you can see with the unaided eye? And what if you get help with a pair of binoculars, a telescope, or even with the Hubble Space Telescope.
Standing at sea level, your head is at an altitude of 2 meters, and the horizon appears to be about 3 miles, or 5 km away. We’re able to see more distant objects if they’re taller, like buildings or mountains, or when we’re higher up in the air. If you get to an altitude of 20 meters, the horizon stretches out to about 11 km. But we can see objects in space which are even more distant with the naked eye. The Moon is 385,000 km away and the Sun is a whopping 150 million km. Visible all the way down here on Earth, the most distant object in the solar system we can see, without a telescope, is Saturn at 1.5 billion km away.
In the very darkest conditions, the human eye can see stars at magnitude 6.5 or greater. Which works about to about 9,000 individual stars. Sirius, the brightest star in the sky, is 8.6 light years. The most distant bright star, Deneb, is about 1500 light years away from Earth. If someone was looking back at us, right now, they could be seeing the election of the 52nd pope, St. Hormidas, in the 6th Century.
There are even a couple of really bright stars in the 8000 light year range, that we might just barely be able to see without a telescope. If a star detonates, we can see it much further away. The famous 1006 supernova was the brightest in history, recorded in China, Japan and the Middle East.
It was a total of 7,200 light years away and was visible in the daytime. There’s even large structures we can see. Outside the galaxy, the Large Magellanic Cloud is 160,000 light years and the Small Magellanic Cloud is almost 200,000 light years away. Unfortunately for us up North, these are only visible from Southern Hemisphere.The most distant thing we can see with our bare eyeballs is Andromeda at 2.6 million light years, which in dark skies looks like a fuzzy blob.
If we cheat and get a little help, say with binoculars – you can see magnitude 10 – fainter stars and galaxies at more than 10 million light-years away. With a telescope you can see much, much further. A regular 8-inch telescope would let you see the brightest quasars, more than 2 billion light years away. Using gravitational lensing the amazing Hubble space telescope can see galaxies, incredibly far out, where the light had left them just hundreds of millions of years after the Big Bang.
If you could see in other wavelengths, you could see different distances. Fortunately for our precious radiation sensitive organs, Gamma and X rays are blocked by our atmosphere. But if you could see in that spectrum, you could see objects exploding billions of light years away. And if you could see in the radio spectrum, you’d be able to see the cosmic microwave background radiation, surrounding us in all directions and marking the edge of the observable universe.
Wouldn’t that be cool? Well, maybe we can… just a little. Turn on your television, some of the static on the screen is this very background radiation, the afterglow of the Big Bang.
What do you think? If you could see far out in the Universe what would you like a close up view of? Tell us in the comments below.
