An artist's illustration of a planetary nebula engulfing its orbiting planets (image credit: Regulus36/deviantart, adjusted by DM to mitigate compression effects).
Textbooks often cite that planetary nebulae (PNe, plural) represent an endstate for lower-mass single stars. But conversely, recent research suggests that most PNe stem from binary systems. The lowest mass star theorized to form the typical PN is near 1 solar mass, and thus without a companion the Sun may not surpass the mass limit required to generate the hot glowing (ionized) nebula typically tied to PNe. New research continues to question our original understanding of how the Sun’s life may end.
A new study spearheaded by G. Jacoby aimed in part to test that binary hypothesis by searching for PNe in star clusters occupying M31. The team remarked that, “while the binary interaction model explains some of the anomalies associated with the observed planetary nebula population, this theory awaits final confirmation.”
“The traditional theory states that the progenitors of PNe are low- to intermediate-mass single stars … However, this theory does not provide a natural explanation for the non-spherical morphologies observed for the great majority of PNe, nor their low rate of formation. For these and other inconsistencies, a new paradigm has been developed, wherein most PNe are shaped via the interaction … with a binary companion,” said Jacoby et al. 2013. Continue reading “Astronomers Hint that our Sun won’t Terminate as the Typical Planetary Nebula”
Here’s a question… how long does it take sunlight to reach Earth? This sounds like a strange question, but think about it. Sunlight travels at the speed of light. Photons emitted from the surface of the Sun need to travel across the vacuum of space to reach our eyes.
The short answer is that it takes sunlight an average of 8 minutes and 20 seconds to travel from the Sun to the Earth.
If the Sun suddenly disappeared from the Universe (not that this could actually happen, don’t panic), it would take a little more than 8 minutes before you realized it was time to put on a sweater.
Here’s the math. We orbit the Sun at a distance of about 150 million km. Light moves at 300,000 kilometers/second. Divide these and you get 500 seconds, or 8 minutes and 20 seconds.
This is an average number. Remember, the Earth follows an elliptical orbit around the Sun, ranging from 147 million to 152 million km. At its closest point, sunlight only takes 490 seconds to reach Earth. And then at the most distant point, it takes 507 seconds for sunlight to make the journey.
But the story of light gets even more interesting, when you think about the journey light needs to make inside the Sun.
You probably know that photons are created by fusion reactions inside the Sun’s core. They start off as gamma radiation and then are emitted and absorbed countless times in the Sun’s radiative zone, wandering around inside the massive star before they finally reach the surface.
What you probably don’t know, is that these photons striking your eyeballs were ACTUALLY created tens of thousands of years ago and it took that long for them to be emitted by the sun.
Once they escaped the surface, it was only a short 8 minutes for those photons to cross the vast distance from the Sun to the Earth
As you look outward into space, you’re actually looking backwards in time.
The light you see from your computer is nanoseconds old. The light reflected from the surface of the Moon takes only a second to reach Earth. The Sun is more than 8 light-minutes away. And so, if the light from the nearest star (Alpha Centauri) takes more than 4 years to reach us, we’re seeing that star 4 years in the past.
There are galaxies millions of light-years away, which means the light we’re seeing left the surface of those stars millions of years ago. For example, the galaxy M109 is located about 83.5 million light-years away.
If aliens lived in those galaxies, and had strong enough telescopes, they would see the Earth as it looked in the past. They might even see dinosaurs walking on the surface.
If that title seems like an obvious statement to you, it’s ok… it seems pretty obvious to me too. But there are those who have been suggesting — for quite some time, actually — that earthquakes can be triggered or strengthened by solar activity; that, in fact, exceptionally powerful solar flares, coronal mass ejections, and other outpourings from our home star can cause the planet’s crust to shift, shake, and shudder.
Except that that’s simply not true — at least, not according to a recent study by researchers from the USGS.
“Recently there’s been a lot of interest in this subject from the popular press, probably because of a couple of larger and very devastating earthquakes. This motivated us to investigate for ourselves whether or not it was true.”
– Jeffrey Love, USGS Research Geophysicist
Even when an earthquake may have been found to occur on the same day as increased solar activity, at other times during even stronger quakes the Sun may have been relatively quiet, and vice versa.
Damage in Anchorage from an earthquake on March 27, 1964. Solar activity at the time was unexceptional. (U.S. Army photo)
“There have been some earthquakes like the 9.5 magnitude Chile quake in 1960 where, sure enough, there were more sunspots and more geomagnetic activity than on average,” said Dr. Love. “But then for the Alaska earthquake in 1964 everything was lower than normal. There’s no obvious pattern between solar activity and seismicity, so our results were inconclusive.”
Basically, even though our planet orbits within the Sun’s outer atmosphere and we are subject to the space weather it creates — and there’s still a lot to be learned about that — observations do not indicate any connection between sunspots, flares, and CMEs and the shifting of our planet’s crust (regardless of what some may like to suggest.)
“It’s natural for scientists to want to see relationships between things,” said Love. “Of course, that doesn’t mean that a relationship actually exists!”
The team’s findings were published in the March 16, 2013 online edition of Geophysical Research Letters.
NASA's Solar Dynamics Observatory captured this image of an M6.5 class flare at 3:16 EDT on April 11, 2013. This image shows a combination of light in wavelengths of 131 and 171 Angstroms. Credit: NASA/SDO.
The Solar Dynamics Observatory captured this view as the Sun let loose with its biggest solar flare of the year so far. It’s not a real big one — a mid-level flare classified as an M6.5 – but an associated coronal mass ejection is heading towards Earth and could spur some nice auroae by this weekend. Spaceweather.com predicts the expanding cloud (see animation below) will probably deliver a glancing blow to Earth’s magnetic field late on April 12th or more likely April 13th. The NOAA Space Prediction Center forecasts this event to cause moderate (G2) Geomagnetic Storm activity, and predicts geomagnetic activity to start in the mid to latter part (UTC) of April 13. They add that the source region is still potent and well-positioned for more geoeffective activity in the next few days.
The magnetic field of sunspot AR1719 erupted on April 11th at 0716 UT, producing an M6-class solar flare. Coronagraph images from the Solar and Heliospheric Observatory show a CME emerging from the blast site of the M6.5 solar flare. Credit: NASA
NASA’s Solar Dynamics Observatory captured this image of an M6.5 class flare at 3:16 am EDT on April 11, 2013. This image shows a combination of light in wavelengths of 131 and 171 Angstroms. Credit: NASA/SDO.
Our own Sun produces flares, but we are protected by our magnetosphere, and by the distance from the Sun to Earth. Credit: NASA/ Solar Dynamics Observatory,
Twice a year, the Solar Dynamics Observatory performs a 360-degree roll about the axis on which it points toward the Sun. This produces some unique views, but the rolls are necessary to help calibrate the instruments, particularly the Helioseismic and Magnetic Imager (HMI) instrument, which is making precise measurements of the solar limb to study the shape of the Sun. The rolls also help the science teams to know how accurately the images are aligned with solar north.
But take this rolling imagery, add some goofy music and hopefully it adds a smile to your day!
A large prominence from the Sun, on April 1, 2013. Credit and copyright: Paul Andrew.
Here are three images showing large prominences recently lifting off from the Sun’s surface. Solar prominences are sheets or arcs of luminous gas emanating from the Sun’s surface. They can loop hundreds of thousands of kilometers into space. In the image below by noted Australian amatuer Monty Leventhal, he estimates the prominence he captured stretches 233,000 km! Against the Sun, prominences appear dark, but against the sky they appear brighter. Prominences are held above the Sun’s surface by strong magnetic fields and can sometimes last for long periods of time.
See more and varied views below:
A negative image of the Sun and large prominences on March 31, 2013. Credit and copyright: César Cantú.This digital filtergram shows an active prominence on the SE limb of the Sun, stretching across for approximately 233,000 km on March 27, 2013. Credit and copyright: Monty Leventhal.
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.
A big Sun sets behind the trees in Cairns, Queensland, Australia. Credit and copyright: Joseph Brimacombe.
They say that perspective is everything. In this case perspective and filters are what makes this such a great astrophoto! We’ve been following Joseph Brimacombe’s astrophotography for years, and have come to appreciate his ‘perspective!” This great zoom shot of the setting Sun was taken on March 31, 2013 using a calcium K-line Filter, using a a 60 mm Lunt CaK Solar Telescope at F/8.3 and a Skynyx 2-2 camera. It’s a single shot, but below, you can watch a negative version of the Sun sink below the horizon in a video of 1,350 frames shown at double speed.
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.
Recent sunspot counts fall short of predictions. Credit: Dr. Tony Philips & NOAA/SWPC.
2013 was supposed to be the year of Solar Max, the peak of the 11-year sunspot cycle. But so far, solar activity has been fairly low, with sunspot numbers well below expectations as well as infrequent solar flares.
Back in 2008, the NOAA/NASA Solar Cycle Prediction Panel, said that due to the extrememly deep and quite solar minimum going on at that time, they anticipated Solar Cycle 24 – our current cycle – to be below average in intensity. They’ve certainly been right about that.
In this video, solar physicist Dean Pesnell of the Goddard Space Flight Center says that this solar max looks different from what we expected because it may end up being “double peaked.”
This video shows the low amount of sunspots so far in 2013:
Sunspot 1678 in Hydrogen alpha light, taken on February 19, 2013. Credit and copyright: Paul Andrew.
On February 19 and 20, 2013, scientists watched a giant sunspot form in under 48 hours. It has grown to over six Earth diameters. This image by astrophotographer Paul Andrew shows a detailed, close-up view of this sunspot group, named AR 1678, imaged with a hydrogen alpha filter.
NASA said the spot quickly evolved into what’s called a delta region, which has a magnetic field that harbors energy for strong solar flares. NOAA forecasters estimate a 45% chance of M-flares and a 15% chance of X-flares during the next day.
Below is an image from the Solar Dynamics Observatory of this region on the Sun:
This image of AR 1678 combines images from two instruments on NASA’s Solar Dynamics Observatory (SDO): the Helioseismic and Magnetic Imager (HMI), which takes pictures in visible light that show sunspots and the Advanced Imaging Assembly (AIA), which took an image in the 304 Angstrom wavelength showing the lower atmosphere of the sun, which is colorized in red. Credit: NASA/SDO/AIA/HMI/Goddard Space Flight Center
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.
Screenshot of a dazzling magnetic display on the Sun, a phenomenon known as coronal rain. Credit: NASA/SDO
This footage was obtained by the AIA instrument on the Solar Dynamics Observatory on July 19, 2012. It provides a stunning display of solar activity and shows how wildly different events on the Sun can be. Some come just with a solar flare, some with an additional ejection of solar material called a coronal mass ejection (CME), and some with complex moving structures in association with changes in magnetic field lines that loop up into the Sun’s atmosphere, the corona.
This eruption produced all three.
A moderately powerful solar flare exploded on the Sun’s lower right hand limb, sending out light and radiation. Next came a CME, which shot off to the right out into space. And then, the Sun treated viewers to one of its dazzling magnetic displays — a phenomenon known as coronal rain.
Over the course of the next day, hot plasma in the corona cooled and condensed along strong magnetic fields in the region. Magnetic fields, themselves, are invisible, but the charged plasma is forced to move along the lines, showing up brightly in the extreme ultraviolet wavelength of 304 Angstroms, which highlights material at a temperature of about 50,000 Kelvin. This plasma acts as a tracer, helping scientists watch the dance of magnetic fields on the Sun, outlining the fields as it slowly falls back to the solar surface.
SDO collected one frame every 12 seconds, and the movie plays at 30 frames per second, so each second in this video corresponds to 6 minutes of real time. The video covers 12:30 a.m. EDT to 10:00 p.m. EDT on July 19, 2012.
