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Host: Fraser Cain
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Astrojournalists: Morgan Rehnberg, Sondy Springmann, Elizabeth Howell, Casey Dreier, David Dickinson, Nicole Gugliucci, Mike Simmons
Continue reading “Weekly Space Hangout – January 24, 2014: LEGO Mars Rover & the Supernova We Missed in the Star Party!”
Wow! Now here’s a supernova bright enough for even small telescope observers to see. And it’s in a bright galaxy in Ursa Major well placed for viewing during evening hours in the northern hemisphere. Doesn’t get much better than that! The new object was discovered last night by S.J. Fossey; news of the outburst first appeared on the Central Bureau for Astronomical Telegrams “Transient Objects Confirmation Page”
Astronomers are saying this new supernova is currently at magnitude +11 to +12, so its definitely not visible with the naked eye. You’ll need a 4 inch telescope at least to be able to see it. That said, at 12 million light years away, this is (at the moment) the brightest, closest supernova since SN 1993 J kaboomed in neighboring galaxy M81 21 years ago in 1993. M81 and M82, along with NGC 3077, form a close-knit interacting group.
It’s amazing it wasn’t found and reported sooner (update — see below, as perhaps it was!). M82 is a popular target for beginning and amateur astronomers; pre-discovery observations show it had already brightened to magnitude 13.9 on the 16th, 13.3 on the 17th and 12.2 on the 19th. Cold winter weather and clouds to blame?
M82 is a bright, striking edge-on spiral galaxy bright enough to see in binoculars. Known as the Cigar or Starburst Galaxy because of its shape and a large, active starburst region in its core, it’s only 12 million light years from Earth and home to two previous supernovae in 2004 and 2008. Neither of those came anywhere close to the being as bright as the discovery, and it’s very possible the new object will become brighter yet.
PSN J09554214+6940260 is a Type Ia supernova. Type Ia (one-a), a dry term describing one of the most catastrophic events in the universe. Here a superdense white dwarf, a star only about the size of Earth but with the gravitational power of a sun-size star, pulls hydrogen gas from a nearby companion down to its surface where it adds to the star’s weight.
When the dwarf packs enough pounds to reach a mass 1.4 times that of the sun, it can no longer support itself. The star suddenly collapses, heats to incredible temperatures and burns up explosively in a runaway fusion reaction. What we see here on Earth is the sudden appearance of a brand new star within the galaxy’s disk. Of course, it’s not really a new star, but rather the end of an aged one.
I know you’re as excited as I am to get a look at this spectacular new star the next clear night, so I’ve prepared a couple maps to help you find the galaxy. The best time to see the supernova is as soon as the sky gets dark when it’s already up in the northeastern sky above the Dipper Bowl, but since it’s circumpolar for mid-latitude observers, you can check it out any time of night.
My maps show its position for around 8 o’clock. When you dial in the galaxy in your telescope, look for a starry point along its long axis west and south of the nucleus. All the fury of this fantastic blast is concentrated in that meek spark of light glimmering in the galactic haze.
Good luck and enjoy watching one of the biggest show of fireworks the universe has to offer. We’ll keep you posted with the latest updates right here. For more photos and additional information, please see David Bishop’s excellent Latest Supernovae site. For charts with magnitudes to follow the supernova’s progress, visit the AAVSO’s Variable Star Plotter and type in ‘PSN J09554214+6940260’ for the star’s name. You can read more about the followup work by the Remanzacco Observatory team here.
UPDATE: Fraser and team from the Virtual Star Party actually imaged M82 on Sunday evening, and you can see it in the video below at the 22 minute mark. It really looks like a bright spot is showing up — and that’s about a day before it was announced. Did they catch it? In the video the galaxy appears upside down as compared to the images here:
UT reader Andrew Symes took a screenshot from the VSP, flipped it, and compared it with photo from Meineko Sakura from the Tao Astronomical Observatory it really appears the team caught the supernova before it was actually announced! Take a look:
No, this isn’t a distant view of the London Eye. This nebula with a giant star at its center is known as SBW2007, located in the Carina Nebula. Astronomers say it has striking similarities to a star that went supernova back in 1987, SN 1987A. Both stars had identical rings of the same size and age, which were travelling at similar speeds; both were located in similar HII regions; and they had the same brightness. We didn’t have the telescopic firepower back before 1987 like we do now, so we don’t have a closeup view of how SN 1987A looked before it exploded, but astonomers think SBW2007 is a snapshot of SN1987a’s appearance, pre-supernova.
Of course, no one can predict when a star will go supernova, and since SBW2007 is 20,000 light-years away, we don’t have any worries about it causing any problems here on Earth. But astronomers are certainly hoping they’ll have the chance to watch it happen.
SN 1987A is the closest supernova to that we’ve been able to study since the invention of the telescope and it has provided scientists with good opportunities to study the physical processes of an exploding star.
Below is the latest image of SN 1987A, courtesy of the National Radio Astronomy Observatory. You can read about their recent findings here, where they were able to image the newly formed dust from the explosion.
All stars die, some more violently than others.
Once our own Sun has consumed all the hydrogen fuel in its core, it too will reach the end of its life. Astronomers estimate this to be a short 7 billion years from now. For a few million years, it will expand into a red giant, puffing away its outer layers. Then it’ll collapse down into a white dwarf and slowly cool down to the background temperature of the Universe.
I’m sure you know that some other stars explode when they die. They also run out of fuel in their core, but instead of becoming a red giant, they detonate in a fraction of a second as a supernova.
So, what’s the big difference between stars like our Sun and the stars that can explode as supernovae?
Mass. That’s it.
Supernova progenitors – these stars capable of becoming supernovae – are extremely massive, at least 8 to 12 times the mass of our Sun. When a star this big runs out of fuel, its core collapses. In a fraction of a second, material falls inward to creating an extremely dense neutron star or even a black hole. This process releases an enormous amount of energy, which we see as a supernova.
If a star has even more mass, beyond 140 times the mass of the Sun, it explodes completely and nothing remains at all. If these other stars can detonate like this, is it possible for our Sun to explode?
Could there be some chain reaction we could set off, some exotic element a rare comet could introduce on impact, or a science fiction doomsday ray we could fire up to make the Sun explode?
Nope, quite simply, it just doesn’t have enough mass. The only way this could ever happen is if it was much, much more massive, bringing it to that lower supernovae limit.
In other words, you would need to crash an equally massive star into our Sun. And then do it again, and again.. and again… another half dozen more times. Then, and only then would you have an object massive enough to detonate as a supernova.
Now, I’m sure you’re all resting easy knowing that solar detonation is near the bottom of the planetary annihilation list. I’ve got even better news. Not only will this never happen to the Sun, but there are no large stars close enough to cause us any damage if they did explode.
A supernova would need to go off within a distance of 100 light-years to irradiate our planet.
According to Dr. Phil Plait from Bad Astronomy, the closest star that could detonate as a supernova is the 10 solar mass Spica, at a distance of 260 light-years. No where near close enough to cause us any danger.
So don’t worry about our Sun exploding or another nearby star going supernova and wiping us out. You can put your feet up and relax, as it’s just not going to happen.
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Continue reading “Weekly Space Hangout – January 3, 2014: Quadrantids & What’s Coming in 2014”
New observations confirm that young Nathan Gray’s discovery is indeed a supernova explosion, albeit a rather peculiar one. Nathan Gray, age 10, discovered a new cosmic source on October 30th that emerged in the constellation of Draco, and it was subsequently classified as a supernova candidate. Evidence available at the time was sufficiently convincing that Nathan was promptly heralded as the youngest individual to discover a supernova.
The discovery garnered world-wide attention, however, confirmation via a spectrum from a large telescope was necessary to unambiguously identify the target as a supernova. In addition, that observation would enable astronomers to determine the supernova class and identify the progenitor of the exploding star. In other words, was the star initially comparable in mass to the Sun and a member of a binary system, or was the original star significantly more massive and a neutron star is potentially all that remains?
The new observations were acquired by Lina Tomasella and Leonardo Tartaglia of the Padova-Asiago Supernova Group, and imply that the supernova stems from a star significantly more massive than the Sun. Andrea Pastorello, a member of that group, noted that the target’s spectrum displays the presence of hydrogen (specifically H-alpha emission), which rules out the scenario of a lower-mass progenitor in a binary system (those are classified as type Ia).
Features present in the observations led the astronomers to issue a preliminary supernova classification of type II-pec (peculiar). The blue spectral continuum is typical of a type IIn supernova, but the expansion velocity inferred from the hydrogen line (3100 km/s) is an order of magnitude larger than expected, which motivated the team to issue the aforementioned classification. Pastorello further noted that the target is somewhat similar to SN 1998s, and in general type II supernovae exhibit heterogeneous observational properties.
Nathan had been scanning astronomical images sent by David J. Lane (Saint Mary’s University) for months, and identified some potential sources that proved to be false detections or previous discoveries. However, the Padova-Asiago Supernova Group has now confirmed that isn’t the case this time. Indeed, the discovery means that Nathan officially unseats his sister Kathryn as the youngest person to discover a supernova, yet she is elated for her bother (see Nancy Atkinson’s article regarding Kathryn’s discovery).
Nathan, his sister, and parents Paul and Susan, formed a supernova search team in partnership with Lane. The original discovery images were obtained from the Abbey Ridge Observatory, which is stationed in Lane’s backyard.
Those desiring additional information on supernovae will find the videos below pertinent.
They are what is known as the “lighthouses” of the universe – rotating neutron stars that emit a focused beam of electromagnetic radiation that is only visible if you’re standing in it’s path. Known as pulsars, these stellar relics get their name because of the way their emissions appear to be “pulsating” out into space.
Not only are these ancient stellar objects very fascinating and awesome to behold, they are very useful to astronomers as well. This is due to the fact that they have regular rotational periods, which produces a very precise internal in its pulses – ranging from milliseconds to seconds.
Pulsars are types of neutron stars; the dead relics of massive stars. What sets pulsars apart from regular neutron stars is that they’re highly magnetized, and rotating at enormous speeds. Astronomers detect them by the radio pulses they emit at regular intervals.
The formation of a pulsar is very similar to the creation of a neutron star. When a massive star with 4 to 8 times the mass of our Sun dies, it detonates as a supernova. The outer layers are blasted off into space, and the inner core contracts down with its gravity. The gravitational pressure is so strong that it overcomes the bonds that keep atoms apart.
Electrons and protons are crushed together by gravity to form neutrons. The gravity on the surface of a neutron star is about 2 x 1011 the force of gravity on Earth. So, the most massive stars detonate as supernovae, and can explode or collapse into black holes. If they’re less massive, like our Sun, they blast away their outer layers and then slowly cool down as white dwarfs.
But for stars between 1.4 and 3.2 times the mass of the Sun, they may still become supernovae, but they just don’t have enough mass to make a black hole. These medium mass objects end their lives as neutron stars, and some of these can become pulsars or magnetars. When these stars collapse, they maintain their angular momentum.
But with a much smaller size, their rotational speed increases dramatically, spinning many times a second. This relatively tiny, super dense object, emits a powerful blast of radiation along its magnetic field lines, although this beam of radiation doesn’t necessarily line up with it’s axis of rotation. So, pulsars are simply rotating neutron stars.
And so, from here on Earth, when astronomers detect an intense beam of radio emissions several times a second, as it rotates around like a lighthouse beam – this is a pulsar.
The first pulsar was discovered in 1967 by Jocelyn Bell Burnell and Antony Hewis, and it surprised the scientific community by the regular radio emissions it transmitted. They detected a mysterious radio emission coming from a fixed point in the sky that peaked every 1.33 seconds. These emissions were so regular that some astronomers thought it might be evidence of communications from an intelligent civilization.
Although Burnell and Hewis were certain it had a natural origin, they named it LGM-1, which stands for “little green men”, and subsequent discoveries have helped astronomers discover the true nature of these strange objects.
Astronomers theorized that they were rapidly rotating neutron stars, and this was further supported by the discovery of a pulsar with a very short period (33-millisecond) in the Crab nebula. There have been a total of 1600 found so far, and the fastest discovered emits 716 pulses a second.
Later on, pulsars were found in binary systems, which helped to confirm Einstein’s theory of general relativity. And in 1982, a pulsar was found with a rotation period of just 1.6 microseconds. In fact, the first extrasolar planets ever discovered were found orbiting a pulsar – of course, it wouldn’t be a very habitable place.
When a pulsar first forms, it has the most energy and fastest rotational speed. As it releases electromagnetic power through its beams, it gradually slows down. Within 10 to 100 million years, it slows to the point that its beams shut off and the pulsar becomes quiet.
When they are active, they spin with such uncanny regularity that they’re used as timers by astronomers. In fact, it is said that certain types of pulsars rival atomic clocks in their accuracy in keeping time.
Pulsars also help us search for gravitational waves, probe the interstellar medium, and even find extrasolar planets in orbit. In fact, the first extrasolar planets were discovered around a pulsar in 1992, when astronomers Aleksander Wolszczan and Dale Frail announced the discovery of a multi-planet planetary system around PSR B1257+12 – a millisecond pulsar now known to have two extrasolar planets.
It has even been proposed that spacecraft could use them as beacons to help navigate around the Solar System. On NASA’s Voyager spacecraft, there are maps that show the direction of the Sun to 14 pulsars in our region. If aliens wanted to find our home planet, they couldn’t ask for a more accurate map.
We have written many articles about stars here on Universe Today. Here’s an article about a newly discovered gamma ray pulsar, and here’s an article about how millisecond pulsars spin so fast.
If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.
We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?
Young Canadian Nathan Gray, age 10, has discovered a supernova candidate in the field of the galaxy designated PGC 61330, which lies in the constellation of Draco (the dragon).
Nathan made the discovery while scanning astronomical images taken by Dave Lane, who runs the Abbey Ridge Observatory (ARO) which is stationed in Nova Scotia. Incidentally, Nathan may unseat his older sister, Kathryn Aurora Gray, as the youngest supernova discoverer by a mere 33 days.
Nothing is visible at the location of the supernova candidate in prior images of the field taken over the past two years, or Digitized Palomar Sky Survey images.
Kathryn Aurora Gray garnered worldwide fame when she discovered a supernova in the galaxy designated UGC 3378 (see the Universe Today article by Nancy Atkinson). The discovery eventually earned her an audience with astronauts such as Neil Armstrong (shown below).
Caroline Moore held the record prior to Kathryn as the youngest person to discover a supernova (Caroline was 14 at the time). Caroline subsequently had the honor of meeting President Obama at the White House (see the video below).
Supernova are immense explosions linked to the evolutionary end-state of certain stars. The explosions are so energetic that they can be observed in distant galaxies. Indeed, Nathan’s supernova could be some 600 million light years distant. Gazing into space affords humanity the opportunity to peer back in time. Despite the (finite) speed of light being a remarkable 300000 km/s, the light-rays must travel over “astronomical” distances.
There are several different classes of supernovae. For example, Type II supernovae are associated with larger mass stars. The Sun will not terminate as a supernova, but may potentially evolve into a standard (or not) planetary nebula (see the Universe Today post “Astronomers Hint that our Sun won’t Terminate as the Typical Planetary Nebula”).
Nathan’s discovery has been posted on the International Astronomical Union’s site, and its presence confirmed by US and Italian-based observers. Its provisional name is: PSN J18032459+7013306, and to get an official supernova designation a large telescope needs to confirm the unique supernova light signature (via a spectrum). Is the target a bona fide supernova?
“Given no motion, large distance from the galactic plane (ie. not likely a nova), and several optical confirmations, as well as its very close angular proximity to a faint galaxy, it is a supernova at any reasonable certainty,” said Lane, an astronomer in the Dept. of Astronomy & Physics at Saint Mary’s University, as well as the director of the Burke-Gaffney and Abbey Ridge astronomical observatories. “A significant fraction of
the supernova discoveries these days are not observed spectrographically due to the sheer number of them vs. telescope time.”
Nathan Gray is the son of Paul and Susan Gray.
*2013 10 31.9053 – update from the IAU: SN to be confirmed in PGC 61330 detected with 3 x 3 min images (exp 9 min). Astrometry: RA 18 03 24.12 Dec +70 13 26.4 (ref stars UCAC2) Photometry: 17.00CR +/-0.02 (USNO A2R Ref stars 163R, 170R, 172R, 173R). Measure on unfiltered image. Observer and measurer: Xavier Bros, ANYSLLUM OBSERVATORY, Ager, Spain. T-350mm f4.6. Link to image and further information: http://www.anysllum.com/PSN_PGC61330.jpg
As astute readers of Universe Today, you likely know what a supernova is: a stellar explosion that signals the end game for certain kinds of stars. Above, however, is a picture of a kilonova, which happens when two really dense objects come together.
This fireball arose after a short-term (1/10 of a second) gamma-ray burst came into view of the Swift space telescope on June 3. Nine days later, the Hubble Space Telescope looked at the same area to see if there were any remnants, and spotted a faint red object that was confirmed in independent observations.
It’s the first time astronomers have been able to see a connection between gamma-ray bursts and kilonovas, although it was predicted before. They’re saying this is the first evidence that short-duration gamma ray bursts arise as two super-dense stellar objects come together.
So what’s the connection? Astronomers suspect it’s this sequence of events:
“This observation finally solves the mystery of the origin of short gamma ray bursts,” stated Nial Tanvir of the University of Leicester in the United Kingdom, who is also the lead author.
“Many astronomers, including our group, have already provided a great deal of evidence that long-duration gamma ray bursts (those lasting more than two seconds) are produced by the collapse of extremely massive stars. But we only had weak circumstantial evidence that short bursts were produced by the merger of compact objects. This result now appears to provide definitive proof supporting that scenario.”
Check out more details on the burst on HubbleSite. The scientific paper associated with these results was published in Nature Aug. 3.
Source: NASA
I love this galaxy. Not only does M74 display a near perfect spiral form but if this latest supernova is the third to “go boom” in the galaxy in just 11 years. The new object, designated PSN J01364816+1545310, was discovered blazing near 12.4 magnitude by the Lick Observatory Supernova Search at Lick Observatory near San Jose, Calif. “PSN” stands for “possible supernova” and the long string of numbers give the object’s position in the sky using the celestial equivalents of latitude and longitude.
Update: The supernova has now been confirmed, and is now officially named SN 2013ej.
Additional information and imagery of this from the Remanzacco Observatory team can be found at their website, including an animation of a “before and after” the supernova exploded.
The Lick search uses a fully robotic or automated 30-inch (76 cm) telescope dedicated to scanning the skies for new supernovae. It nailed M74’s latest exploding star on July 25. Two previous supernovae flared in the galaxy – SN 2002ap and SN 2003gd – and rose to 12th and 13th magnitude respectively before fading away into obscurity.
Three’s the charm as they say. A team of astronomers using a spectrograph at the Faulkes Telescope South at Siding Spring, Australia teased apart the supernova’s light and now know exactly what blew up. It appears our newcomer was originally a supergiant star at least 8 times as massive as the sun. After a relatively brief lifetime measured in the millions of years, the supergiant gobbled up the last of its fuel. With the gas gauge on “empty” and no new energy being produced in the core to hold back the force of gravity, the star imploded, sending a shockwave rocketing back in the opposite direction that tore it to bits.
Called a Type II supernova explosion, the blast hurtles star stuff into space at up to 45,000 miles per second (70,000 km/sec). More amazing, a powerful supernova explosion can release as much energy as the sun during its entire 10 billion year lifetime. No wonder even small telescopes can spot these cataclysmic events from millions of light years away!
As additional photos and measurements come in, amateur astronomers with 8-inch and larger telescopes will have no problem spying the supernova once the last quarter moon departs the vicinity. It’s located 93″ (1.5′) east and 135″ (more than 2′) southeast of the galaxy’s core. The map and photo will help you track it down.
While M74 is relatively bright and appears spectacular in long-exposure photos, it looks like a large, dim featureless glow in smaller telescopes. Be patient and take your time to “star hop” to the supernova using the more detailed map. Matter of fact, you may want to wait until Tuesday morning or later to look. That’s when the waning moon will finally depart the area. Let’s hope our new guest remains bright.
Good luck meeting the latest star to mark the end of its life with the biggest blowout of all. For more information and photos, stop by Dave Bishop’s Latest Supernovae site.
* This article was updated at 6:30 pm CDT on 7/28/13