Category Archives: Astronomy

By Leah Crane

Credit: M. Weiss

This explosion puts the super in supernova. A blast about 4.5 million light-years away has released about 10 times more energy than the sun will emit in its entire lifetime, making it the most powerful supernova ever spotted.

Until now it wasnt clear that explosions this powerful were even possible, says Edo Berger at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. He and his colleagues found the supernova, called SN2016aps, using the Panoramic Survey Telescope and Rapid Response System in Hawaii.

Not only is SN2016aps the most powerful supernova ever spotted, it is the longest one we have found. We found this more than three years ago, and were still observing it usually we only can track a supernova for maybe a few months, says Berger.

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To create a supernova this bright and long-lasting, the star that exploded must have shed a shell of material making up about half of its mass before it blew up. When the explosion smashed through the shell like a wrecking ball at a speed of about 4600 kilometres per second, it would have created an extreme blast of radiation.

The big question mark is, how did a star, about a decade before it exploded, lose half of its mass? Its not something we see in the models, says Berger.

Models of this type of supernova predict that it should shed a shell of mass thousands of years before exploding, but the observations show that the shell was still so dense and close to the central blast that it must have been ejected within a few decades of the supernova.

Explosions like this one could help us learn about the supermassive stars that may have existed in the early universe.

We dont have stars like this in our own galaxy, so the only way we can find out about these stars is by looking for these really exotic explosions and then sort of recreate the crime scene to figure out what it was up to before it exploded, says Berger.

The fact that this explosion was so bright means we may be able to find more scenes of huge stars demises even further away.

Journal reference: Nature Astronomy, DOI: 10.1038/s41550-020-1066-7

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Astronomers have spotted the most powerful supernova ever - New Scientist News

Representative Image. (Photo: AFP)

International Astronomy Day is celebrated twice a year -- one in autumn and another in spring. The Astronomy Day 2020 is celebrated on May 2. The world will celebrate the next Astronomy Day on September 26.

On this day, museums, societies, astronomical institutions and planetariums organise seminars, workshops and other fun-filled activities to spread awareness about the world of astronomy.

According to starwalk.space, in 1973, Doug Berger, president of the Astronomical Association of Northern California, had organised the celebration of first Astronomy Day. The idea behind observing the day is to create awareness and educate people about the beautiful universe.

On International Astronomy Day, lets have a look at some of the quotes by famous astronauts.

1. Neil Amstrong about the moon: Its a brilliant surface in that sunlight. The horizon seems quite close to you because the curvature is so much more pronounced than here on earth. Its an interesting place to be. I recommend it.

2. Kalpana Chawla on achieving goals: Do something because you really want to do it. If youre doing it just for the goal and dont enjoy the path, then I think youre cheating yourself.

3. Sunita Williams on teamwork: You don't look at the big problem altogether, because I think it's a little intimidating. So you just take it one day at a time, meet the people who are going to meet with you, for you, and who you're going to work for, and really try to do the best job that you can. That's all teamwork, and that's what space travel is about.

4. Rakesh Sharma about his space experience: As anyone can imagine, going up into space was a very rich and memorable experience and yes, it was unforgettable too.

Read this article:

International Astronomy Day 2020: All You Need to Know - News18

Astronomers have determined that, on average, the Sun is quieter than other stars magnetically, and it's not clear why. The long-term meaning of this finding isn't clear either, but it implies the Sun could get even more active than it is now.

Our Sun is magnetically active, meaning it has a magnetic field that sometimes strengthens enough to spit out huge and powerful storms, as well as create dark regions on the surface called sunspots. This activity directly affects us on Earth, endangering satellites in orbit, humans in space, and even our power grid on the ground. This magnetic activity is cyclical, waxing and waning every 11 years.

The motivation behind the new work is that, while we understand a lot about the Sun's magnetic field, it's important to have an idea of how it behaves compared to other stars. For example, is it more or less active compared to other stars?

That's a good question, because we don't know much about the long-term behavior of the Sun. Astronomers started counting sunspots around the first time a telescope was used to look skyward, but it wasn't until 1878 that images were good enough to start looking at their total area and position on the Suns face, giving us an idea of how they changed the Sun's brightness. We can do better, though; ice cores on Earth show the presence of elemental isotopes that are affected by subatomic particles zipping through space, and these particles are affected by the Sun's magnetic field. So we can use them as a proxy for solar magnetic activity going back about 9,000 years.

But that's a paltry amount compared to the billions of years a star lives. And that's why new research looked to other stars to see how they behave, to compare them to the Sun. The idea is that by looking at their brightness over long periods of time they can see the stars dimming and brightening as sunspots (well, starspots) rotate into and out of view. More magnetically active stars will change more because they have more sunspots, while quiet stars will have a more stable brightness. And the more stars they can observe the better.

For this, the scientists who did the new research turned to the Kepler observatory, which for three years stared at a single spot in space to look for exoplanets, planets orbiting other stars. It did this by taking frequent brightness measurements of 150,000 stars, looking for dips in brightness when planets passed in front of them, making mini-eclipses. And that means Kepler got a lot of brightness measurements of the stars, which is perfect for this study.

Now, stars come in many different flavors: high mass, low mass, young, old, hot, cool so the astronomers had to cull the list to leave only stars as much like the Sun as possible, to make the comparison fair. To do this they picked stars close to the Sun's surface temperature of 5780K, chemical composition (heavy elements affect the way a star behaves), surface gravity (some stars are giants and have much lower gravity; these are inactive magnetically), and most importantlyrotation.

Why rotation? The spin of a star is what powers the magnetic field. It creates what's called a dynamo inside the star, a self-powered magnetic generator. A star that spins rapidly is likely to have a much stronger magnetic field, and therefore a more aggressive sunspot cycle, so the astronomers did what they could to limit their sample to stars with rotation periods close to the Sun's of about 24.5 days.

In the end they wound up with long-term Kepler data for 365 solar-type stars. They also had a group of over 3,500 stars that were very much like the Sun but for which no rotation period was known. Then they compared the changes in those stars' brightness with the Sun's.

What they found is surprising: The Sun is much quieter than other stars like it! While the Sun's median brightness variation is 0.07%, the other stars had a median of 0.36%, five times higher! That's even twice as much as the Sun's maximum variation of 0.2%.

Why? It's not clear. There's an idea that the Sun is reaching an age where it's going through a transition to a quieter magnetic cycle as its rotation slows over the eons. The other stars like the Sun may not be quite that old yet, so are still active.

Interestingly, when they looked at the group of stars for which no rotation had been measured, they tended to be quieter, too, like the Sun. Again, it's not clear why. Remember, these are all stars very much like the Sun, but we just don't know how rapidly they spin. If the Sun were a star a few dozen light years away, we'd have a hard time measuring its rotation rate, and it would be in this sample of stars. In that case these stars may represent the kind of activity the Sun is still capable of.

That's intriguing. It's entirely possible the Sun is very active on timescales longer than 9,000 years, which is far back as we can reliably measure. Perhaps over tens or hundreds of thousands of years the Sun's activity increases quite a bit, but we have no records of it.

That's concerning. While the timescale is long, and is probably not anything we need worry about for quite some time, it's still not comforting to think the Sun can be more active. The magnetic cycle is responsible not just for sunspots, but also for solar storms, cataclysmic eruptions of solar flares and coronal mass ejections. These have a big effect on satellites, humans in space, and even our power grid on the ground. It's very much in our interest to understand these cycles better!

This work is a great first step in understanding the Sun's long-term behavior. In the future, other space-based observatories are planned to look at stars like Kepler did, so the research can be extended, too. It's interesting to me that the observations Kepler made can be used for other kinds of science than what was originally intended, too. So much of astronomy just depends on looking up, and doing so in as many ways possible. That means there's a lot of overlap there. What else will learn as we plumb the depths of the data we collect?

Originally posted here:

Our Sun is magnetically quiet compared to other stars. But why? - SYFY WIRE

The nights are now milder as the days reach May, meaning more people could venture out at night in their backyards or roof for some stargazing, especially since many cities and countries are still in lockdown due to the coronavirus pandemic.

(Photo : Neale LaSalle from Pexels)The Eta Aquariid meteor shower will peak this May.

With the milder nights comes fantastic night-time displays, care of a super moon, and meteor showers--although this month is not as active as April was.

Still, there are a few things worth seeing.

For those who are interested, here are the astronomy and space-related events happening this month of May:

The Eta Aquariid meteor shower will produce a staggering 20 to 30 meteors per hour, which makes up for the lack of super-bright fireballs, according to the National Aeronautics and Space Administration's (NASA) Bill Cooke from the agency's Meteoroid Environment Office.

Those on the Southern Hemisphere will even see more meteor showers with around 40 fireballs streaking through the night sky per hour, according to the American Meteor Society (AMS).

However,Thrillistnoted that the moon might be too bright during the meteor shower's peak, so it could interfere with everyone's viewing, especially since the shower is often fast and faint.

But, it's still possible to watch the Eta Aquariid meteor shower a few hours before dawn when the moon has set for the night, and the sky is darker.

In addition, stargazers are advised to avoid looking at their phones as it could ruin their night vision.

It's good to catch this meteor shower as this is the last major one for now, and the next one won't happen until late July.

We've already experienced four supermoons in 2020 alone, but for those who aren't tired of our closest neighbor's spectacular show off, the last one for this year will happen on the evening of May 6 to the early morning of May 7.

For those who aren't aware, a supermoon is when the moon appears bigger and brighter than it usually is.

It's also worth seeing since, according toAccuWeather, the next one won't happen until April 2021.

In addition, May's full moon is also known as the Flower Moon since it's the start of Spring and the flowers and plants are starting to bloom once again after some harsh, winter months. Other names of May's full moon include the Milk Moon, Corn Planting Moon, and the Frog Moon.

Read Also:NASA ALlows Spacecraft of Elon Musk, Jeff Bezos to Land NASA Astronauts on Moon

Although Jupiter is millions of miles away fromour moonin reality, they will look closer in our perspectives on May 12 to May 13, from midnight to pre-dawn hours in the south-southeastern sky.

It's best to see them with the naked eye or with a pair of binoculars, as they won't be too close together to view with a telescope.

Just like with Jupiter, the red planet will be easier to spot in the night sky just before dawn, close to the moon in our perspectives.

There's a new comet in town--comet SWAN--which will be at its closest to the sun this mid-May and might be bright enough to be seen in our night sky.

Last month, comet ATLAS was the center of attention by astronomy lovers as it grew brighter, showing potential to shine brighter and become visible to the naked eye, untilit broke apartunexpectedly.

This month, comet SWAN might finally fulfill our thirst for a good comet show, with the comet making itsclosest approachto Earth on May 13.

Read Also:[VIDEO] NASA Captures Dancing Black Holes Creating Mega Flare Brighter Than Trillion Stars

2018 TECHTIMES.com All rights reserved. Do not reproduce without permission.

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The Night Sky This May: Here are the Top Astronomy Events You Can See This Month - Tech Times

Tuesday, April 28At magnitude 8.4, Vesta is within easy reach of most binoculars. To find it, locate Aldebaran, the brightest star in Taurus, and draw an imaginary line northeast. First, youll hit the open star cluster NGC 1647, which contains several dozen scattered 8th- to 11th- magnitude stars. Continue that line roughly the same distance to the northeast and begin scanning for Vesta, which is slowly advancing through a region with few background stars. Try this exercise two or three nights in a row to find the spot that has moved thats the asteroid youre looking for.

Wednesday, April 29Mars remains an ideal morning target to catch before sunrise. The Red Planet glows at magnitude 0.4 in the southeastern sky, positioned midway between two 4th-magnitude stars: Iota () and Gamma () Capricorni. Mars is nearly 20 above the horizon an hour before sunrise.

Mars also stands at the center of a planetary gathering. Look west to find Saturn nearly 19 away, with Jupiter just 5 farther in the same direction. These two solar system giants shine at magnitude 0.6 and 2.4, respectively. Telescopic observers and imagers can add a dwarf planet to the mix: Pluto is just 2 southwest of Jupiter, glinting faintly at magnitude 14.

Turn your telescope 30 east of Mars to glimpse magnitude 8 Neptune. The ice giant is still low on the eastern horizon, rising higher as the sky brightens with the coming dawn. See how long you can track it before the bright sky hides it from view.

Thursday, April 30First Quarter Moon occurs at 4:38 P.M. EDT. An hour after sunset, our satellite stands high in the southwestern sky in the faint constellation Cancer the Crab. In the moonlit sky, you might have better luck spotting Gemini the Twins and their bright luminaries, Castor and Pollux, to the west. Look east of the Moon to find Leo the Lion, with his brightest star Regulus, and follow the ecliptic farther east to reach Virgo the Maiden, whose brightest star is Spica. This blue-white magnitude 1 star is not one star, but two however, the stars are so close that they cannot be split visually. Instead, astronomers discovered Spicas dual nature by noticing that as one star orbits the other, gravitys effects shift the light we see from the star slightly red and then blue over time.

The larger of the two, Spica A, is roughly seven times wider than our Sun and 10 times as massive. Most of the light we see from the star comes from this component. The smaller Spica B is a little less than four times wider than the Sun and seven times as massive.

Friday, May 1 The Eta Aquariids have been slowly ramping up since last week and will peak in another few days. Its not one of the years best meteor showers, due to its low-altitude radiant in the Northern Hemisphere and low predicted rate of just 10 meteors per hour at its peak. But with Mars hanging nearby and a still-crescent Moon in the sky, its worth trying to catch a few shooting stars this morning.

Find the darkest skies possible and spend some time scanning overhead. Try concentrating on a spot away from the constellation Aquarius, where the showers meteors originate. You may only see five or so Eta Aquariid meteors an hour, but this is also a great chance to relax beneath the stars and get to know the morning sky much better.

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The Sky This Week from April 24 to May 1 - Astronomy Magazine

To date, astronomers have confirmed the existence of 4,152 extrasolar planets in 3,077 star systems. While the majority of these discoveries involved a single planet, several hundred star systems were found to be multi-planetary. Systems that contain six planets or more, however, appear to be rarer, with only a dozen or so cases discovered so far.

This is what astronomers found after observing HD 158259, a Sun-like star located about 88 light-years from Earth, for the past seven years using the SOPHIE spectrograph. Combined with new data from the Transiting Exoplanet Space Satellite (TESS), an international team reported the discovery of a six planet system where all were in near-perfect rhythm with each other.

The international team responsible for this discovery was led by Dr. Nathan Hara, a postdoctoral researcher at the University of Geneva (UNIGE), a member of the Swiss PlanetS institute, and a Fellow with the European Space Agencys (ESA) CHaracterising ExOPlanets Satellite (CHEOPS) mission. The study that describes their findings recently appeared in the journal Astronomy & Astrophysics.

Using SOPHIE, astronomers have been conducting velocity measurements of many stars in the northern hemisphere to determine if they have exoplanets orbiting them. This method, known as the Radial Velocity Method (or Doppler Spectroscopy), consists of measuring the spectra a star to see if it is moving in place which is an indication that the gravitational force of one or more planets is working on it.

Interestingly enough, it was SOPHIEs predecessor (the ELODIE spectrograph) that led to one of the earliest exoplanet discoveries in 1995 the hot Jupiter 51 Peg b (Dimidium). After examining HD 158259 for seven years, SOPHIE succeeded in obtaining high-precision radial velocity measurements that revealed the presence of a six planet system.

This system consists of an innermost large rocky planet (a super-Earth) and five small gas giants (mini-Neptunes) that have exceptionally regular spacing between them. As Franois Bouchy, a professor of astronomy and science at UNIGE and the coordinator of the observation program, explained in a UNIGE press release:

The discovery of this exceptional system has been made possible thanks to the acquisition of a great number of measurements, as well as a dramatic improvement of the instrument and of our signal processing techniques.

These planets range from being 2 (the innermost super-Earth) to 6 times (the mini-Neptunes) as massive as Earth. The system is also very compact, with all of six planets orbit closely to the star and the outermost being just 0.38 times as distant as Mercury is from the Sun. This places the planets well inside the stars habitable zone (HZ), which means none are likely to have water on the surfaces or dense enough atmospheres to support life.

Meanwhile, TESS monitored HD 158259 for signs of transits (aka. the Transit Method) and observed a decrease in the stars brightness as the innermost planet passed in front of the star. According to Isabelle Boisse, a researcher at the Marseille Astrophysics Laboratory and co-author of the study, the TESS readings (combined with the radial velocity data) allowed them to constrain the properties of this planet (HD 158259 b) further.

The TESS measurements strongly support the detection of the planet and allow to estimate its radius, which brings very valuable information on the planets internal structure, she said. But as noted earlier, the most impressive feature of this system is its regularity. Basically, the planets in the system have an almost exact 3:2 orbital resonance

This means that for every three orbits the innermost planet makes, the second one will complete about two. In the time it takes the second planet to complete three orbits, the third will complete about two. This ratio applies to all six planets in the system and came as quite a surprise to Hara and his colleagues.

When describing the planets orbits, Hara compared it to an orchestra playing music, though the arrangement is not quite perfect:

This is comparable to several musicians beating distinct rhythms, yet who beat at the same time at the beginning of each bar. Here, about is important. Besides the ubiquity of the 3:2 period ratio, this constitutes the originality of the system.

Resonances, even imperfect ones, are of interest to astronomers because of how they provide hints to a star systems formation and evolution. In astronomical circles, there is still considerable debate about how star systems come together and change over time. A particularly contentious point is whether planets form close to their final position in the system, or if they change their orbits after forming.

This latter scenario (known as planetary migration) has been gaining traction in recent years thanks to the discovery of exoplanets like Hot-Jupiters, leading many astronomers to question if planetary shake-ups occur. This theory would appear to explain the formation of the six planets in the HD 158259 system. Said Stephane Udry, a professor of astronomy and science at UNIGE:

Several compact systems with several planets in, or close to resonances are known, such as TRAPPIST-1 or Kepler-80. Such systems are believed to form far from the star before migrating towards it. In this scenario, the resonances play a crucial part.

The fact that HD 158259s planets are close to a 3:2 resonance, but not exactly within one, suggests that they were trapped in one in the past. However, they would have subsequently undergone synchronous migration and moved away from the resonance. According to Hara, thats not all that this system can tell us.

Furthermore, the current departure of the period ratios from 3:2 contains a wealth of information, he said. With these values on the one hand, and tidal effect models on the other hand, we could constrain the internal structure of the planets in a future study. In summary, the current state of the system gives us a window on its formation.

The more we learn about this multi-planet system and others like it, the more we can learn about how star systems like our own came to be. The resolution of these and other questions about the formation and evolution of planetary systems will put us one step closer to knowing how life can emerge (and perhaps where to look for it!)

Further Reading: University of Geneva, Astronomy & Astrophysics

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Astronomers Find a Six-Planet System Which Orbit in Lockstep With Each Other - Universe Today

A nova is a dramatic episode in the life of a binary pair of stars. It's an explosion of bright light that can last weeks or even months. And though they're not exactly rare - there are about 10 each year in the Milky Way - astronomers have never watched one from start to finish.

Until now.

A nova occurs in a close binary star system, when one of the stars has gone through its red giant phase. That star leaves behind a remnant white dwarf. When the white dwarf and its partner become close enough, the massive gravitational pull of the white dwarf draws material, mostly hydrogen, from the other star.

That hydrogen accretes onto the surface of the white dwarf, forming a thin atmosphere. The white dwarf heats the hydrogen, and eventually the gas pressure is extremely high, and fusion is ignited. Not just any fusion: rapid, runaway fusion.

Artist's impression of a nova eruption, showing the white dwarf accreting matter from its companion. (Nova_by K. Ulaczyk, Warschau Universitt Observatorium)

When the rapid fusion ignites, we can see the light, and the new hydrogen atmosphere is expelled away from the white dwarf into space. In the past, astronomers thought these new bright lights were new stars, and the name "nova" stuck.

Astronomers now call these types of nova "classical" novae. (There are also recurrent novae, when the process repeats itself.)

This is an enormously energetic event, that produces not only visible light, but gamma rays and x-rays too. The end result is that some stars that could only be seen through a telescope can be seen with the naked eye during a nova.

All of this is widely accepted in astronomy and astrophysics. But much of it is theoretical.

Recently, astronomers using the BRITE (BRIght Target Explorer) constellation of nanosatellites were fortunate enough to observe the entire process from start to finish, confirming the theory.

BRITE is a constellation of nanosatellites designed to "investigate stellar structure and evolution of the brightest stars in the sky and their interaction with the local environment," according to the website.

They operate in low-Earth orbit and have few restrictions on the parts of the sky that they can observe. BRITE is a coordinated project between Austrian, Polish, and Canadian researchers.

This first-ever observation of a nova was pure chance. BRITE had spent several weeks observing 18 stars in the Carina constellation. One day, a new star appeared. BRITE Operations Manager Rainer Kuschnig found the nova during a daily inspection.

"Suddenly there was a star on our records that wasn't there the day before," he said in a press release. "I'd never seen anything like it in all the years of the mission!"

Werner Weiss is from the Department of Astrophysics at the University of Vienna. In a press release, he emphasized the significance of this observation.

A shows bright V906 Carinae labelled with a white arrow. B and C show the star before and after the V906 Carinae nova. (A. Maury and J. Fabrega)

"But what causes a previously unimpressive star to explode? This was a problem that has not been solved satisfactorily until now," he said.

The explosion of Nova V906 in the constellation Carina is giving researchers some answers and has confirmed some of the theoretical concept behind novae.

V906 Carinae was first spotted by the All-Sky Automated Survey for Supernovae. Fortunately, it appeared in an area of the sky that had been under observation by BRITE for weeks, so the data documenting the nova is in BRITE data.

"It is fantastic that for the first time a nova could be observed by our satellites even before its actual eruption and until many weeks later," says Otto Koudelka, project manager of the BRITE Austria (TUGSAT-1) satellite at TU Graz.

V906 Carinae is about 13,000 light years away, so the event is already history. "After all, this nova is so far away from us that its light takes about 13,000 years to reach the earth," explains Weiss.

The BRITE team reported their findings in a new paper. The paper is titled "Direct evidence for shock-powered optical emission in a nova." It's published in the journal Nature Astronomy. First author is Elias Aydi from Michigan State University.

"This fortunate circumstance was decisive in ensuring that the nova event could be recorded with unprecedented precision," explains Konstanze Zwintz, head of the BRITE Science Team, from the Institute for Astro- and Particle Physics at the University of Innsbruck.

Zwintz immediately realised "that we had access to observation material that was unique worldwide," according to a press release.

Novae like V906 Carinae are thermonuclear explosions on the surface of white dwarf stars. For a long time, astrophysicists thought that a nova's luminosity is powered by continual nuclear burning after the initial burst of runaway fusion. But the data from BRITE suggests something different.

In the new paper, the authors show that shocks play a larger role than thought. The authors say that "shocks internal to the nova ejecta may dominate the nova emission."

These shocks may also be involved in other events like supernovae, stellar mergers, and tidal disruption events, according to the authors. But up until now, there's been a lack of observational evidence.

"Here we report simultaneous space-based optical and gamma-ray observations of the 2018 nova V906 Carinae (ASASSN-18fv), revealing a remarkable series of distinct correlated flares in both bands," the researchers write.

Since those flares occur at the same time, it implies a common origin in shocks.

"During the flares, the nova luminosity doubles, implying that the bulk of the luminosity is shock powered." So rather than continual nuclear burning, novae are driven by shocks.

"Our data, spanning the spectrum from radio to gamma-ray, provide direct evidence that shocks can power substantial luminosity in classical novae and other optical transients."

In broader terms, shocks have been shown to play some role in events like novae. But that understanding is largely based on studying timescales and luminosities. This study is the first direct observation of such shocks, and is likely only the beginning of observing and understanding the role that shocks play.

In the conclusion of their paper the authors write: "Our observations of nova V906 Car definitively demonstrate that substantial luminosity can be produced - and emerge at optical wavelengths - by heavily absorbed, energetic shocks in explosive transients."

They go on to say that: "With modern time-domain surveys such as ASAS-SN, the Zwicky Transient Facility (ZTF) and the Vera C. Rubin Observatory, we will be discovering more - and higher luminosity - transients than ever before. The novae in our galactic backyard will remain critical for testing the physical drivers powering these distant, exotic events."

This article was originally published by Universe Today. Read the original article.

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Astronomers Have Watched a Nova Go From Start to Finish For The First Time - ScienceAlert

"Clearly, Fomalhaut b was doing things a bona fide planet should not be doing," Gspr said.

The last straw for Fomalhaut b was when researchers looked at Hubble images from 2014, which revealed the object had vanished altogether. Though there could be reasons why an exoplanet fades, they certainly dont just disappear.

This led researchers to conclude that Fomalhaut b was nothing more than a planetary mirage namely, an energetic cloud of debris blasted from a collision between two large icy objects. Then, as the cloud dispersed, the faux-planet Fomalhaut b dissolved into nothingness. Based on the evolving shape and location of the debris, the researchers estimate the original colliding bodies were each likely a mix of ice and dust measuring about 125 miles (200 kilometers) across.

Unfortunately, Hubble seems to have been late for the main event, as the researchers think the crash happened right before the telescope began observing the system in 2004. But just detecting the results of such a violent cosmic event is exciting, they say. According to the researchers calculations, such a massive collision may only happen once every 200,000 years in a given system.

Astronomers hope to further study the Fomalhaut system with the upcoming the James Webb Space Telescope during its first year of operations. The future observations will hopefully answer questions about Fomalhauts asteroid belt, as well as about any legitimate planets actually orbiting the star.

Originally posted here:

Hubble watches a suspected exoplanet disappear before its very eyes - Astronomy Magazine

A nova is a dramatic episode in the life of a binary pair of stars. Its an explosion of bright light that can last weeks or even months. And though theyre not exactly rarethere are about 10 each year in the Milky Wayastronomers have never watched one from start to finish.

Until now.

A nova occurs in a close binary star system, when one of the stars has gone through its red giant phase. That star leaves behind a remnant white dwarf. When the white dwarf and its partner become close enough, the massive gravitational pull of the white dwarf draws material, mostly hydrogen, from the other star.

That hydrogen accretes onto the surface of the white dwarf, forming a thin atmosphere. The white dwarf heats the hydrogen, and eventually the gas pressure is extremely high, and fusion is ignited. Not just any fusion: rapid, runaway fusion.

When the rapid fusion ignites, we can see the light, and the new hydrogen atmosphere is expelled away from the white dwarf, into space. In the past, astronomers thought these new bright lights were new stars, and the name nova stuck. Astronomers now call these types of nova classical novae. (There are also recurrent novae, when the process repeats itself.)

Suddenly there was a star on our records that wasnt there the day before.

This is an enormously energetic event, that produces not only visible light, but gamma rays and x-rays too. The end result is that some stars that could only be seen through a telescope can be seen with the naked eye during a nova.

All of this is widely accepted in astronomy and astrophysics. But much of it is theoretical. Recently, astronomers using the BRITE (BRIght Target Explorer) Constellation of nanosatellites were fortunate enough to observe the entire process from start to finish, confirming the theory.

BRITE is a constellation of nanosatellites designed to investigate stellar structure and evolution of the brightest stars in the sky and their interaction with the local environment, according to the website. They operate in Low-Earth Orbit and have few restrictions on the parts of the sky that they can observe. BRITE is a coordinated project between Austrian, Polish, and Canadian researchers.

This first-ever observation of a nova was pure chance. BRITE had spent several weeks observing 18 stars for several weeks in the Carina constellation. One day, a new star appeared. BRITE Operations Manager Rainer Kuschnig found the nova during a daily inspection. Suddenly there was a star on our records that wasnt there the day before, he said in a press release. Id never seen anything like it in all the years of the mission!

Professor Werner Weiss is from the Department of Astrophysics at the University of Vienna. In a press release, he emphasized the significance of this observation. But what causes a previously unimpressive star to explode? This was a problem that has not been solved satisfactorily until now, he said. The explosion of Nova V906 in the constellation Carina is giving researchers some answers and has confirmed some of the theoretical concept behind novae.

It is fantastic that for the first time a nova could be observed by our satellites even before its actual eruption and until many weeks later.

V906 Carinae was first spotted by the All-Sky Automated Survey for Supernovae. Fortunately, it appeared in an area of the sky that had been under observation by BRITE for weeks, so the data documenting the nova is in BRITE data. It is fantastic that for the first time a nova could be observed by our satellites even before its actual eruption and until many weeks later, says Prof. Otto Koudelka, project manager of the BRITE Austria (TUGSAT-1) satellite at TU Graz.

V906 Carinae is about 13,000 light years away, so the event is already history. After all, this nova is so far away from us that its light takes about 13,000 years to reach the earth, explains Weiss.

The BRITE team reported their findings in a new paper. The paper is titled Direct evidence for shock-powered optical emission in a nova. Its published in the journal Nature Astronomy. First author is Elias Aydi from Michigan State University.

This fortunate circumstance was decisive in ensuring that the nova event could be recorded with unprecedented precision, explains Prof. Konstanze Zwintz, head of the BRITE Science Team, from the Institute for Astro- and Particle Physics at the University of Innsbruck. Zwintz immediately realised that we had access to observation material that was unique worldwide, according to a press release.

Novae like V906 Carinae are thermonuclear explosions on the surface of white dwarf stars. For a long time, astrophysicists thought that a novas luminosity is powered by continual nuclear burning after the initial burst of runaway fusion. But the data from BRITE suggests something different.

In the new paper, the authors show that shocks play a larger role than thought. The authors say that shocks internal to the nova ejecta may dominate the nova emission. These shocks may also be involved in other events like supernovae, stellar mergers, and tidal disruption events, according to the authors. But up until now, theres been a lack of observational evidence.

Here we report simultaneous space-based optical and ?-ray observations of the 2018 nova V906 Carinae (ASASSN-18fv), revealing a remarkable series of distinct correlated flares in both bands, the researchers write. Since those flares occur at the same time, it implies a common origin in shocks.

During the flares, the nova luminosity doubles, implying that the bulk of the luminosity is shock powered. So rather than continual nuclear burning, novae are driven by shocks. Our data, spanning the spectrum from radio to gamma-ray, provide direct evidence that shocks can power substantial luminosity in classical novae and other optical transients.

In broader terms, shocks have been shown to play some role in events like novae. But that understanding is largely based on studying timescales and luminosities. This study is the first direct observation of such shocks, and is likely only the beginning of observing and understanding the role that shocks play.

In the conclusion of their paper the authors write Our observations of nova V906 Car definitively demonstrate that substantial luminosity can be producedand emerge at optical wavelengthsby heavily absorbed, energetic shocks in explosive transients.

They go on to say that With modern time-domain surveys such as ASAS-SN, the Zwicky Transient Facility (ZTF) and the Vera C. Rubin Observatory, we will be discovering moreand higher luminositytransients than ever before. The novae in our galactic backyard will remain critical for testing the physical drivers powering these distant, exotic events.

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Astronomers Watch a Nova Go From Start to Finish for the First Time - Universe Today

Little is more enticing than the prospect of seeing alien worlds around other starsand perhaps one day even closely studying their atmosphere and mapping their surface. Such observations are exceedingly difficult, of course. Although more than 4,000 exoplanets are now known, the vast majority of them are too distant and dim for our best telescopes to discern against the glare of their host star. Exoplanets near our solar system provide easier imaging opportunities, however. And no worlds are nearer to us than those thought to orbit the cool, faint red dwarf Proxima Centaurithe closest star to our sun at 4.2 light-years away.

In 2016 astronomers discovered the first known planet in this system: the roughly Earth-sized Proxima b. But because of its star-hugging 11-day orbit around Proxima Centauri, Proxima b is a poor candidate for imaging. Proxima c, by contrast, offers much better chances. Announced in 2019, based on somewhat circumstantial evidence, the planet remains unconfirmed. If real, it is estimated to be several times more massive than Eartha so-called super Earth or mini Neptuneand to orbit Proxima Centauri at about 1.5 times the span between Earth and the sun. Its size and distance from its star make the world a tempting target for current and near-future exoplanet-imaging projects. Now, in a new preprint paper accepted for publication in the journal Astronomy & Astrophysics, some astronomers say they mightjust might have managed to see Proxima c for the first time.

This planet is extremely interesting because Proxima is a star very close to the sun, says Raffaele Gratton of the Astronomical Observatory of Padova in Italy, who is the studys lead author. The idea was that since this planet is [far] from the star, it is possible that it can be observed in direct imaging. We found a reasonable candidate that looks like we have really detected the planet.

Last year Gratton and his team were first alerted to the possibility of imaging the planet by Mario Damasso of the Astrophysical Observatory of Turin in Italy, who was the lead author of the original paper on Proxima cs possible discovery. Damasso and his colleagues had presented evidence for Proxima cs existence based on its stars telltale wobbling, which they inferred was caused by the pull of an unseen orbiting planet. Confirming a worlds existence in this way requires seeing the same wobble occur againand againin a process that often takes many months or even years. Damasso wondered if there might be another way. Thus, he asked Gratton and his team to look through data from the SPHERE (Spectro-Polarimetric High-Contrast Exoplanet Research) instrument on the European Southern Observatorys Very Large Telescope (VLT) in Chile to see if they could actually see the planet. As soon as our paper on Proxima c was considered for publication, I contacted [Gratton] to discuss the possibility of pushing SPHERE to its limits, Damasso says. The [planetary] system is potentially so cool that it is worthy to try other techniques.

If you squint a bit while staring at the SPHERE data, a picture of the mysterious planet seems to swim into view. By focusing on Proxima cs predicted position and separation from its star within multiple, stacked infrared images from SPHERE, Gratton and his colleagues were able to pick out 19 potential appearances of the planet across several years of routine observations. Of these candidate detections, one stood out as being particularly enticing: it appeared in the images about six times brighter than their noisethat is, unwanted light from artifacts or background stars. Its a possible candidate that has a low probability of being a false alarm, says Emily Rickman of the Geneva Observatory, who is a co-author of the paper.

If that detection is genuine, it poses intriguing questions. The object believed to be the planet would be at least seven times the mass of Earthlarge enough to place it firmly beyond the super Earth category. This would definitely be some kind of mini Neptune, says Sara Seager, a professor of planetary science at the Massachusetts Institute of Technology, who was not involved in the new paper. The object also appears to be 10 to 100 times brighter than a planet of its mass should be. This luminosity, the study authors reason, couldarise from a large amount of dust surrounding the planet, perhaps in a vast ring system that is three to four times larger than that of Saturn. To some, that situation seems too strange to be true.

It would be a huge ring system around a relatively old star, says astrophysicist Bruce Macintosh of Stanford University, who also was not part of the work. Its certainly possible for things like this to exist. But for your first detection of something like this to have that massive ring system, youd have to postulate a universe in which most Neptune-sized planets have massive ring systems enormously bigger than Saturns. And that seems like an unlikely universe to live in.

If genuine, this detectionthis imagewould have profound implications for our understanding of our nearest neighboring planetary system. It would give us definitive proof of the existence of Proxima c and also provide the angle at which the planet orbits its star, relative to our ownsomething that watching a stars wobbles alone cannot provide. The detection would also all but ensure that we could soon study the planets atmosphere with a new generation of powerful observatories, such as the upcoming European Extremely Large Telescope (E-ELT) and NASAs Wide-Field Infrared Survey Telescope (WFIRST).

Perhaps more importantly, pinning down Proxima c would also likely reveal the orbital angle of Proxima b, because planets would be expected to orbit in the same plane like those in our solar system do. This information, coupled with the wobbles Proxima b raises on its star, would tell us that world must be somewhere between 1.5 and 1.8 times the mass of Earth, which would let us refine theories about its characteristics. Such a mass would strongly point to the fact [that Proxima b] is rocky, says Elizabeth Tasker, an exoplanet scientist at the Japan Aerospace Exploration Agency, who was not involved in the study. In addition to our knowledge that Proxima b orbits in its stars habitable zone, where liquid water and thus life as we know it can exist, proof that the world is rocky would catapult it to the top of any astrobiologists list of promising exoplanets.

Such spectacular possibilities, however, call for steely-eyed skepticism. Indeed, the new papers authors acknowledge there is a decent chance their image is not actually a planet at all but rather just random noise in the data. They also note that the apparent motion of their putative planet conflicts with earlier estimates of Proxima cs position, based on observations of its star made by the European Space Agencys Gaia spacecraft. Thus, other astronomers are treating the potential finding with a considerable amount of caution. Its tough for me to conclude that [this] is a decisive detection, says Thayne Currie, an exoplanet scientist at NASAs Ames Research Center, who was also not part of the work.

Unfortunately, the ongoing global shutdown in response to the COVID-19 pandemic means that the result cannot be checked for the time being, because most of the worlds observatoriesincluding the VLTare not operational. It could be [confirmed or refuted] tomorrow, but the observatories are closed, says astronomer Guillem Anglada-Escud, who led the discovery of Proxima b in 2016 and was not involved in the new study. Time is running out for an immediate follow-up: in July Proxima Centauri will pass out of view behind our sun until February 2021.

So for now, the prospect of Proxima c having been seen for the first time remains an enticing but elusive possibility. Even if it proves to be a miragean astronomical false alarmthis potential detection is unlikely to dampen enthusiasm for further studies. Other teams will try again with upcoming instruments, more advanced than SPHERE, operating on supersized telescopes such as the E-ELT. But if the detection is real, which Gratton says he is two thirds confident about, it would be a historic initial glimpse of a planet orbiting the closest start to our own. If this is true, its very exciting, says Anglada-Escud.

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Astronomers May Have Captured the First Ever Image of Nearby Exoplanet Proxima C - Scientific American