Daily Archives: February 11, 2022

ONEILL A course for anyone with an interest in the night (or daytime) sky will be offered by Northeast Community College in ONeill later this month.

The class, Astronomy: Beginning Observational Astronomy/Atmospheric Optics (HORC 5110/22S and CRN No. 70214) meets Monday, Feb. 28, from 6:30 to 8:30 p.m., in Room 132 in the Northeast Community College Extended Campus in ONeill, 505 East Highway 20.

With instructor Mark Urwiller, participants will explore concepts of celestial mechanics, types of objects to view day or night and equipment that can be used to view the sky. The class will help participants enjoy the sky without special equipment, use the equipment they already have or select equipment to buy if they want to take their interest to the next level.

Participants are asked to bring a laptop, tablet or smartphone, if available. They are not required.

Pre-registration is required. To register, call Northeast Community College in O'Neill at 402-336-3590.

Read more:

Beginning astronomy course to be offered at Northeast in O'Neill - Norfolk Daily News

An artists rendition of a red supergiant star transitioning into a Type II supernova, emitting a violent eruption of radiation and gas on its dying breath before collapsing and exploding. Credit: W. M. Keck Observatory/Adam Makarenko

Its another first for astronomy.

For the first time, a team of astronomers have imaged in real-time as a red supergiant star reached the end of its life. They watched as the star convulsed in its death throes before finally exploding as a supernova.

And their observations contradict previous thinking into how red supergiants behave before they blow up.

An artists impression of a red supergiant star in the final year of its life emitting a tumultuous cloud of gas. This suggests at least some of these stars undergo significant internal changes before going supernova. Credit: W.M. Keck Observatory/Adam Makarenko

A team of astronomers watched the drama unfold through the eyes of two observatories in Hawaii: Pan-STARRS on Haleakala, Maui, and the W. M. Keck Observatory on Maunakea, Hawaii Island. Their observations were part of the Young Supernova Experiment (YSE) transient survey. They watched the supernova explosion, named SN 2020tlf, during the final 130 days leading up to its detonation.

For the first time, we watched a red supergiant star explode! Wynn Jacobson-Galn, UC Berkeley

The title of the paper presenting the discovery is Final Moments. I. Precursor Emission, Envelope Inflation, and Enhanced Mass Loss Preceding the Luminous Type II Supernova 2020tlf. The paper is published in The Astrophysical Journal and the lead author is Wynn Jacobson-Galn, an NSF Graduate Research Fellow at UC Berkeley.

This is a breakthrough in our understanding of what massive stars do moments before they die, said Jacobson-Galn, in a press release. Direct detection of pre-supernova activity in a red supergiant star has never been observed before in an ordinary Type II supernova. For the first time, we watched a red supergiant star explode!

Its like watching a ticking time-bomb. Raffaella Margutti, UC Berkeley

The discovery dates back to the Summer of 2020. At that time, the progenitor star experienced a dramatic rise in luminosity. Pan-STARRS detected that brightening, and when Fall came around the star exploded as SN 2020tlf. The supernova is a Type II supernova, where a massive star experiences a rapid collapse and then explodes.

This video is an artists rendition of the red supergiant star transitioning into a Type II supernova, emitting a violent eruption of radiation and gas on its dying breath before collapsing and exploding. Credit: W. M. Keck Observatory/Adam Makarenko

The team used the Keck Observatorys Low-Resolution Imaging Spectrometer (LRIS) to capture the supernovas first spectrum. The LRIS data showed circumstellar material around the star when it exploded. That material is likely what Pan-STARRS saw the star ejecting in the summer before it exploded.

Keck was instrumental in providing direct evidence of a massive star transitioning into a supernova explosion, said senior author Raffaella Margutti, an associate professor of astronomy at UC Berkeley. Its like watching a ticking time bomb. Weve never confirmed such violent activity in a dying red supergiant star where we see it produce such a luminous emission, then collapse and combust, until now.

This figure from the study shows the supernova pre- and post-explosion. The top panel shows the total of all electromagnetic radiation emitted by the event across all wavelengths, in green. The middle panel shows black-body temperatures in red, and the bottom panel shows the radii in blue. Image Credit: Jacobson-Galn et al, 2022

After the explosion, the team turned to other Keck instruments to continue their observations. Data from the DEep Imaging and Multi-Object Spectrograph (DEIMOS) and Near Infrared Echellette Spectrograph (NIRES) showed that the progenitor star was 10 times more massive than the Sun. The star is in the NGC 5731 galaxy about 120 million light-years away.

The teams observations led to some new insight into Type II supernovae and their progenitor stars. Prior to these observations, nobody had seen a red supergiant display such a spike in luminosity and undergo such powerful eruptions before exploding. They were much more placid in their final days as if they accepted their fates.

Red supergiant stars eject material prior to core collapse. But that material ejection takes place on much longer timescales than SN 2020tlf. This supernova emitted circumstellar material (CSM) for 130 days prior to collapse, and that makes it a bit of a puzzle. The bright flash prior to the stars explosion is somehow related to the ejected CSM, but the team of researchers isnt certain how they all interacted.

Artists impression of a Type II supernova explosion which involves the destruction of a massive supergiant star. Credit: ESO

The significant variability in the star leading up to collapse is puzzling. The powerful burst of light coming from the star prior to exploding suggests that something unknown happens in its internal structure. Whatever those changes are, they result in a mammoth ejection of gas before the star collapsed and exploded.

In their paper, the authors discuss what may have caused the ejection of gas. One possibility is wave-driven mass loss, which occurs in the late stages of stellar evolution. It occurs when the excitation of gravitational waves by oxygen or neon burning in the final years before SN can allow for the injection of energy into the outer stellar layers, resulting in an inflated envelope and/or eruptive mass-loss episodes, they write. But current wave-driven models dont match the progenitor stars ejection of gas. Theyre consistent with the progenitor stars radius in its last 130 days, but not consistent with the burst of luminosity.

In the conclusion of their paper, the authors sum things up succinctly. Given the progenitor mass range derived from nebular spectra, it is likely that the enhanced mass loss and precursor emission are the results of instabilities deeply rooted in the stellar interior, most likely associated with the final nuclear burning stages. Energy deposition from either gravitational waves generated in neon/oxygen burning stages or a silicon flash in the progenitors final ?130 days could have ejected stellar material that was then detected in both pre-explosion flux and the early-time SN spectrum.

If theres one supernova that behaves like this, there must be more. The teams findings mean that surveys like the Young Supernova Experiment transient survey now have a way to find more of them in the future. If the survey finds more stars ejecting material like this one, then they know to keep an eye on it to see if it collapses and explodes.

I am most excited by all of the new unknowns that have been unlocked by this discovery, said Jacobson-Galn. Detecting more events like SN 2020tlf will dramatically impact how we define the final months of stellar evolution, uniting observers and theorists in the quest to solve the mystery of how massive stars spend the final moments of their lives.

Originally published on Universe Today.

For more on this research:

Read the original:

Astronomers Watch a Star Die and Then Explode as a Supernova For the Very First Time - SciTechDaily

We already knew the asteroid 130 Elektra was special. Astronomers previously discovered it had two moons, making it a rare triple asteroid system. Now a third moon may have been found, making it even more uncommon the first-known quadruple asteroid in the solar system.

Elektra was first discovered in 1873, orbiting in the asteroid belt between Mars and Jupiter. Oblong-shaped and 160 miles across on its longest side, it is a relatively large asteroid and completes an orbit of the sun every five years.

In 2003, the first moon was discovered orbiting Elektra, and in 2014 a second. The discoveries were interesting, but not unusual more than 150 asteroids are known to have one or two moons, in the same way planets can have moons that are gravitationally bound to them. Multiple moons can be found around large asteroids, said Bin Yang, an astronomer from the European Southern Observatory in Chile who discovered Elektras second moon. A NASA mission, DART, is on target to collide with one such asteroids moon later in the year.

But until now, an asteroid with three moons has eluded astronomers. Anthony Berdeu from the National Astronomical Research Institute of Thailand and colleagues used images from the Very Large Telescope (V.L.T.) in Chile to take a closer look at Elektra, and they found evidence for a previously hidden moon inside the orbits of the other two.

This is the first asteroid with three moons, Dr. Berdeu said. We are pretty confident. Its quite exciting.

Their results were published Tuesday in the journal Astronomy & Astrophysics.

At a paltry one mile across, the moon would be slightly smaller than its siblings at 1.2 and 3.7 miles across. It swings around Elektra once every 16 hours at a distance of only 220 miles. To an observer standing on the third moons surface, Elektra would loom large in the sky.

Dr. Berdeu says he was able to find the moon using a new algorithm to eke out its extremely faint light in images taken by the V.L.T. The data reduction techniques employed by the algorithm allowed for a sharper image of Elektra and its surroundings.

Dr. Yang, who was not involved in this paper, said that she and other astronomers had been trying to look for quadruple systems for a while, and that her team also saw tantalizing hints of this third moon in their studies of 130 Elektra. This discovery would be a very exciting result, she said, although further observations will be needed to confirm the moons existence.

Alan Fitzsimmons, an astronomer from Queens University Belfast who was also not involved in the paper, says the moons are most likely chunks of Elektra that were broken off in a collision when another object smashed into the asteroid in the past. They all look like theyre from the same material, he said.

Further study of this system could reveal the stability of such multi-moon asteroids. This third moons orbit is misaligned to the other two, something thats very strange, Dr. Berdeu said. Dr. Yang said that she thought the system was unstable and that the inner moons may eventually fall back onto Elektra.

It could also tell us more about the formation of multi-moon asteroids. This new finding will inspire modelers to look at asteroid impact formation, and try to set a limit on how many moons an impact can form, Dr. Yang said. How many moons can a system really sustain?

Further studies are expected to unearth more quadruple systems too. New telescopes, such as the Extremely Large Telescope currently being built in Chile, will have the observing power necessary to more easily spot these multi-moon asteroid systems.

And astronomers may not stop at quadruple asteroids. There is no limit to what we can find, Dr. Berdeu said. We expect to find more quadruple systems, and why not quintuple or sextuple.

Read the rest here:

The First Quadruple Asteroid: Astronomers Spot a Space Rock With 3 Moons - The New York Times

Home Lifestyle This $74K Astronomy Watch Aims to Liberate the Mind; Shows Earth, Sun, Moons Positions

Horologist Ulysse Nardin claims its Moonstruck design features reinvented mechanics that will reproduce the suns trajectory and lunar cycles in a simple-to-decrypt face. Hmm.

In a few words, the Blast Moonstruck is an elaborate analog watch. Through its combination of highly specialized intricacies, the astronomical watch provides wearers with info about the solar position, lunar phase, and, conveniently the time at a glance.

High-end wristwatches are nothing new. And the most sought-after iterations tend to be analog. Horology is a mechanistic art form that is incredibly complex, and, as a result, I find myself wedged halfway down any rabbit hole that Ive attempted on the subject.

So when I read the press release telling me that this bourgie idea of a ticker set in motion the primordial elements of the visible celestial mechanisms so that everyone can gain a poetic understanding, I was three things: very lost, very skeptical, and very, very curious.

Heres what I figured out. And, presumably, what you need to know.

Its makers boast the timepiece as a scientific representation of considerable oneiric potential (dreamlike I had to look that one up, too). According to the brand, the watchs solar and lunar indicators provide great leaders (but also sailors) with the information needed to predict the spring tides.

A top-down view with the North Pole at the center of the dial and a domed sapphire crystal make observers feel as if they are at the center of the cosmos, the Ulysse Nardin team says.

A three-dimensional sun begins its cycle at 12 oclock and an aventurine disk stands in as the night sky. That disk, by some magnificent gear train, plays out the moons phases and completes a full rotation every 24 hours.

Similarly, the sun completes its rotation along the Moonstrucks 18-carat rose gold outer bezel every 29.5 days.

Speaking of material makeup, the case comprises black ceramic and DLC titanium. Customers can choose from black alligator, black velvet, or black rubber straps. But as the saying goes, in for a penny, in for the full alligator leather.

A simple winding crown adjusts the time, and two rectangular buttons operate the dual-time setting function. See the full list of the tickers functions and specs below.

To learn more and place an order for the $73,900 Blast Moonstruck, head to ulysse-nardin.com.

Citizens Promaster series is legendary. Their solar-powered diver has been featured not once, but twice here on GearJunkie. So, when the makers of this fan-favorite announced that their latest model had sprouted legs and climbed out of the sea, we were immediately intrigued. Read more

Read more:

This $74K Astronomy Watch Aims to 'Liberate the Mind'; Shows Earth, Sun, Moon's Positions - GearJunkie

Laniakea Supercluster superimposed on orbits and surfaces of mass density. Credit: University of Hawaii

Everything in our universe moves, but the timescales needed to see motion are often vastly greater than human lifetimes. In a major new study, a team of astronomers from the University of Hawaii Institute for Astronomy (IfA), University of Maryland and University of Paris-Saclay has traced the movement of 10,000 galaxies and clusters of galaxies, the dominant congregations of matter, within 350 million light-years. Their motions are followed throughout a span of 11.5 billion years from the galaxies origins when the universe was only 1.5 billion-years-old, until today, at an age of more than 13 billion years.

The study has been accepted for publication in The Astrophysical Journal.

Using a mathematical technique called numerical action method, the team has computed these paths based on the present brightness and positions of galaxies, and their present motion away from us. The astronomers have factored in the physics of the Big Bang theory, including the idea that galaxies initially start out expanding from each other almost precisely at what is called the Hubble expansion rate. Throughout time, gravity alters galaxy motions, so they are not just moving apart as the universe expands, but are drawn together into filaments, walls and clusters, while also emptying out other regions that are now voids. Over the eons of time, galaxies typically deviate from pure Hubble rate expansion by millions of light-years over a billion years. In regions of high density, the galaxy orbits can become quite complicated and involve collisions and mergers.

Slice of local universe showing orbits that galaxies have followed in white and contours of regions of high density in shades of yellow-orange. Milky Way (near center) Great Attractor core of Laniakea Supercluster (left) Perseus-Pisces (right). Credit: University of Hawaii

We are bringing into focus the detailed formation history of large-scale mass structures in the universe by reverse engineering the gravitational interactions that created them, said Ed Shaya, Associate Research Scientist at the University of Maryland.

There are several particularly interesting vast regions of high matter and galaxy density the astronomers explore. One, which has been called the Great Attractor, is the core of the Laniakea Supercluster, an immense supercluster of galaxies containing our own Milky Way. Galaxies can be seen flowing toward a location within a nest of four rich clusters.

Milky Way Galaxy. Credit: Thomas Ciszewski

A second fascinating region is in the adjacent Perseus-Pisces filament of galaxies, which stretches for nearly a billion light-years and is one of the largest known structures in the universe. The vicinity of the Virgo Cluster, the closest large cluster, is also seen, and can be studied in detail because it is nearby.

For more than 30 years, astronomers have considered a Great Attractor to be the primary source of gravity that makes the whole region near us move with a high peculiar velocity relative to uniform cosmic expansion, but the nature of that source has been obscure, said R. Brent Tully, an astronomer at IfA who co-authored the study. Our orbit reconstructions have provided the first good look at this previously enigmatic region.

Across the entire expanse, the orbits can be projected into the future as well. The accelerating expansion of the universe dominates the overall picture, causing most galaxies to move apart. However, some coalescence and merging will continue in localized regions.

A video of the paths of galaxies in this vast region, starting from the epoch of early galaxy formation and continuing until the universe is almost twice as old can be viewed here. On the large scales depicted in this simulation, only a few major mergers, all in very dense regions, are seen to occur in the next 10 billion years.

The technical article is accompanied by four interactive models. and four videos:

Reference: Galaxy flows within 8,000 km/s from Numerical Action methods by Edward Shaya, R. Brent Tully, Daniel Pomarde and Alan Peel, Accepted, The Astrophysical Journal.DOI: 10.3847/1538-4357/ac4f66arXiv:2201.12315

The research team is composed of Shaya (University of Maryland), Tully (University of Hawaii), Daniel Pomarede (University of Paris-Saclay) and Alan Peel (University of Maryland).

Read more from the original source:

Astronomers Trace the Movement of 10,000 Galaxies Over the Last 11.5 Billion Years - SciTechDaily

When a massive star dies at the end of its life, the core collapses to form either a very dense neutron star or a black hole. At the same time, the outer layers of the star are explosively launched into space by the colossal energy generated in the core collapse. The blast wave is so powerful that the expanding debris lights up with as much energy as billions upon billions of times the energy emitted by the Sun, and in fact can outshine an entire galaxy.

A supernova is born. But not all supernovae are created equal.

Some are far more powerful than others. The description above is ridiculously oversimplified here's a somewhat more detail explanation, and more technical ones can easily be found online and changing conditions from star to star can change the way one explodes. It can depend on things like having a binary star companion or not, the mass of the star when it explodes, the mass it had when it was born, how much of its outer layers blow off before the explosion, and more.

Still, there are supernovae that are exceptional even in this bewildering variety of explosions, and they can be very hard to explain. One in particular stands out, and astronomers think they can now explain what happened.

On June 16, 2018, the Asteroid Terrestrial-impact Last Alert System detected a supernova in a galaxy roughly 200 million light years away. The naming convention for these events dubbed it AT2018cow, and because astronomers are dorks just like everyone else it was known thereafter as the COW.

Other observatories were alerted and started watching it as well, and as the data came in astronomers were surprised to see just how luminous this explosion was 100 billion times brighter than the Sun! This puts it in the rare class of superluminous supernovae, ones which are far more powerful than average.

But it also acted weirdly. It rose in brightness much faster than usual as well. Most supernovae take about two weeks before hitting peak luminosity, but this one rose in brightness by a factor of 100 in a single day. It also faded much more rapidly than typical supernovae as well. The COW's color in early days was blue, so this new type of event was called a Fast Blue Optical Transient, or FBOT. I wrote a synopsis of all this not long after it happened, if you want the details.

In the years since there has been a lot of work trying to figure out how to make a star explode like this, with limited success. Ideas have included the birth of a super-magnetized neutron star called a magnetar, or a white dwarf torn apart by a black hole (!!), and more. But now a team of astronomers thinks they have the answer (link to paper).

Sometimes, in the millennia or even years before the final explosion, massive stars can blow a lot of their outer layers away. Sometimes it's slow Betelgeuse, for example, blows out a slow dense wind of matter and sometimes it's more violent. This material surrounds the pre-supernova star so it's called the circumstellar matter.

We have physical models for how the interiors of such stars behave, equations that can be solved to understand what's happening deep inside a star. These can then be used to see what happens when the star explodes, and try to match the energies emitted to what's actually observed.

The astronomers modeled the COW as a very massive star, one born with a whopping 80 times the mass of the Sun. That's huge, and it's very rare for stars to get this big. Such a star loses much of its hydrogen outer layers during its life, blowing them away to great distance.

What's left is a still-crushingly-hefty core 42 times the Sun's mass that's mostly helium. At this point the star's core is fusing ever-heavier elements in its very center, layered like an onion. Some of that helium on the surface is blown into space as well, and the best model fit to the observations indicates about half a solar mass was surrounding the core when it blew up. That's less than in some cases, but still about 150,000 times the mass of the Earth.

The core is so massive a very bad thing happened deep inside it. When it started fusing oxygen into silicon the reaction is so energetic it produces super-high-energy gamma rays, the highest energy form of light. These gamma rays in part support the core against its own immense gravity, heating the interior enough to keep it inflated.

But gamma rays at these energies are unstable. They can spontaneously convert themselves into matter, an electron and anti-electron, a process called pair production. This steals away energy supporting the core, so gravity squeezes it, making it smaller. The temperature goes up, the core expands a bit, and finds equilibrium again. Until, that is, gamma rays start converting again, and the process repeats. This causes the core to pulsate, which helps it blow material off its surface.

At this point its life can now be measured in days, maybe weeks. Helium blows off its surface, and the pulsations get bigger and bigger, until finally as it always does in the end gravity wins. The core collapses, the temperature screams way up, and it explodes.

The total energy released in just a few days is truly staggering, as much as the Sun gives off over its entire 10 billion year lifetime. The blast wave from this titanic explosion slams into the previously ejected helium, lighting it up. If there had been a lot of this material around the star, more than the mass of the Sun, it would've taken many days to light it up and even longer for it to fade. But because it was only half a solar mass it brightened and faded rapidly.

The astronomers find that their model reproduces that rapid change in brightness of the first 20 days of the supernova pretty well. After that, the usual sort of supernova models work, with about 0.6 solar masses of radioactive nickel created in the nuclear furnace decaying into cobalt, generating so much light it explains the supernova's brightness thereafter.

Interestingly, they find that the total energy of the explosion doesn't affect the brightness over time what astronomers call a light curve very much at all, but what really dominates here is the material around the star, its shape, and its density. That's the key to understanding these fast supernovae.

For truly massive stars, over 100 times the mass of the Sun, the core explosion is so violent it tears itself apart completely, leaving nothing behind. In this case it may have left a black hole or a magnetar, and material falling back on this object may explain the brightness many weeks after the explosion. But the first few weeks are dominated by the circumstellar matter.

Now that these models exist it'll be interesting to see how they apply to any future such FBOT supernovae. Fitting a specific case is one thing, but generalizing it to be able to explain others is a strong indication that they're doing something right.

See the article here:

Bad Astronomy | The supernova AT2018cow may finally be explained | SYFY WIRE - SYFY WIRE