Aurora Boreal En Alaska

En esta fotografía podemos apreciar la luz zodiacal, luz reflejada de las partículas de polvo interplanetario. A la derecha a la Vía Láctea y en medio la galaxia de Andrómeda.

Crédito: Jeff Dai

https://instagram.com/jeffdaiphoto

~Antares

Eclipse Solar Total 2020 desde Valcheta, Río negro en Argentina

Crédito: Pablo Barrios

Instagram.com/Pd.barrios

¡Aquí hay una increíble concepción de un artista, que representa la "Sky Crane" de la NASA mientras baja el rover Perseverance de Mars 2020 para un aterrizaje suave en la superficie del planeta rojo!

Crédito de representación: MAAS digital LLC, National Geographic Channel

Black Holes Dine on Stellar Treats!

See that tiny blob of light, circled in red? Doesn’t look like much, does it? But that blob represents a feast big enough to feed a black hole around 30 million times the mass of our Sun! Scientists call these kinds of stellar meals tidal disruption events, and they’re some of the most dramatic happenings in the cosmos.

Sometimes, an unlucky star strays too close to a black hole. The black hole’s gravity pulls on the star, causing it to stretch in one direction and squeeze in another. Then the star pulls apart into a stream of gas. This is a tidal disruption event. (If you’re worried about this happening to our Sun – don’t. The nearest black hole we know about is over 1,000 light-years away. And black holes aren’t wild space vacuums. They don’t go zipping around sucking up random stars and planets. So we’re pretty safe from tidal disruption events!)

The trailing part of the stream gets flung out of the system. The rest of the gas loops back around the black hole, forming a disk. The material circling in the disk slowly drifts inward toward the black hole’s event horizon, the point at which nothing – not even light – can escape. The black hole consumes the gas and dust in its disk over many years.

Sometimes the black hole only munches on a passing star – we call this a partial tidal disruption event. The star loses some of its gas, but its own gravity pulls it back into shape before it passes the black hole again. Eventually, the black hole will have nibbled away enough material that the star can’t reform and gets destroyed.

We study tidal disruptions, both the full feasts and the partial snacks, using many kinds of telescopes. Usually, these events are spotted by ground-based telescopes like the Zwicky Transient Facility and the All-Sky Automated Survey for Supernovae network.

They alert other ground- and space-based telescopes – like our Neil Gehrels Swift Observatory (illustrated above) and the European Space Agency’s XMM-Newton – to follow up and collect more data using different wavelengths, from visible light to X-rays. Even our planet-hunting Transiting Exoplanet Survey Satellite has observed a few of these destructive wonders!

We’re also studying disruptions using multimessenger astronomy, where scientists use the information carried by light, particles, and space-time ripples to learn more about cosmic objects and occurrences.

But tidal disruptions are super rare. They only happen once every 10,000 to 100,000 years in a galaxy the size of our own Milky Way. Astronomers have only observed a few dozen events so far. By comparison, supernovae – the explosive deaths of stars – happen every 100 years or so in a galaxy like ours.

That’s why scientists make their own tidal disruptions using supercomputers, like the ones shown in the video here. Supercomputers allow researchers to build realistic models of stars. They can also include all of the physical effects they’d experience whipping ‘round a black hole, even those from Einstein’s theory of general relativity. They can alter features like how close the stars get and how massive the black holes are to see how it affects what happens to the stars. These simulations will help astronomers build better pictures of the events they observe in the night sky.

Keep up with what’s happening in the universe and how we study it by following NASA Universe on Twitter and Facebook.

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What’s Inside a ‘Dead’ Star?

Matter makes up all the stuff we can see in the universe, from pencils to people to planets. But there’s still a lot we don’t understand about it! For example: How does matter work when it’s about to become a black hole? We can’t learn anything about matter after it becomes a black hole, because it’s hidden behind the event horizon, the point of no return. So we turn to something we can study – the incredibly dense matter inside a neutron star, the leftover of an exploded massive star that wasn’t quite big enough to turn into a black hole.

Our Neutron star Interior Composition Explorer, or NICER, is an X-ray telescope perched on the International Space Station. NICER was designed to study and measure the sizes and masses of neutron stars to help us learn more about what might be going on in their mysterious cores.

When a star many times the mass of our Sun runs out of fuel, it collapses under its own weight and then bursts into a supernova. What’s left behind depends on the star’s initial mass. Heavier stars (around 25 times the Sun’s mass or more) leave behind black holes. Lighter ones (between about eight and 25 times the Sun’s mass) leave behind neutron stars.

Neutron stars pack more mass than the Sun into a sphere about as wide as New York City’s Manhattan Island is long. Just one teaspoon of neutron star matter would weigh as much as Mount Everest, the highest mountain on Earth!

These objects have a lot of cool physics going on. They can spin faster than blender blades, and they have powerful magnetic fields. In fact, neutron stars are the strongest magnets in the universe! The magnetic fields can rip particles off the star’s surface and then smack them down on another part of the star. The constant bombardment creates hot spots at the magnetic poles. When the star rotates, the hot spots swing in and out of our view like the beams of a lighthouse.

Neutron stars are so dense that they warp nearby space-time, like a bowling ball resting on a trampoline. The warping effect is so strong that it can redirect light from the star’s far side into our view. This has the odd effect of making the star look bigger than it really is!

NICER uses all the cool physics happening on and around neutron stars to learn more about what’s happening inside the star, where matter lingers on the threshold of becoming a black hole. (We should mention that NICER also studies black holes!)

Scientists think neutron stars are layered a bit like a golf ball. At the surface, there’s a really thin (just a couple centimeters high) atmosphere of hydrogen or helium. In the outer core, atoms have broken down into their building blocks – protons, neutrons, and electrons – and the immense pressure has squished most of the protons and electrons together to form a sea of mostly neutrons.

But what’s going on in the inner core? Physicists have lots of theories. In some traditional models, scientists suggested the stars were neutrons all the way down. Others proposed that neutrons break down into their own building blocks, called quarks. And then some suggest that those quarks could recombine to form new types of particles that aren’t neutrons!

NICER is helping us figure things out by measuring the sizes and masses of neutron stars. Scientists use those numbers to calculate the stars’ density, which tells us how squeezable matter is!

Let’s say you have what scientists think of as a typical neutron star, one weighing about 1.4 times the Sun’s mass. If you measure the size of the star, and it’s big, then that might mean it contains more whole neutrons. If instead it’s small, then that might mean the neutrons have broken down into quarks. The tinier pieces can be packed together more tightly.

NICER has now measured the sizes of two neutron stars, called PSR J0030+0451 and PSR J0740+6620, or J0030 and J0740 for short.

J0030 is about 1.4 times the Sun’s mass and 16 miles across. (It also taught us that neutron star hot spots might not always be where we thought.) J0740 is about 2.1 times the Sun’s mass and is also about 16 miles across. So J0740 has about 50% more mass than J0030 but is about the same size! Which tells us that the matter in neutron stars is less squeezable than some scientists predicted. (Remember, some physicists suggest that the added mass would crush all the neutrons and make a smaller star.) And J0740’s mass and size together challenge models where the star is neutrons all the way down.

So what’s in the heart of a neutron star? We’re still not sure. Scientists will have to use NICER’s observations to develop new models, perhaps where the cores of neutron stars contain a mix of both neutrons and weirder matter, like quarks. We’ll have to keep measuring neutron stars to learn more!

Keep up with other exciting announcements about our universe by following NASA Universe on Twitter and Facebook.

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Luna

Cámara digital compacta Canon Powershot Sx60hs X85 zoom, sin telescopio.

Crédito: Hidehiko Akazawa

Eclipse Total Solar 2010

Crédito: Andreas Möller

La Residencia La Silla ofrece unas vistas bastantes espectaculares del cielo nocturno. Sobre la residencia los distintos observatorios de La Silla puntean el cerro, culminando con el NTT (Telescopio de Nueva Tecnología) y el telescopio de 3.6 metros sentados encima del resto.

Crédito: Utah Astrophotography (Bryony Richards & Eric Benedetti).

https://instagram.com/utahastrophotography

~Antares