When Dead Stars Collide!
When Dead Stars Collide!
Gravity has been making waves - literally. Earlier this month, the Nobel Prize in Physics was awarded for the first direct detection of gravitational waves two years ago. But astronomers just announced another huge advance in the field of gravitational waves - for the first time, we’ve observed light and gravitational waves from the same source.
There was a pair of orbiting neutron stars in a galaxy (called NGC 4993). Neutron stars are the crushed leftover cores of massive stars (stars more than 8 times the mass of our sun) that long ago exploded as supernovas. There are many such pairs of binaries in this galaxy, and in all the galaxies we can see, but something special was about to happen to this particular pair.
Each time these neutron stars orbited, they would lose a teeny bit of gravitational energy to gravitational waves. Gravitational waves are disturbances in space-time - the very fabric of the universe - that travel at the speed of light. The waves are emitted by any mass that is changing speed or direction, like this pair of orbiting neutron stars. However, the gravitational waves are very faint unless the neutron stars are very close and orbiting around each other very fast.
As luck would have it, the teeny energy loss caused the two neutron stars to get a teeny bit closer to each other and orbit a teeny bit faster. After hundreds of millions of years, all those teeny bits added up, and the neutron stars were *very* close. So close that … BOOM! … they collided. And we witnessed it on Earth on August 17, 2017.
Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet
A couple of very cool things happened in that collision - and we expect they happen in all such neutron star collisions. Just before the neutron stars collided, the gravitational waves were strong enough and at just the right frequency that the National Science Foundation (NSF)’s Laser Interferometer Gravitational-Wave Observatory (LIGO) and European Gravitational Observatory’s Virgo could detect them. Just after the collision, those waves quickly faded out because there are no longer two things orbiting around each other!
LIGO is a ground-based detector waiting for gravitational waves to pass through its facilities on Earth. When it is active, it can detect them from almost anywhere in space.
The other thing that happened was what we call a gamma-ray burst. When they get very close, the neutron stars break apart and create a spectacular, but short, explosion. For a couple of seconds, our Fermi Gamma-ray Telescope saw gamma-rays from that explosion. Fermi’s Gamma-ray Burst Monitor is one of our eyes on the sky, looking out for such bursts of gamma-rays that scientists want to catch as soon as they’re happening.
And those gamma-rays came just 1.7 seconds after the gravitational wave signal. The galaxy this occurred in is 130 million light-years away, so the light and gravitational waves were traveling for 130 million years before we detected them.
After that initial burst of gamma-rays, the debris from the explosion continued to glow, fading as it expanded outward. Our Swift, Hubble, Chandra and Spitzer telescopes, along with a number of ground-based observers, were poised to look at this afterglow from the explosion in ultraviolet, optical, X-ray and infrared light. Such coordination between satellites is something that we’ve been doing with our international partners for decades, so we catch events like this one as quickly as possible and in as many wavelengths as possible.
Astronomers have thought that neutron star mergers were the cause of one type of gamma-ray burst - a short gamma-ray burst, like the one they observed on August 17. It wasn’t until we could combine the data from our satellites with the information from LIGO/Virgo that we could confirm this directly.
This event begins a new chapter in astronomy. For centuries, light was the only way we could learn about our universe. Now, we’ve opened up a whole new window into the study of neutron stars and black holes. This means we can see things we could not detect before.
The first LIGO detection was of a pair of merging black holes. Mergers like that may be happening as often as once a month across the universe, but they do not produce much light because there’s little to nothing left around the black hole to emit light. In that case, gravitational waves were the only way to detect the merger.
Image Credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)
The neutron star merger, though, has plenty of material to emit light. By combining different kinds of light with gravitational waves, we are learning how matter behaves in the most extreme environments. We are learning more about how the gravitational wave information fits with what we already know from light - and in the process we’re solving some long-standing mysteries!
Want to know more? Get more information HERE.
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More Posts from Science-child and Others
Gravitational Waves in the Space-Time Continuum
Einstein's Theories of Relativity
Einstein has two theories of relativity. The first is The Theory of Special Relativity (1905). This is a theory of mechanics that correctly describes the motions of objects moving near the speed of light. This theory predicts that mass increases with velocity. The equation is E=MC^2 or Energy = Mass × Speed of Light ^2.
In 1916, Einstein proposed the Theory of General Relativity, which generalized his Theory of Special Relativity and had the first predictions of gravitational waves. It implied a few things.
Space-Time is a 4-Dimensional continuum.
Principle of equivalence of gravitational and inertial mass.
This suggests that Mass-Energy distorts the fabric of space-time in a predictable way (gravitational waves). It also implies
Strong gravitational force makes time slow down.
Light is altered by gravity
Gravity in strong gravitational fields will no longer obey Newton's Inverse-Square Law.
What is Newton's Inverse-Square Law?
Newton's Inverse-Square Law suggests that the force of gravity between any two objects is inversely proportional to the square of the separation distance between the two centers.
Stephen Hawking's Theory of Everything
Stephen Hawking's Theory of Everything is the solution to Einstein's equation in his Theory of General Relativity. It says that the mass density of the universe exceeds the critical density.
Critical Density: amount of mass needed to make a universe adopt a flat geometry.
This theory states that when the universe gets too big it will crash back into its center in a "Big Crunch" creating giant black hole. The energy from this "Big Crunch" will rebound and create a new "Big Bang".
Big Crunch: hypothetical scenario for the end of the known universe. The expansion of the universe will reverse and collapse on itself. The energy generated will create a new Big Bang, creating a new universe.
Big Bang: Matter will expand from a single point from a state of high density and matter. This will mark the birth of a new universe.
Basic Facts about Gravitational Waves
Invisible "ripples" in the Space-Time Continuum
Travel at the speed of light
186,000 miles per second / 299,337.984 Kilometers per second
11,160,000 miles per minute / 17,960,279.04 Kilometers per minute
669,600,000 miles per hour / 1,077,616,742.4 Kilometers per hour
There are four (4) defined categories
Continuous
Stochastic
Burst
Compact Binary Inspiral
What is LIGO?
The first proof of the existence of gravitational waves came in 1974. 20+ years after Einstein's death.
The first physical proof came in 2015, 100 years after his theory was published. The waves were detected by LIGO.
LIGO- Laser Interferometer Gravitational-Wave Observatory
The waves detected in 2015 came from 2 black holes that collided 1.3 billion years ago in the constellation Hydra. 1.3 billion years ago multicellular life was just beginning to spread on Earth, it was before the time of the dinosaurs!
Continuous Gravitational Waves
Produced by a single spinning massive object.
Caused by imperfections on the surface.
The spin rate of the object is constant. The waves are come at a continuous frequency.
Stochastic Gravitational Waves
Smalles waves
Hardest to detect
Possibly caused by remnants of gravitational radiation left over from the Big Bang
Could possibly allow us to look at the history of the Universe.
Small waves from every direction mixed together.
Burst Gravitational Waves
Never been detected.
Like ever.
Never ever.
Not once.
Nope
No
N E V E R
We don't know anything about them.
If we learn about them they could reveal the greatest revolutionary information about the universe.
Compact Binary Inspiral Gravitational Waves
All waves detected by LIGO fall into this category.
Produced by orbiting pairs of massive and dense objects. (Neutron Stars, Black Holes)
Three (3) subclasses
Binary Neutron Star (BNS) // Two (2) Neutron Stars colliding
Binary Black Hole (BBH) // Two (2) Black Holes colliding
Neutron Star- Black Hole Binary (NSBH) // A black hole and a neutron star colliding
Each subclass creates its own unique wave pattern.
Waves are all caused by the smae mechanism called an "inspiral".
Occur over millions of years.
Over eons the objects orbit closer together.
The closer they get, the faster they spin.
Sources Used:
On The Shoulders Of Giants by Stephen Hawking
Oxford Astronomy Encyclopedia
@watch-out-idiot-passing-through @nasa
what is the biggest challenge in the preparation of such a mission and how do you handle it?
Hubble’s Guide to Viewing Deep Fields
They say a picture is worth a thousand words, but no images have left a greater impact on our understanding of the universe quite like the Hubble Space Telescope’s deep fields. Like time machines, these iconic images transport humanity billions of light-years back in time, offering a glimpse into the early universe and insight into galaxy evolution!
You’ve probably seen these images before, but what exactly do we see within them? Deep field images are basically core samples of our universe. By peering into a small portion of the night sky, we embark on a journey through space and time as thousands of galaxies appear before our very eyes.
So, how can a telescope the size of a school bus orbiting 340 miles above Earth uncover these mind-boggling galactic masterpieces? We’re here to break it down. Here’s Hubble’s step-by-step guide to viewing deep fields:
Step 1: Aim at the darkness
Believe it or not, capturing the light of a thousand galaxies actually begins in the dark. To observe extremely faint galaxies in the farthest corners of the cosmos, we need minimal light interference from nearby stars and other celestial objects. The key is to point Hubble’s camera at a dark patch of sky, away from the outer-edge glow of our own galaxy and removed from the path of our planet, the Sun, or the Moon. This “empty” black canvas of space will eventually transform into a stunning cosmic mosaic of galaxies.
The first deep field image was captured in 1995. In order to see far beyond nearby galaxies, Hubble’s camera focused on a relatively empty patch of sky within the constellation Ursa Major. The results were this step-shaped image, an extraordinary display of nearly 3,000 galaxies spread across billions of light-years, featuring some of the earliest galaxies to emerge shortly after the big bang.
Step 2: Take it all in
The universe is vast, and peering back billions of years takes time. Compared to Hubble’s typical exposure time of a few hours, deep fields can require hundreds of hours of exposure over several days. Patience is key. Capturing and combining several separate exposures allows astronomers to assemble a comprehensive core slice of our universe, providing key information about galaxy formation and evolution. Plus, by combining exposures from different wavelengths of light, astronomers are able to better understand galaxy distances, ages, and compositions.
The Hubble Ultra Deep Field is the deepest visible-light portrait of our universe. This astonishing display of nearly 10,000 galaxies was imaged over the course of 400 Hubble orbits around Earth, with a total of 800 exposures captured over 11.3 days.
Step 3: Go beyond what’s visible
The ability to see across billions of light-years and observe the farthest known galaxies in our universe requires access to wavelengths beyond those visible to the human eye. The universe is expanding and light from distant galaxies is stretched far across space, taking a long time to reach us here on Earth. This phenomenon, known as “redshift,” causes longer wavelengths of light to appear redder the farther they have to travel through space. Far enough away, and the wavelengths will be stretched into infrared light. This is where Hubble’s infrared vision comes in handy. Infrared light allows us to observe light from some of the earliest galaxies in our universe and better understand the history of galaxy formation over time.
In 2009, Hubble observed the Ultra Deep Field in the infrared. Using the Near Infrared Camera and Multi-Object Spectrometer, astronomers gathered one of the deepest core samples of our universe and captured some of the most distant galaxies ever observed.
Step 4: Use your time machine
Apart from their remarkable beauty and impressive imagery, deep field images are packed with information, offering astronomers a cosmic history lesson billions of years back in time within a single portrait. Since light from distant galaxies takes time to reach us, these images allow astronomers to travel through time and observe these galaxies as they appear at various stages in their development. By observing Hubble’s deep field images, we can begin to discover the questions we’ve yet to ask about our universe.
Credit: NASA, ESA, R. Bouwens and G. Illingworth (University of California, Santa Cruz)
Hubble’s deep field images observe galaxies that emerged as far back as the big bang. This image of the Hubble Ultra Deep Field showcases 28 of over 500 early galaxies from when the universe was less than one billion years old. The light from these galaxies represent different stages in their evolution as their light travels through space to reach us.
Step 5: Expand the cosmic frontier
Hubble’s deep fields have opened a window to a small portion of our vast universe, and future space missions will take this deep field legacy even further. With advancements in technologies and scientific instruments, we will soon have the ability to further uncover the unimaginable.
Slated for launch in late 2021, NASA’s James Webb Space Telescope will offer a new lens to our universe with its impressive infrared capabilities. Relying largely on the telescope’s mid-infrared instrument, Webb will further study portions of the Hubble deep field images in greater detail, pushing the boundaries of the cosmic frontier even further.
And there you have it, Hubble’s guide to unlocking the secrets of the cosmos! To this day, deep field images remain fundamental building blocks for studying galaxy formation and deepening not only our understanding of the universe, but our place within it as well.
Still curious about Hubble Deep Fields? Explore more and follow along on Twitter, Facebook, and Instagram with #DeepFieldWeek!
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"If I have seen farther, it is by standing on the shoulders of giants."
-Isaac Newton-
February 5, 1676
Decoding Nebulae
We can agree that nebulae are some of the most majestic-looking objects in the universe. But what are they exactly? Nebulae are giant clouds of gas and dust in space. They’re commonly associated with two parts of the life cycle of stars: First, they can be nurseries forming new baby stars. Second, expanding clouds of gas and dust can mark where stars have died.
Not all nebulae are alike, and their different appearances tell us what's happening around them. Since not all nebulae emit light of their own, there are different ways that the clouds of gas and dust reveal themselves. Some nebulae scatter the light of stars hiding in or near them. These are called reflection nebulae and are a bit like seeing a street lamp illuminate the fog around it.
In another type, called emission nebulae, stars heat up the clouds of gas, whose chemicals respond by glowing in different colors. Think of it like a neon sign hanging in a shop window!
Finally there are nebulae with dust so thick that we’re unable to see the visible light from young stars shine through it. These are called dark nebulae.
Our missions help us see nebulae and identify the different elements that oftentimes light them up.
The Hubble Space Telescope is able to observe the cosmos in multiple wavelengths of light, ranging from ultraviolet, visible, and near-infrared. Hubble peered at the iconic Eagle Nebula in visible and infrared light, revealing these grand spires of dust and countless stars within and around them.
The Chandra X-ray Observatory studies the universe in X-ray light! The spacecraft is helping scientists see features within nebulae that might otherwise be hidden by gas and dust when viewed in longer wavelengths like visible and infrared light. In the Crab Nebula, Chandra sees high-energy X-rays from a pulsar (a type of rapidly spinning neutron star, which is the crushed, city-sized core of a star that exploded as a supernova).
The James Webb Space Telescope will primarily observe the infrared universe. With Webb, scientists will peer deep into clouds of dust and gas to study how stars and planetary systems form.
The Spitzer Space Telescope studied the cosmos for over 16 years before retiring in 2020. With the help of its detectors, Spitzer revealed unknown materials hiding in nebulae — like oddly-shaped molecules and soot-like materials, which were found in the California Nebula.
Studying nebulae helps scientists understand the life cycle of stars. Did you know our Sun got its start in a stellar nursery? Over 4.5 billion years ago, some gas and dust in a nebula clumped together due to gravity, and a baby Sun was born. The process to form a baby star itself can take a million years or more!
After billions more years, our Sun will eventually puff into a huge red giant star before leaving behind a beautiful planetary nebula (so-called because astronomers looking through early telescopes thought they resembled planets), along with a small, dense object called a white dwarf that will cool down very slowly. In fact, we don’t think the universe is old enough yet for any white dwarfs to have cooled down completely.
Since the Sun will live so much longer than us, scientists can't observe its whole life cycle directly ... but they can study tons of other stars and nebulae at different phases of their lives and draw conclusions about where our Sun came from and where it's headed. While studying nebulae, we’re seeing the past, present, and future of our Sun and trillions of others like it in the cosmos.
To keep up with the most recent cosmic news, follow NASA Universe on Twitter and Facebook.
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Meet the Artemis Team Returning Humans to the Moon
We. Are. Going 🌙
Today, we introduced the eighteen NASA Astronauts forming the Artemis team. Together, they’ll use their diverse range of backgrounds, expertise, and experience to pave the way for humans to return to the Moon, to stay.
Meet the heroes of the future who’ll carry us back to the Moon and beyond - the Artemis generation.
Joe Acaba
Fun fact: Joe is a veteran of the U.S. Peace Corps! Get to know Joe personally with this video –> Watch HERE.
Kayla Barron
Fun fact: Kayla got her start in public service through serving in the U.S. Navy. Get to know Kayla personally with this video –> Watch HERE.
Raja Chari
Fun fact: Raja’s nickname is “Grinder,” and he comes from a test pilot background. Get to know Raja personally with this video –> Watch HERE.
Jessica Watkins
Fun fact: Jessica is a rugby national champion winner and geologist. Get to know Jessica personally with this video –> Watch HERE.
Matthew Dominick
Fun fact: Matthew sums himself up as a father, a husband and an explorer. Get to know Matthew personally with this video –> Watch HERE.
Jasmin Moghbeli
Fun fact: Jasmin says she still wakes up every morning and it feels like a “pinch me moment” to think she’s actually an astronaut right now. Get to know Jasmin personally with this video –> Watch HERE.
Victor Glover
Fun fact: Victor’s dream is to work on the surface of the Moon. Get to know Victor personally with this video –> Watch HERE.
Jessica Meir
Fun fact: Jessica was five years old when she knew she wanted to be an astronaut. Get to know Jessica personally with this video –> Watch HERE.
Woody Hoburg
Fun fact: Woody used to spend summers away from graduate school working search and rescue in Yosemite National Park. Get to know Woody personally with this video –> Watch HERE.
Anne McClain
Fun fact: Anne is a West Point alumni who describes herself as an impractical dreamer. Get to know Anne personally with this video –> Watch HERE.
Jonny Kim
Fun fact: Jonny is also a U.S. Navy SEAL with a medical degree from Harvard. Get to know Jonny personally with this video –> Watch HERE.
Nicole Mann
Fun fact: Nicole is a U.S. Lieutenant Colonel in the Marine Corps! Get to know Nicole personally with this video –> Watch HERE.
Kjell Lindgren
Fun fact: Kjell was a flight surgeon, a physician who takes care of astronauts, before applying to be an astronaut himself! Get to know Kjell personally with this video –> Watch HERE.
Christina Koch
Fun fact: Christina set a record for the longest single spaceflight by a woman with a total of 328 days in space. Get to know Christina personally with this video –> Watch HERE.
Frank Rubio
Fun fact: Frank was a Black Hawk helicopter pilot in the U.S. Army and family medical physician. Get to know Frank personally with this video –> Watch HERE.
Stephanie Wilson
Fun fact: Stephanie was the voice in Mission Control leading our NASA Astronauts for the all-woman spacewalk last year. Get to know Stephanie personally with this video –> Watch HERE.
Scott Tingle
Fun fact: Scott said he wanted to be an astronaut in a high school class and the students laughed – look at him now. Get to know Scott personally with this video –> Watch HERE.
Kate Rubins
Fun fact: Kate is actually IN space right now, so she will have to get her official portrait when she comes home! She is also the first person to sequence DNA in space. Get to know Kate personally with this video –> Watch HERE. Stay up to date with our Artemis program and return to the Moon by following NASA Artemis on Twitter, Facebook and Instagram.
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5 Out of this World Experiments Awaiting Crew-1 Space Scientists
NASA astronauts Shannon Walker, Victor Glover, and Mike Hopkins, and JAXA (Japan Aerospace Exploration Agency) astronaut Soichi Noguchi embark on a historic mission on November 14, 2020 aboard the Crew Dragon. NASA’s Crew-1 mission marks the first certified crew rotation flight to the International Space Station. During their 6-month stay on orbit, these crew members will don their science caps and complete experiments in microgravity. Check out five out of this world experiments you can expect to see these space scientists working on during Expedition 64.
1. Space Gardening
The Crew-1 astronauts will become space farmers with the responsibility of tending to the rad(ish) garden located in a facility known as the Advanced Plant Habitat (APH). Researchers are investigating radishes in the Plant Habitat-02 experiment as a candidate crop for spaceflight applications to supplement food sources for astronauts. Radishes have the benefits of high nutritional content and quick growth rates, making these veggies an intriguing option for future space farmers on longer missions to the Moon or Mars.
2. Micro Miners
Microbes can seemingly do it all, including digging up the dirt (so to speak). The BioAsteroid investigation looks at the ability of bacteria to break down rock. Future space explorers could use this process for extracting elements from planetary surfaces and refining regolith, the type of soil found on the moon, into usable compounds. To sum it up, these microbial miners rock.
3. Cooler Exploration Spacesuits
The iconic spacesuits used to walk on the moon and perform spacewalks on orbit are getting an upgrade. The next generation spacesuit, the Exploration Extravehicular Mobility Unit (xEMU), will be even cooler than before, both in looks and in terms of ability to regulate astronaut body temperature. The Spacesuit Evaporation Rejection Flight Experiment (SERFE) experiment is a technology demonstration being performed on station to look at the efficiency of multiple components in the xEMU responsible for thermal regulation, evaporation processes, and preventing corrosion of the spacesuits.
4. Chips in Space
Crew-1 can expect to get a delivery of many types of chips during their mission. We aren’t referring to the chips you would find in your pantry. Rather, Tissue Chips in Space is an initiative sponsored by the National Institutes of Health to study 3D organ-like constructs on a small, compact devices in microgravity. Organ on a chip technology allows for the study of disease processes and potential therapeutics in a rapid manner. During Expedition 64, investigations utilizing organ on a chip technology will include studies on muscle loss, lung function, and the blood brain barrier – all on devices the size of a USB flashdrive.
5. The Rhythm of Life
Circadian rhythm, otherwise known as our “internal clock,” dictates our sleep-wake cycles and influences cognition. Fruit flies are hitching a ride to the space station as the subjects of the Genes in Space-7 experiment, created by a team of high school students. These flies, more formally known as the Drosophila melanogaster, are a model organism, meaning that they are common subjects of scientific study. Understanding changes in the genetic material that influences circadian rhythm in microgravity can shed light on processes relevant to an astronaut’s brain function.
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For updates on other platforms, follow @ISS_Research, Space Station Research and Technology News, or our Facebook to keep up with the science happening aboard your orbiting laboratory, and step outside to see the space station passing over your town using Spot the Station.
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