By using supercomputers to simulate the birth and evolution of individual stars and star clusters in the Milky Way
Space news (astrophysics: studying star formation; 3-D computer simulations) – NASA Advanced Supercomputing laboratory located at NASA’s Ames Research Center –
How do astronomers study the formation of stars? Astronomers use complex computer code, run on one of the fastest, most powerful supercomputers on Earth to simulate the processes involved in the formation of individual stars and star clusters in the Milky Way. Using simulations capturing a mix of gas, dust, magnetic fields, gravity and other physical phenomena, astrophysicists study the birth and evolution of young, nearby stars and star clusters.
The image above was created using state-of-the-art Orion2 computer code written by geniuses at the University of California, Berkeley, and Lawrence Livermore National Laboratory and simulated on the powerful, ultra-fast Pleiades supercomputer located at NASA Advanced Supercomputing complex. Considered the seventh most powerful supercomputer in the US, it was necessary to achieve results closely matching data obtained through observations made with the Hubble Space Telescope.
“Our simulations, run on Pleiades and brought to life by the visualization team at the NAS facility at Ames, were critical to obtaining important new results that match with Hubble’s high-resolution images and other observations made by a variety of space and Earth-based telescopes,” said Richard Klein, adjunct professor at UC Berkeley and astrophysicist at LLNL. “A key result, supported by observation, is that some star clusters form like pearls in a chain along elongated, dense filaments inside molecular clouds—so-called “stellar nurseries.”
The video simulation here shows the evolution of a massive cloud of gas and dust over a period of 700,000 years. Astrophysicists used the computing power of the Pleiades supercomputer, operating using the Orion2 code to create this amazing cosmic tapestry. The gravitational collapse of the cloud results in the birth of a stellar object called an infrared dark cloud (IRDC) filament. Protostars begin to form within the cloud, highlighted by bright orange regions strewn across the body of the central and bordering filaments.
“Without NASA’s vast computational resources, it would not have been possible for us to produce these immense and complex simulations that include all the output variables we need to get these new results and compare them with observations,” Klein explained. “The ORION2 simulations incorporate a complex mix of gravity, supersonic turbulence, hydrodynamics (motion of molecular gas), radiation, magnetic fields, and highly energetic gas outflows. The science team conducted many independent tests of each piece of physics in ORION against known data to demonstrate the code’s accuracy.”
The team’s back at work trying to devise even better simulations of star formation by improving the resolution and zooming into the action. “Higher resolution in the simulations will enable us to study the details of the formation of stellar disks formed around protostars. These disks allow mass to transfer onto the protostars as they evolve, and are thought to be the structures within which planets eventually form,” said Klein.
More work to do
They’ll need additional time on Pleiades and lots of extra storage during the next few years to tweak their simulations. The team seems to be on the trail of a real breakthrough in understanding and knowledge concerning the processes leading to star formation in the Milky Way. They appear to have their collective eye on the bigger picture. “Understanding star formation is a grand challenge problem. Ultimately, our results support NASA’s science goal of determining the origin of stars and planets, as part of its larger challenge of figuring out the origin of the entire universe.”
You can learn more about the formation of stars here.
Two stars shine brightly through aring of swirling dust and gas
Space news (November 04, 2015) – approximately 160 parsecs from Earth in the Chamaeleon I Dark Cloud –
Astronomers using the Hubble Space Telescope recently viewed one of the youngest and closest star systems found during the human journey to the beginning of space and time. Star system Dl Cha is a young quadruple system of suns deep within the Chamaeleon Complex, a mysterious region of space comprised of three clouds of gas and dust.Composed of two binary star systems, Dl Cha is one of the best young systems to study to learn more about star formation because of its youth and nearness to Sol.
Dl Cha is located in Chamaeleon I Dark Cloud, one of the closest star-forming regions to Earth, with as many as 200-300 young suns. Newly-formed suns that mold the dust and gas in the surrounding region into a spiraling wrap enveloping Dl Cha in a light-absorbing shroud. A shroud of gas and dust scientists are peering through using the latest ground and space telescopes to learn more aboutthe processes the cosmos uses to create new stars.
The Chamaeleon I Dark Cloud contains 70-90 mysterious X-ray sources, including Cha Halpha, the first X-ray emitting brown dwarf ever located. As the gas and dust swirls and moves in this region of space, more young stars will be viewed, and the veil surrounding the mystery of these X-ray sources and star formation lifted. A veil lifting astronomers expect to reveal more cosmic mysteries as the human journey to the beginning of space and time unfolds.
You can learn more about star formation in the cosmos here.
Space news (March 10, 2015) – around 2,000 light-years away in dark cloud LDN 981 –
This NASA/ESA Hubble Space Telescope image shows dust surrounding T Tauri star V1331 Cyg spiraling outward driven by a jet emanating from the young star astronomers think.
This image is unique because it gives us a view of a main sequence star similar to our own sun in the process of being formed and of one of the poles of the young star. Astronomers think we’re looking down the path of a jet emanating from a pole of the young star that cleared star dust from the path giving us this inspiring view.
Called a reflection nebula, the dusty shape here resembles a snail or beating wing, and is part of the process of the birth of a young star and possible solar system astronomers believe. Astronomers are currently looking at the data and images for features suggesting the formation of a low-mass object in the outer circumstellar disk.
Read about something interesting astronomers discovered about red dwarf stars
Understanding how large star clusters form could tell us more about star formation when the universe was young
Astronomers news (2013-10-14) – Tonight we’ll journey to the truly titanic 30 Doradus nebula (also called the Tarantula nebula), 170 light-years away in the Large Magellanic Cloud, aboard the Hubble Space Telescope. The Large Magellanic Cloud is a smaller satellite galaxy to the Milky Way, where astronomers recently discovered something they suspected about the formation of larger star clusters.
Using Hubble’s Wide Field Camera 3, we’ll be able to look at images of the Tarantula nebula filled with startling reds, greens and blues, which indicates to astronomers the elemental composition of the stars in the region. Blue light is from the hottest, most massive stars astronomers have found to date. Red light is from fluorescing hydrogen gas, while green light is the glow of oxygen.
Every element on the periodic table gives off light with a specific signature upon fluorescing. Scientists use this knowledge to analyze the light reaching Hubble’s Wide Field Camera 3 from the Tarantula nebula to determine the elemental composition of the stars in the region .They hope to use this knowledge to answer questions they have concerning star formation when the universe was still in its infancy.
NASA astronomers see something different going on in 30 Doradus
We’ll specifically journey to a region of the 30 Doradus nebula where astronomers recently discovered a pair of star clusters which they first thought was a single star cluster, is in fact a pair of star clusters in the initial stages of merging into a larger star cluster. Astronomers now think the merging of star clusters could help explain the abundance of large star clusters throughout the visible universe.
Lead scientist Elena Sabbi of the Space Telescope Science Institute in Baltimore, Maryland and her team first started looking at the region to find runaway stars. Runaway stars are fast-moving stars that have been kicked out of the stellar nursery where they first formed. Astronomers found the region surrounding 30 Doradus has a large number of runaway stars, which according to current star formation theories could not have formed at their present location. Astronomers now believe the runaway stars outside 30 Doradus could have been ejected out of the region at high speed due to dynamic interactions with other stellar bodies as the two star clusters merge into one larger star cluster.
Astrophysicists and astronomers started looking for clues
The first clue to the true nature of the event astronomers were viewing was the fact that parts of the star cluster varied in age by about 1 million years. Upon further study the team noticed the distribution of low-mass stars detected by Hubble were not spherical in shape as astronomers expected, but resembled the elongated shape of two merging galaxies. Now astronomers are studying this region of space and time to find clues to help them understand the way larger star clusters are formed in the universe. They also hope this discovery will help determine interesting and enlightening facts concerning the formation of star clusters when the universe was still young.
Astronomers are also looking further at this region of space and time to find other star clusters in the process of merging in the 30 Doradus nebula. They plan on using the ability of the James Webb Space Telescope to detect infrared light , once it comes on line, to take a closer look at areas within the Tarantula nebula where they think stars hidden within cocoons of dust are blocked from the view of telescopes and instruments detecting visible light.
Stars begin life as clouds of cold gas and dust that transform into blazing hot fireballs
Star dust, star dust, burning bright
Amid the glare of ancient light
Eternity stares back from the past
Reborn we’ll be one day at last
NASA astronomy: stellar astrophysics
Astronomy questions and answers – September 19, 2013 – Walk out to a dark viewing spot anywhere on the Earth on a clear night and look up at the night sky. Your eyes will take in ancient light from stars in the Milky Way that covers the whole sky above you. Deep within the stellar nurseries of the Milky Way new stars are being formed using processes NASA astronomers are currently studying in an attempt to understand how stars are born. Star forming processes responsible for the formation of the stars you see in the night sky. Processes they can see at work in the stellar nurseries of the Milky Way, like the Orion Nebula (M42) and Cygnus X.
Journey with me to stellar nurseries deep within the dark regions of the Milky Way, the dark patches you can see in the night sky above. The birthing grounds of young stars in the Milky Way, these dark patches in the night sky are in fact clouds of interstellar gas that appear dark because they block the starlight from distant stars. Astronomers believe deep within the birthing grounds of the Milky Way, new stars are being formed at the rate of about 2 or 3 new stars each year.
Star formation theories
Present theories on star formation put forth by NASA astronomers show star formation is a complicated process affected by nearby massive stars, other star forming regions, and even the spiral structure of the Milky Way. These theories only become more complicated when astronomers look at the formation of groups of stars.
In order to try to simulate star formation, some astronomers use sophisticated computer models, while others incorporate observations in different wavelengths and use them to create three-dimensional images of the sky. Working together these two different groups of astronomers are trying to determine exactly how stars are born.
NASA astronomers working on present theories of star formation think the Milky Way is filled with clouds of gas and dust they call the interstellar medium. They also think slight over densities within these clouds of gas and dust could trigger star formation, over densities that could be produced by the turbulent forces present in these clouds of gas and dust. Astronomers studying slight over densities within star forming clouds of gas and dust believe these slightly denser regions could eventually become main sequence stars within a few million years.
Some NASA astronomers believe the intense radiation from groups of hot, bright stars located close to one another could create the necessary turbulence in the interstellar medium to trigger star formation. Other astronomers believe nearby galaxies and even large clouds of gas and dust could cause turbulence in the interstellar medium which could also be part of the star forming process. Many astronomers also believe the resulting shock wave after a supernova could create spiral density waves capable of compressing material and initiating star formation.
Gravity at Work
Present theories on the formation of main sequence stars being proposed by NASA astronomers involves the force of gravity. Gravity pulls the gas and dust within the interstellar medium into denser regions, which results in a cloud increasing in size and contracting. The rotation velocity of the cloud increases as it contracts due to conservation of angular momentum, in the same way a figure skater’s spin speed increases as they bring their arms closer to their body.
At the same time the temperature in the core of the cloud increases as it shrinks due to the force of gravity. The charged particles within the cloud at this time can only move in specific directions in the magnetic field in the region. This results in the rotational velocity of the cloud slowing, but not stopping, otherwise astronomers think stars would never form in these dense clouds of gas and dust.
In the case of main sequence stars astronomers think regions of dense clouds of gas and dust would begin to contract to an area the size of our solar system tens of thousands of years after beginning to slow. At this time astronomers think the temperature at the centre of dense clouds of dust and gas would be in the region of 10,000 kelvins. They call the central region of such a cloud at this time a protostar.
Protostars at this time in their life cycle are often more luminous than the main sequence star they eventually become, because they have a greater surface from which to radiate energy. This brightness allows NASA astronomers to view protostars as they continue to gravitationally attract more gas and dust, shrink and heat up internally. The luminosity of a protostar begins to decrease as it’s outer surface shrinks under the force of gravity. Astronomers believe the cloud and protostar eventually spin faster and flatten out into a disk.
Astronomers using data collected by several different astronomical instruments recently presented far-infrared images of three Class 0 protostar systems in Perseus: L1448C, the triple system L1448N, and IRAS 03282+3035. Seven hundred and fifty light-years from Earth, all three of these protostars were seen powering bipolar molecular outflows, which astronomers think are in fact epic jets of water being thrust into interstellar space. Calculations by NASA astronomers indicates these jets of water are shooting out into interstellar space at speeds of around 120,000 miles per hour and at a rate equal to about 100 million times the volume of water flowing in the Amazon every second of the day.
Astronomers think these jets of water and material help to channel radiation and mass away from the protostar, which helps to clear the central region of debris and reveal the protostar. They also think it could be possible the galaxy was seeded with water through this process, which might change thoughts on the possibility of life in the galaxy. The remaining material is then accreted by the protostar, or forms part of a residual disk, which NASA astronomers think could form planets.
The core of a protostar will reach 1 million kelvin at sometime during the contraction and heating up of the cloud, at which time it will begin fusing deuterium to helium. Deuterium is the easiest nucleus to fuse, so it makes sense this would be the starting point. Once the core has contracted enough to reach a density where the core reaches 10 million degrees kelvins, hydrogen nuclei will begin fusing into helium. At this point star astronomers also think a protostar will reach an equilibrium point where the radiative energy from fusion balances gravitational pull of its mass. This new star is now a main sequence star, which has formed over millions of years.
Simulating the Birth of a Star
The process of star birth takes millions of years to complete, so how do astronomers determine the way outside factors affect the process by which new stars are born? Modern astronomers are presently using supercomputers to help simulate star formation models in the hope they can determine why the mass distribution of newly formed stars appears to be universal. They want to understand why this average mass of newly formed stars exists. They also want to know the process by which it occurs.
Present star formation models take into account the effects of thermodynamics, magnetic fields, radiative processes, and of course gravity. Star astronomers are also trying to determine other factors they need to include in models, like the way new stars affect their own star forming environments. This includes factors like young stars heating up the gas and dust surrounding them and moving gas and dust around through bipolar molecular flows.
The key question NASA astronomers want to answer at this point is whether or not present star formation models can reproduce the properties of exact parts of the star forming process. Astronomers will also want to determine the most massive star that can be formed depending on the size of a cloud of dust and gas. They’ll try to find answers by looking at the chemical composition, magnetic fields, ionization, age and other factors of large clouds of star forming dust and gas in the night sky.
Peering into Stellar Nurseries
How do NASA astronomers look into the heart of stellar nurseries in the Milky Way? Astronomers use instruments designed to detect specific wavelengths of light radiation emitted during the formation of new stars. During the beginning stages of star birth a new star emits radio waves as it contracts astronomers look for as an indicator of new star formation. At this time the core of a contracting cloud of gas and dust is too cold to emit visible and infrared radiation.
Once the cloud forms a protostar it will begin to emit light radiation, which will be blocked by the material surrounding the new star. The light radiation emitted by a protostar is absorbed by the surrounding material, which radiates infrared radiation toward Earth NASA astronomers detect using space and ground-based telescopes specifically designed for the job.
Astronomers have used the Spitzer Space Telescope to view hundreds of protostars forming in large clouds of gas and dust in the stellar nurseries of the Milky Way. In the future they’ll use instruments and telescopes designed to detect millimetre waves in the microwave range in order to get a better view of the beginning stages of star birth. To date astronomers report detecting a compact source embedded in cold gas within stellar nurseries only detectable at these wavelengths.
NASA astronomers trying to piece together the puzzle of star formation in the Milky Way are also using reconstructed images of star-forming regions from past observations. Using 2-D images, positional data, and velocities for an entire cloud, they have been able to create 3-D models researchers can then analyze. 3-D models that show unforeseen structures hidden within stellar nurseries and even regions of star formation they weren’t expecting to see.
Click this link to watch a You Tube videos on how a star is born