cerro tololo inter american observatory

Cerro Tololo Trails : Early one moonlit evening car lights left a wandering trail along the road to the Chilean Cerro Tololo Inter-American Observatory. Setting stars left the wandering trails in the sky. The serene view toward the mountainous horizon was captured in a telephoto timelapse image and video taken from nearby Cerro Pachon, home to Gemini South. Afforded by the mountaintop vantage point, the clear, long sight-line passes through layers of atmosphere. The changing atmospheric refraction shifts and distorts the otherwise steady apparent paths of the stars as they set. That effect also causes the distorted appearance of Sun and Moon as they rise or set near a distant horizon. via NASA

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Superluminous supernova marks the death of a star at cosmic high noon

The death of a massive star in a distant galaxy 10 billion years ago created a rare superluminous supernova that astronomers say is one of the most distant ever discovered. The brilliant explosion, more than three times as bright as the 100 billion stars of our Milky Way galaxy combined, occurred about 3.5 billion years after the big bang at a period known as “cosmic high noon,” when the rate of star formation in the universe reached its peak.

Superluminous supernovae are 10 to 100 times brighter than a typical supernova resulting from the collapse of a massive star. But astronomers still don’t know exactly what kinds of stars give rise to their extreme luminosity or what physical processes are involved.

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HOUSE-SIZED NEAR-EARTH OBJECTS RARER THAN WE THOUGHT

In 2013 a small meteoroid, the size of a house, hurtled through Earth’s atmosphere and exploded over the Russian city of Chelyabinsk. The explosion shattered windows, and more than a thousand people were treated for injuries from flying debris. How many similar-sized rocks have orbits that bring them close to Earth? A new study has answered that question using the Dark Energy Camera (DECam) on the Blanco telescope at the Cerro Tololo Inter-American Observatory. The result lends new insights into the nature and origin of small meteoroids.

Near-Earth objects (NEOs) are asteroids or comets whose orbits bring them close to Earth’s orbit. Their close approach makes them a potential Earth-impact hazard capable of causing widespread destruction.

While very large (10-kilometer-sized) impactors can induce mass extinction events like the event that led to the demise of the dinosaurs, much smaller impactors can also wreak havoc. The meteoroid that exploded in Chelyabinsk unleashed a powerful shock wave that destroyed buildings and blew people off their feet. Relatively petite at a ‘mere’ 17 meters in diameter, comparable to the size of a 6-story building, the impactor, when it exploded, released about 10 times the energy of the Hiroshima atomic bomb.

A survey for NEOs being carried out with DECam on the 4-m Blanco telescope at the Cerro Tololo Inter-American Observatory has now estimated the number of objects in near-Earth orbit that are similar in size to the Chelyabinsk impactor. Lori Allen, Director of the Kitt Peak National Observatory and the lead investigator on the study, explained, “There are around 3.5 million NEOs larger than 10 meters, a population 10 times smaller than inferred in previous studies. About 90% of these NEOs are in the Chelyabinsk size range of 10-20 meters.”

The study, to be published in the Astronomical Journal, is the first to derive, from a single observational data set with no external model assumptions, the size distribution of NEOs from 1 kilometer down to 10 meters. A similar result was obtained in an independent study that analyzed multiple data sets (Tricarico 2017).

While the surprising results do not alter the impact threat from house-sized NEOs, which is constrained by the observed rate of Chelyabinsk-like bolide events, they do lend new insights into the nature and origin of small NEOs.

David Trilling (Northern Arizona University), the first author of the study, explained how the study reconciled the surprisingly small number of house-sized NEOs with the observed rate of Chelyabinsk-like events: “If house-sized NEOs are responsible for Chelyabinsk-like events, our results seem to say that the average impact probability of a house-sized NEO is actually 10 times greater than the average impact probability of a large NEO. That sounds strange, but it may be telling us something interesting about the dynamical history of NEOs.”

Trilling speculates that the orbital distributions of large and small NEOs differ, with small NEOs concentrated in bands of collisional debris that are more likely to impact the Earth. Bands of debris could be produced when larger NEOs fragment into swarms of smaller boulders. Testing this hypothesis is an interesting problem for the future.

Estimating the study’s detection efficiency was critical to the result. Frank Valdes (NOAO), who developed the data reduction and analysis pipeline for the project, pointed out that “the best way to measure detection efficiency is by implanting synthetic NEOs into the data stream and then detecting the fake ones in the same way real NEOs are detected.”

Well-matched to the study of small, faint NEOs, the large aperture of the 4-meter Blanco telescope and the wide field-of-view of DECam were also vital to the study. Describing the broad science reach of DECam, Allen remarked, “DECam has the power to revolutionize many fields of astronomy, from our understanding of dark matter and dark energy, to the search for distant planets in our solar system and our understanding of the near-Earth environment.”

TOP IMAGE….Orbits of known Near Earth Objects.
CENTRE IMAGE….Near Earth Objects sizes
LOWER IMAGE….Near Earth Objects family groups
BOTTOM IMAGE….Near Earth Objects populations

Dawn of the cosmos: Seeing galaxies that appeared soon after the Big Bang

Arizona State University astronomers Sangeeta Malhotra and James Rhoads, working with international teams in Chile and China, have discovered 23 young galaxies, seen as they were 800 million years after the Big Bang. The results from this sample have been recently published in the Astrophysical Journal.

Long ago, about 300,000 years after the beginning of the universe (the Big Bang), the universe was dark. There were no stars or galaxies, and the universe was filled with neutral hydrogen gas. In the next half billion years or so the first galaxies and stars appeared. Their energetic radiation ionized their surroundings, illuminating and transforming the universe.

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This composite image is a view of the colorful Helix Nebula taken with the Advanced Camera for Surveys aboard NASA’s Hubble Space Telescope and the Mosaic II Camera on the 4-meter telescope at Cerro Tololo Inter-American Observatory in Chile. The object is so large that both telescopes were needed to capture a complete view. The Helix is a planetary nebula, the glowing gaseous envelope expelled by a dying, sun-like star. The Helix resembles a simple doughnut as seen from Earth. But looks can be deceiving. New evidence suggests that the Helix consists of two gaseous disks nearly perpendicular to each other.

One possible scenario for the Helix’s complex structure is that the dying star has a companion star. One disk may be perpendicular to the dying star’s spin axis, while the other may lie in the orbital plane of the two stars. The Helix, located 690 light-years away, is one of the closest planetary nebulas to Earth.

The Hubble images were taken on November 19, 2002; the Cerro Tololo images on Sept. 17-18, 2003.

Object Name: Helix Nebula

Image Type: Astronomical

Credit: NASA, ESA, C.R. O'Dell (Vanderbilt University), M. Meixner and P. McCullough (STScI)

Time And Space

NGC 3576: The Statue of Liberty Nebula : Whats happening in the Statue of Liberty nebula? Bright stars and interesting molecules are forming and being liberated. The complex nebula resides in the star forming region called RCW 57. This image showcases dense knots of dark interstellar dust, bright stars that have formed in the past few million years, fields of glowing hydrogen gas ionized by these stars, and great loops of gas expelled by dying stars. A detailed study of NGC 3576, also known as NGC 3582 and NGC 3584, uncovered at least 33 massive stars in the end stages of formation, and the clear presence of the complex carbon molecules known as polycyclic aromatic hydrocarbons . PAHs are thought to be created in the cooling gas of star forming regions, and their development in the Suns formation nebula five billion years ago may have been an important step in the development of life on Earth. The featured image was taken at the Cerro Tololo Inter-American Observatory in Chile. via NASA

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SYMMETRY MAGAZINE
Art of Darkness
By Rashmi Shivni

The Dark Energy Survey’s art show offers a glimpse of the expanding universe.
Imagine a clear night in the mountains, away from glaring city lights. In the sky, gleaming speckles from distant stars cascade into the bright streams of the Milky Way. Almost everything in sight is part of our home galaxy.
To provide a glimpse beyond our galaxy and into an ever-expanding universe, the Department of Energy’s Fermilab is hosting the Art of Darkness, an exhibition by Dark Energy Survey collaborators. The exhibit opened Feb. 19 in the Fermilab Art Gallery and showcases images from celestial objects from DES’ Dark Energy Camera, DECam.
“We see so much information in the artwork that ends up being a small part of the whole DES footprint,” says Brian Nord, an astrophysicist and contributor to the DES art exhibit. “This showcase highlights the depth of a universe we don’t completely see with the naked eye.”
DES is a five-year survey that covers one-eighth of the sky to better describe dark energy–the force driving the universe’s accelerated expansion. The collaboration has more than 400 scientists from around 30 institutions. It uses the 570-megapixel DECam, one of the largest digital cameras in the world, perched atop the Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile.
The select few galaxies in the exhibit are from a narrow swath of the sky survey. Creating these photographs for the gallery requires an image-processing pipeline, a method of “cleaning up” the images by removing artifacts such as satellites, airplane or cosmic ray trails, or defects from the camera hardware, says Nikolay Kuropatkin, a DES computational physics software developer.
“We use this pipeline for our scientific surveys, but it turns out to be a good tool for artwork as well,” says Kuropatkin.

DECam is a monochromatic camera. Part of the exhibit process required Marty Murphy, an operations specialist in Fermilab’s Accelerator Division, and Nord to add color and further edit the images with an artistic eye.
Five different filters are individually placed between the telescope and camera to gather color information about the galaxy in view. Each filter corresponds to a different bandwidth, or a range of frequencies, on the electromagnetic spectrum. Those single-filter images are then combined to produce a full-color photo.
“A lot of the information in the initial pictures is lost because lots of light emits from the invisible ends of the electromagnetic spectrum,” Murphy says. “We try to bring out colors from the visible spectrum that somewhat represent what’s there and fix any discrepancies between reality and the artwork.”
This close-to-reality representation also helps scientists understand the properties of the galaxies in view. For instance, small clusters that appear red or warmer in color tell us that they are further away from us due to the expansion of the universe, says Brian Yanny, a DES data management project scientist.
“From that we can figure out how big space is and how dark energy might be affecting the size of the universe from the redshift of the object,” he says.
But the art gallery is made of more than just galaxy images. There’s a 3D print of the cosmic web derived from a computer simulation. There’s also a colorful dark matter map of the actual cosmic web that DES observes made using gravitational lensing, a distortion seen when light from background galaxies bends from a massive foreground object.
“Once you know the explanations behind the workings of the cosmos, you realize there are forces out there that make the universe beautiful,” Yanny says. “We’ve come to understand that dark matter holds the shape of spiral galaxies, which have a rapid and unstable spin. Without dark matter, we would not experience the cosmos the way we do now.”
Alongside the DECam photos are images and time-lapse videos from the Blanco Telescope and the surrounding landscapes that provide another perspective of how the very act of research helps bring out the beauty of the universe. The images (on display at Fermilab through April) come from 11 DES collaborators and were collected over the first three seasons of observations, which ended in February. DES will take data for two more years, from August to February.
“I hope the images from the camera combined with the pictures from the site can somehow merge two perspectives,” Nord says. “In essence, it’s humans looking out to the cosmos and the universe looking back at us.”

This image of 30 Doradus, the Tarantula Nebula, in the Large Magellanic Cloud (LMC) was taken with the Curtis Schmidt telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile, as part of the Magellanic Cloud Emission Line Survey (MCELS) project. The Tarantula Nebula is a giant star-forming region, where energy from hot, young stars in the region creates dramatic voids and filaments in the surrounding gas. Located 160,000 light-years distant in the southern constellation Dorado, the LMC is considered the closest large galaxy to Earth.  Because of the proximity and low foreground absorption of the LMC, it is an ideal laboratory both for studies of individual HII regions, supernova remnants, and superbubbles, and for investigations of global properties using samples of these objects. MCELS is designed to provide uniform datasets in optical emission lines that are necessary to conduct this research. The MCELS observations toward the 30 Doradus region have been used to investigate the physical properties of the HII region, examine the physical conditions of supernova remnants in the field, and study the large-scale structure of the ionized gas.  This color image was produced using three separate exposures taken in hydrogen (red), sulfur (green), and oxygen (blue) filters. Caption: NOAO. Please read Conditions of Use before downloading. S. POINTS, C. SMITH, R. LEITON, C. AGUILERA AND NOAO/AURA/NSF

Globule Goes Chomp

The flower-like image of this star-forming region in Earth’s southern skies was imaged using a 64-megapixel Mosaic imaging camera on the National Science Foundation’s Victor M. Blanco telescope at Cerro Tololo Inter-American Observatory.

Cometary globules are isolated, relatively small clouds of gas and dust within the Milky Way. This example, called CG4, is about 1,300 light years from Earth. Its head is some 1.5 light-years in diameter, and its tail is about eight light-years long. The dusty cloud contains enough material to make several Sun-sized stars. CG4 is located in the constellation of Puppis.

The head of the nebula is opaque, but glows because it is illuminated by light from nearby hot stars. Their energy is gradually destroying the dusty head of the globule, sweeping away the tiny particles which scatter the starlight. This particular globule shows a faint red glow from electrically charged hydrogen, and it seems about to devour an edge-on spiral galaxy (ESO 257-19) in the upper left. In reality, this galaxy is more than a hundred million light-years further away, far beyond CG4. The image from the Blanco 4-meter telescope was taken in four filters, three of which are for blue, green and near-infrared light. The fourth is designed to isolate a specific color of red, known as hydrogen-alpha, which is produced by warm hydrogen gas.

Image Credit: T.A. Rector/University of Alaska Anchorage, T. Abbott and NOAO/AURA/NSF

What’s the closest active galaxy to planet Earth? That would be Centaurus A, only 11 million light-years distant. Spanning over 60,000 light-years, the peculiar elliptical galaxy is also known as NGC 5128. Forged in a collision of two otherwise normal galaxies, Centaurus A’s fantastic jumble of young blue star clusters, pinkish star forming regions, and imposing dark dust lanes are seen here in remarkable detail. The colorful galaxy portrait was recorded under clear Chilean skies at the Cerro Tololo Inter-American Observatory. Near the galaxy’s center, left over cosmic debris is steadily being consumed by a central black hole with a billion times the mass of the Sun. As in other active galaxies, that process likely generates the radio, X-ray, and gamma-ray energy radiated by Centaurus A.

Image Credit & Copyright: SSRO-South (Steve Mazlin, Jack Harvey, Daniel Verschatse, Rick Gilbert) and Kevin Ivarsen (PROMPT / CTIO / UNC)

A new Einstein Ring: Distant galaxy lensed by gravity

A multinational team of astronomers has found an Einstein Ring, a rare image of a distant galaxy lensed by gravity. The scientists, from Spain, Italy and the USA, report their discovery in Monthly Notices of the Royal Astronomical Society.

In his seminal general theory of relativity published a century ago, Albert Einstein predicted that gravity would distort the fabric of spacetime, and that light would follow curved paths as a result. Astronomers first observed this effect in 1919, by measuring the position of stars near the Sun during the 1919 total solar eclipse, and noting a slight shift resulting from the gravitational field of our nearest star. On a larger scale, light from distant galaxies is bent by black holes and massive galaxies that lie between them and Earth. The intervening objects act as lenses, creating arcs and ‘Einstein rings’ of light.

These rings are still comparatively rare and usually appear as small features in the sky. This makes them hard to see clearly, and most are observed with radio telescopes, or with the Hubble Space Telescope. Their rarity derives from the huge distances involved, and the low probability of our Galaxy, the lens galaxy and the distant galaxy all being almost exactly in line.

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