Astronomy

What's happening to the big black hole in the center of our galaxy?

The Maya created a complex calendar system to regulate their world — one of the most accurate of pre-modern times.

The Vera C. Rubin Observatory, formerly the Large Synoptic Survey Telescope (LSST), was formally proposed in 2001 to create an astronomical facility that could conduct deep-sky surveys using the latest technology. This includes a wide-field reflecting telescope with an 8.4-meter (~27.5-foot) primary mirror that relies on a novel three-mirror design (the Simonyi Survey Telescope) and a 3.2-megapixel Charge-Coupled Device (CCD) imaging camera (the LSST Camera). Once complete, Rubin will perform a 10-year survey of the southern sky known as the Legacy Survey of Space and Time (LSST).

While construction on the observatory itself did not begin until 2015, work began on the telescope’s digital cameras and primary mirror much sooner (in 2004 and 2007, respectively). After two decades of work, scientists and engineers at the Department of Energy’s (DOE) SLAC National Accelerator Laboratory and their collaborators announced the completion of the LSST Camera – the largest digital camera ever constructed. Once mounted on the Simonyi Survey Telescope, this camera will help researchers observe our Universe in unprecedented detail.

The Vera C. Rubin Observatory is jointly funded by the U.S. National Science Foundation (NSF) and the U.S. Department of Energy (DOE) and is cooperatively operated by NSF NOIRLab and SLAC. When Rubin begins its ten-year survey (scheduled for August 2025), it will help address some of the most pressing and enduring questions in astronomy and cosmology. These include understanding the nature of Dark Matter and Dark Energy, creating an inventory of the Solar System, mapping the Milky Way, and exploring the transient optical sky (i.e., objects that vary in location and brightness).

A schematic of the LSST Camera. Note the size comparison; the camera will be the size of a small SUV. Credit: Vera Rubin Observatory/DOE

The LSST Camera will assist these efforts by gathering an estimated 5,000 terabytes of new raw images and data annually. “With the completion of the unique LSST Camera at SLAC and its imminent integration with the rest of Rubin Observatory systems in Chile, we will soon start producing the greatest movie of all time and the most informative map of the night sky ever assembled,” said Željko Ivezic, an astronomy professor at the University of Washington and the Director of Rubin Observatory Construction in a NoirLab press release.

Measuring 1.65 x 3 meters (5.5 x 9.8 ft), with a front lens over 1.5 m (5 ft) across, the camera is about the size of a small SUV and weighs almost 2800 kg (6200 lbs). Its large-aperture, wide-field optical imaging capabilities can capture light from the near-ultraviolet (near-UV) to the near-infrared (NIR), or 0.3 – 1 micrometers (?m). But the camera’s greatest attribute is its ability to capture unprecedented detail over an unprecedented field of view. This will allow the Rubin Observatory to map the positions and measure the brightness of billions of stars, galaxies, and transient objects, creating a robust catalog that will fuel research for years.

Said Kathy Turner, the program manager for the DOE’s Cosmic Frontier Program, these images will help astronomers unlock the secrets of the Universe:

“And those secrets are increasingly important to reveal. More than ever before, expanding our understanding of fundamental physics requires looking farther out into the Universe. With the LSST Camera at its core, Rubin Observatory will delve deeper than ever before into the cosmos and help answer some of the hardest, most important questions in physics today.”

In particular, astronomers are looking forward to using the LSST Camera to search for signs of weak gravitational lensing. This phenomenon occurs when massive galaxies alter the curvature of spacetime around them, causing light from more distant background galaxies to become redirected and amplified. This technique allows astronomers to study the distribution of mass in the Universe and how this has changed over time. This is vital to determining the presence and influence of Dark Matter, the mysterious and invisible matter that makes up 85% of the total mass in the Universe.

Similarly, scientists also want to study the distribution of galaxies and how those have changed over time, enabling them to identify Dark Matter clusters and supernovae, which may help improve our understanding of Dark Matter and Dark Energy alike. Within our Solar System, astronomers will use the LSST Camera to create a more thorough consensus of small objects, including asteroids, planetoids, and Near-Earth Objects (NEO) that could pose a collision risk someday. It will also catalog the dozen or so interstellar objects (ISOs) that enter our Solar System every year.

This is an especially exciting prospect for scientists who hope to conduct rendezvous missions in the near future that will allow us to study them up close. Now that the LSST Camera is complete and has finished being tested at SLAC, it will be shipped to Cerro Pachón in Chile (where the Vera C. Rubin Observatory is being constructed) and integrated with the Simonyi Survey Telescope later this year. Said Bob Blum, Director for Operations for Vera C. Rubin Observatory:

“Rubin Observatory Operations is very excited to see this major milestone about to be completed by the construction team. Combined with the progress of coating the primary mirror, this brings us confidently and much closer to starting the Legacy Survey of Space and Time. It is happening.”

The LSST Camera was made possible thanks to the expertise and technology contributed by international partners. These include the Brookhaven National Laboratory, which built the camera’s digital sensor array; the Lawrence Livermore National Laboratory and its industrial partners, who designed and built the lenses; the National Institute of Nuclear and Particle Physics in France, which built the camera’s filter exchange system and contributed to the sensor and electronics design.

Further Reading: NoirLab

The post The World's Largest Digital Camera is Complete. It Will Go Into the Vera Rubin Observatory appeared first on Universe Today.

The eclipse is about to begin. Totality will arrive at Mexico’s west coast around 11.07am local time, moving east until it leaves Newfoundland, Canada, around 5.16pm there

We built an app for the 2024 solar eclipse and here's why it's a labor of love.

SpaceX is set to launch 11 satellites on the Bandwagon-1 rideshare mission tonight (April 7) from NASA's Kennedy Space Center in Florida.

An account of the 2017 "Great American Eclipse" as viewed from Oregon — with my dogs.

The White House has tasked NASA with creating a new time zone for the moon by the end of 2026, as part of the United States' broader goal to establish international norms in space.

Season Two of MGM+'s sci-fi mystery show is back with new characters and more cosmic conflict on April 7.

In the buildup to the April 8 total solar eclipse, researchers set about discovering how often cities experience eclipses and where, if anywhere, on Earth witnesses the most of these events.

The biggest natural astronomical event of 2024, April 8's total solar eclipse, is almost here. Here is how the event will path out on the path of totality it sweeps across.

Here’s how to pick a viewing spot, stay on top of the weather and pack the right gear to see the total solar eclipse on April 8

In late 2021 there was a total solar eclipse visible only at the end of the Earth.

When light strikes the atmosphere all sorts of interesting things can happen. Water vapor can split sunlight into a rainbow arc of colors, corpuscular rays can stream through gaps in clouds like the light from heaven, and halos and sundogs can appear due to sunlight reflecting off ice crystals. And then there is the glory effect, which can create a colorful almost saint-like halo around objects.

Like rainbows, glories are seen when facing away from the light source. They are often confused with circular rainbows because of their similarity, but glories are a unique effect. Rainbows are caused by the refraction of light through water droplets, while glories are caused by the wave interference of light. Because of this, a glory is most apparent when the water droplets of a cloud or fog are small and uniform in size. The appearance of a glory gives us information about the atmosphere. We have assumed that some distant exoplanets would experience glories similar to Earth, but now astronomers have found the first evidence of them.

A solar glory seen from an airplane. Credit: Brocken Inaglory

The observations come from the Characterising ExOplanet Satellite (Cheops) as well as observations from other observatories of an exoplanet known as WASP-76b. It’s not the kind of exoplanet where you’d expect a glory to appear. WASP-76b is not a temperate Earth-like world with a humid atmosphere, but a hellish hot Jupiter with a surface temperature of about 2,500 Kelvin. Because of this, the team wasn’t looking for extraterrestrial glories but rather studying the odd asymmetry of the planet’s atmosphere.

WASP-76b orbits its star at a tenth of the distance of Mercury from the Sun. At such a close distance the world is likely tidally locked, with one side forever boiling under its sun’s heat and the other side always in shadow. No such planet exists in our solar system, so astronomers are eager to study how this would affect the atmosphere of such a world. Previous studies have shown that the atmosphere is not symmetrical. The star-facing side is puffed up by the immense heat, while the atmosphere of the dark side is more dense.

For three years the team observed WASP-76b as it passed in front of and behind its star, capturing data on the intersection between the light and dark side. They found that on the planet’s eastern terminator (the boundary between light and dark sides) there was a surprising increase in light. This extra glow could be caused by a glory effect. It will take more observations to confirm this effect but if verified it will be the first glory observed beyond our solar system. Currently, glories have only been observed on Earth and Venus.

The presence of a glory on WASP-76b would mean that spherical droplets must have been present in the atmosphere for at least three years. This means either they are stable within the atmosphere, or they are constantly replenished. One possibility is that the glory is caused by iron droplets that rain from the sky on the cooler side of the planet. Even if this particular effect is not confirmed, the ability of modern telescopes to capture this data suggests that we will soon be able to study many subtle effects of exoplanet atmospheres.

Reference: Demangeon, O. D. S., et al. “Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b.” Astronomy & Astrophysics 684 (2024): A27.

The post The First Atmospheric Rainbow on an Exoplanet? appeared first on Universe Today.

Astronomers routinely provide the ages of the stars they study. But the methods of measuring ages aren’t 100% accurate. Measuring the ages of distant stars is a difficult task.

The Nancy Grace Roman Space Telescope should make some progress.

Stars like our Sun settle into their main sequence lives of fusion and change very little for billions of years. It’s like watching middle-aged adults go about their business during their working lives. They get up, drive to work, sit at a desk, then drive home.

But what can change over time is their rotation rate. The Sun now rotates about once a month. When it was first formed, it rotated more rapidly.

But over time, the Sun’s rotation rate, and the rotation rate of stars the same mass or lower than the Sun’s, will slow down. The slowdown is caused by interactions between the star’s magnetic fields and the stellar wind, the stream of high-energy protons and electrons emitted by stars. Over time, these interactions reduce a star’s angular momentum, and its rotation slows. The phenomenon is called “magnetic braking,” and it depends on the strength of a star’s magnetic fields.

When the Sun rotates, the magnetic field lines rotate with it. The combination is almost like a solid object. Ionized material from the solar wind will be carried along the field lines and, at some point, will escape the magnetic field lines altogether. That reduces the Sun’s angular momentum. Image Credit: By Coronal_Hole_Magnetic_Field_Lines.svg: Sebman81Sun_in_X-Ray.png: NASA Goddard Laboratory for AtmospheresCelestia_sun.jpg: NikoLangderivative work: Aza (talk) – Coronal_Hole_Magnetic_Field_Lines.svgSun_in_X-Ray.pngCelestia_sun.jpg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=8258519

The more rapidly a star initially spins, the stronger its magnetic fields. That means they slow down faster. After about one billion years of life, stars of the same age and mass will spin at the same rate. Once astronomers know a star’s mass and rotation rate, they can estimate its age. Knowing stars’ ages is critical in research. It makes everything astronomers do more accurate, including piecing together the Milky Way’s history.

The problem is that measuring rotation rates is challenging. One method is to observe spots on stars’ surfaces and watch as they come into and out of view. All stars have star spots, though their characteristics vary quite a bit. In fact, stars can have dozens of spots, and the spots change locations. Therein lies the difficulty. It’s extremely difficult to figure out the periodicity when dozens of spots change locations on the star’s surface.

This is where the Nancy Grace Roman Space Telescope (the Roman) comes in. It’s scheduled for launch in May 2027 to begin its five-year mission. It’s a wide-field infrared survey telescope with multiple science objectives. One of its main programs is the Galactic Bulge Time Domain Survey. That effort will gather detailed information on hundreds of millions of stars in the Milky Way’s galactic bulge.

This is a simulated image of what the Roman Space Telescope will see when it surveys the Milky Way’s galactic bulge. The telescope will observe hundreds of millions of stars in the region. Image Credit: Matthew Penny (Louisiana State University)

The Roman will generate an enormous amount of data. Much of it will be measurements of how the brightness of hundreds of thousands of stars changes. But untangling those measurements and figuring out what those changes in brightness mean for stellar rotation requires help from AI.

Astronomers at the University of Florida are developing AI to extract stellar rotation periods from all that data.

Zachary Claytor is a postdoc at the University of Florida and the AI project’s science principal investigator. Their AI is called a convolutional neural network. This type of AI is well-suited to analyzing images and is used in image classification and medical image analysis, among other things.

AI needs to be trained before it can do its job. In this case, Claytor and his associates wrote a computer program to generate simulated stellar light curves for the AI to process and learn from.

“This program lets the user set a number of variables, like the star’s rotation rate, the number of spots, and spot lifetimes. Then it will calculate how spots emerge, evolve, and decay as the star rotates and convert that spot evolution to a light curve – what we would measure from a distance,” explained Claytor.

Claytor and his co-researchers have already tested their AI on data from NASA’s TESS, the Transiting Exoplanet Survey Satellite. The longer a star’s rotation period is, the more difficult it is to measure. But the team’s AI demonstrated that it could successfully determine these periods in TESS data.

The Roman’s Galactic Bulge Time Domain Survey is still being designed. So astronomers can use this AI-based effort to help design the survey.

“We can test which things matter and what we can pull out of the Roman data depending on different survey strategies. So when we actually get the data, we’ll already have a plan,” said Jamie Tayar, assistant professor of astronomy at the University of Florida and the program’s principal investigator.

“We have a lot of the tools already, and we think they can be adapted to Roman,” she added.

Artist’s impression of the Nancy Grace Roman Space Telescope, named after NASA’s first Chief of Astronomy. When launched later this decade, the telescope will measure the rotational periods of hundreds of thousands of stars and, with the help of AI, will determine their ages. Credits: NASA

Measuring stellar ages is difficult, yet age is a key factor in understanding any star. Astronomers use various methods to measure ages, including evolutionary models, a star’s membership in a cluster of similarly-aged stars, and even the presence of a protoplanetary disk. But no single method can measure every star’s age, and each method has its own drawbacks.

If the Roman can break through this barrier and accurately measure stellar rotation rates, astronomers should have a leg-up in understanding stellar ages. But there’s still one problem: magnetic braking.

This method relies on a solid understanding of how magnetic braking works over time. But astronomers may not understand it as thoroughly as they’d like. For instance, research from 2016 showed that magnetic braking might not slow down older stars as much as thought. That research found unexpectedly rapid rotation rates in stars more evolved than our Sun.

Somehow, astronomers will figure this all out. The Roman Space Telescope should help, as its vast trove of data is bound to lead to some unexpected conclusions. One way or another, with the help of the Roman Space Telescope, the ESA’s Gaia mission, and others, astronomers will untangle the problem of measuring everything about stars, including their ages.

The post Roman Will Learn the Ages of Hundreds of Thousands of Stars appeared first on Universe Today.

Books are becoming a key part of disaster recovery, helping toddlers—and their parents—cope with increasing hurricanes, earthquakes and wildfires

From building an eclipse viewer to using the sun to pop balloons, here's a child-friendly activity guide for April's eclipse

Earthquakes in the Northeast are usually too small to feel, but larger temblors like the 4.8 magnitude quake in New Jersey aren’t unheard of