NASA Astronomy Picture of the Day

August 16, 2024

Meteor Borealis

A single exposure made with a camera pointed almost due north on August 12 recorded this bright Perseid meteor in the night sky west of Halifax, Nova Scotia, Canada. The meteor's incandescent trace is fleeting. It appears to cross the stars of the Big Dipper, famous northern asterism and celestial kitchen utensil, while shimmering curtains of aurora borealis, also known as the northern lights, dance in the night. Doubling the wow factor for night skywatchers near the peak of this year's Perseid meteor shower auroral activity on planet Earth was enhanced by geomagnetic storms. The intense space weather was triggered by flares from an active Sun.

https://apod.nasa.gov/apod/astropix.html?

NASA Citizen Scientists Spot Object Moving 1 Million Miles Per Hour

Aug 15, 2024

Most familiar stars peacefully orbit the center of the Milky Way.

But citizen scientists working on NASA’s Backyard Worlds: Planet 9 project have helped discover an object moving so fast that it will escape the Milky Way’s gravity and shoot into intergalactic space.

This hypervelocity object is the first such object found with the mass similar to or less than that of a small star.

Backyard Worlds uses images from NASA’s WISE, or Wide-field Infrared Explorer, mission, which mapped the sky in infrared light from 2009 to 2011.

It was re-activated as NEOWISE (Near-Earth Object Wide-field Infrared Survey Explorer) in 2013 and retired on Aug. 8, 2024.

A few years ago, longtime Backyard Worlds citizen scientists Martin Kabatnik, Thomas P. Bickle, and Dan Caselden spotted a faint, fast-moving object called CWISE J124909.08+362116.0, marching across their screens in the WISE images. Follow-up observations with several ground-based telescopes helped scientists confirm the discovery and characterize the object.

These citizen scientists are now co-authors on the team’s study about this discovery published in the Astrophysical Journal Letters (a pre-print version is available here).

“I can't describe the level of excitement,” said Kabatnik, a citizen scientist from Nuremberg, Germany.

“When I first saw how fast it was moving, I was convinced it must have been reported already.”

CWISE J1249 is zooming out of the Milky Way at about 1 million miles per hour. But it also stands out for its low mass, which makes it difficult to classify as a celestial object.

It could be a low-mass star, or if it doesn’t steadily fuse hydrogen in its core, it would be considered a brown dwarf, putting it somewhere between a gas giant planet and a star.

Ordinary brown dwarfs are not that rare. Backyard Worlds: Planet 9 volunteers have discovered more than 4,000 of them!

But none of the others are known to be on their way out of the galaxy.

This new object has yet another unique property. Data obtained with the W. M. Keck Observatory in Maunakea, Hawaii, show that it has much less iron and other metals than other stars and brown dwarfs.

This unusual composition suggests that CWISE J1249 is quite old, likely from one of the first generations of stars in our galaxy.

Why does this object move at such high speed? One hypothesis is that CWISE J1249 originally came from a binary system with a white dwarf, which exploded as a supernova when it pulled off too much material from its companion.

Another possibility is that it came from a tightly bound cluster of stars called a globular cluster, and a chance meeting with a pair of black holes sent it soaring away.

“When a star encounters a black hole binary, the complex dynamics of this three-body interaction can toss that star right out of the globular cluster,” says Kyle Kremer, incoming assistant professor in UC San Diego’s Department of Astronomy and Astrophysics.

Scientists will look more closely at the elemental composition of CWISE J1249 for clues about which of these scenarios is more likely.

This discovery has been a team effort on multiple levels—a collaboration involving volunteers, professionals, and students.

Kabatnik credits other citizen scientists with helping him search, including Melina Thévenot, who “blew my mind with her personal blog about doing searches using Astronomical Data Query Language,” he said.

Software written by citizen scientist Frank Kiwy was also instrumental in this finding, he said.

The study is led by Backyard Worlds: Planet 9 science team member Adam Burgasser, a professor at the University of California, San Diego, and includes co-authors Hunter Brooks and Austin Rothermich, astronomy students who both began their astronomy careers as citizen scientists.

https://science.nasa.gov/get-involved/citizen-science/nasa-citizen-scientists-spot-object-moving-1-million-miles-per-hour/

The Summer Triangle’s Hidden Treasures

Aug 15, 2024

August skies bring the lovely Summer Triangle asterism into prime position after nightfall for observers in the Northern Hemisphere.

Its position high in the sky may make it difficult for some to observe its member stars comfortably, since looking straight up while standing can be hard on one’s neck!

While that isn’t much of a problem for those that just want to quickly spot its brightest stars and member constellations, this difficulty can prevent folks from seeing some of the lesser known and dimmer star patterns scattered around its informal borders.

The solution? Lie down on the ground with a comfortable blanket or mat or grab a lawn or gravity chair and sit luxuriously while facing up.

You’ll quickly spot the major constellations about the Summer Triangle’s three corner stars: Lyra with bright star Vega, Cygnus with brilliant star Deneb, and Aquila with its blazing star, Altair.

As you get comfortable and your eyes adjust, you’ll soon find yourself able to spot a few constellations hidden in plain sight in the region around the Summer Triangle: Vulpecula the Fox, Sagitta the Arrow, and Delphinus the Dolphin!

You could call these the Summer Triangle’s “hidden treasures” – and they are hidden in plain sight for those that know where to look!

Vulpecula the Fox is located near the middle of the Summer Triangle, and is relatively small, like its namesake.

Despite its size, it features the largest planetary nebula in our skies: M27, aka the Dumbbell Nebula! It’s visible in binoculars as a fuzzy “star” and when seen through telescopes, its distinctive shape can be observed more readily - especially with larger telescopes.

Planetary nebulae, named such because their round fuzzy appearances were initially thought to resemble the disc of a planet by early telescopic observers, form when stars similar to our Sun begin to die.

The star will expand into a massive red giant, and its gases drift off into space, forming a nebula.

Eventually the star collapses into a white dwarf – as seen with M27 - and eventually the colorful shell of gases will dissipate throughout the galaxy, leaving behind a solitary, tiny, dense, white dwarf star.

You are getting a peek into our Sun’s far-distant future when you observe this object!

Sagitta the Arrow is even smaller than Vulpecula – it’s the third smallest constellation in the sky! Located between the stars of Vulpecula and Aquila the Eagle, Sagitta’s stars resemble its namesake arrow.

It too contains an interesting deep-sky object: M71, an unusually small and young globular cluster whose lack of a strong central core has long confused and intrigued astronomers.

Your own views very likely won’t be as sharp or close as this. However, this photo does show the cluster’s lack of a bright, concentrated core, which led astronomers until fairly recently to classify this unusual cluster as an “open cluster” rather than as a “globular cluster.”

Studies in the 1970s proved it to be a globular cluster after all – though an unusually young and small one!

It’s visible in binoculars, and a larger telescope will enable you to separate its stars a bit more easily than most globulars; you’ll certainly see why it was thought to be an open cluster!

Delicate Delphinus the Dolphin appears to dive in and out of the Milky Way near Aquilla and Sagitta!

Many stargazers identify Delphinus as a herald of the fainter water constellations, rising in the east after sunset as fall approaches.

The starry dolphin appears to leap out of the great celestial ocean, announcing the arrival of more wonderful sights later in the evening.

With a large telescope and dark skies, you can pick out globular clusters Caldwell 42 and Caldwell 47.

Want to hunt for more treasures? You’ll need a treasure map, and the Night Sky Network’s “Trip Around the Triangle” handout is the perfect guide for your quest!

https://science.nasa.gov/solar-system/skywatching/night-sky-network/the-summer-triangles-hidden-treasures/

https://nightsky.jpl.nasa.gov/download-view.cfm?Doc_ID=390

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Hubble Rings in a New Galactic View

Aug 16, 2024

The subject of this NASA/ESA Hubble Space Telescope image is situated in the Perseus Cluster, also known as Abell 426, 320 million light-years from Earth.

It’s a barred spiral galaxy known as MCG+07-07-072, seen here among a number of photobombing stars that are much closer to Earth than it is.

MCG+07-07-072 has quite an unusual shape for a spiral galaxy, with thin arms emerging from the ends of its barred core to draw a near-circle around its disk.

It is classified as an SBc(r) galaxy: the c denotes that its two spiral arms are loosely wound, each only performing a half-turn around the galaxy, and the (r) is for the ring-like structure they create.

Rings in galaxies come in quite a few forms, from merely uncommon, to rare and scientifically important! Lenticular galaxies are a type that sit between elliptical and spiral galaxies.

They feature a large disk, unlike an elliptical galaxy, but lack any spiral arms. Lenticular means lens-shaped, and these galaxies often feature ring-like shapes in their disks.

Meanwhile, the classification of “ring galaxy” is reserved for peculiar galaxies with a round ring of gas and star formation, much like spiral arms look, but completely disconnected from the galactic nucleus — or even without any visible nucleus! They’re thought to be formed in galactic collisions.

Finally, there are the famous gravitational lenses, where the ring is in fact a distorted image of a distant, background galaxy, formed by the ‘lens’ galaxy bending light around it.

Ring-shaped images, called Einstein rings, only form when the lensing and imaged galaxies are perfectly aligned.

https://science.nasa.gov/missions/hubble/hubble-rings-in-a-new-galactic-view/