Refined stellar yardstick helps astronomers improve stellar evolution models

When you want to know the size of a room, you use a measuring tape to calculate its dimensions.

But you can’t use a tape measure to cover the inconceivably vast distances in space. And, until now, astronomers did not have an equally precise method to accurately measure distances to some of the oldest objects in our universe – ancient swarms of stars outside the disk of our galaxy called globular clusters.

Estimated distances to our Milky Way galaxy’s globular clusters were achieved by comparing the... Read more

Cosmic Quirk Boosts Far-Off Star’s Faint Glow

Through a quirk of nature called “gravitational lensing,” a natural lens in space amplified a very distant star’s light. Astronomers using Hubble took advantage of this phenomenon to pinpoint the faraway star and set a new distance record for the farthest individual star ever seen. They also used the distant star to test one theory of dark matter, and to probe the make-up of a galaxy cluster. The team dubbed the star “Icarus,” after the Greek mythological character who flew too near the Sun on wings of feathers and wax that melted. Its... Read more

Galaxy was expected to contain 400 times more dark matter than observations show

Grand, majestic spiral galaxies like our Milky Way are hard to miss. Astronomers can spot these vast complexes because of their large, glowing centers and their signature winding arms of gas and dust, where thousands of glowing stars reside.

But some galaxies aren't so distinctive. They are big, but they have so few stars for their size that they appear very faint and diffuse. In fact, they are so diffuse that they look like giant cotton balls.

Observations by NASA's Hubble Space Telescope of... Read more

Space Observatory Captures the Details of an Unusual Stellar Detonation

The universe is so huge that it's estimated that a star explodes as a supernova once every second. Astronomers capture a small fraction of these detonations because they are comparatively short-lived, like fireflies flickering on a summer evening. After skyrocketing to a sudden peak in brightness, a supernova can take weeks to slowly fade away.

For the past decade astronomers have been befuddled by a more curious "flash-in-the-pan" that pops up and then disappears in just a few days, not weeks. It's called... Read more

Ghostly-Looking Galaxy Stopped Making Stars Long Ago

The adventuring cinema archeologist Indiana Jones would be delighted to find a long-sought relic in his own backyard. Astronomers have gotten lucky enough to achieve such a quest. They identified a very rare and odd assemblage of stars that has remained essentially unchanged for the past 10 billion years. The diffuse stellar island provides valuable new insights into the origin and evolution of galaxies billions of years ago.

As far as galaxy evolution goes, this object is clearly a case of “arrested development.” The galaxy,... Read more

Newly discovered, vast, complex dust structure, about 150 billion miles across, envelopes the young star HR 4796A

Finding lots of dust around stars may not sound like anything astronomers would get excited about. The universe is a dusty place. But dust around a young star can be evidence that planet formation is taking place. This isn’t a new idea. In 1755, German Philosopher Immanuel Kant first proposed that planets formed around our Sun in a debris disk of gas and dust. Astronomers imagined that this process might take place around other stars.

They had to wait until the... Read more

New Survey Is the Most Precise Measurement of the Universe's Expansion Rate

The good news: Astronomers have made the most precise measurement to date of the rate at which the universe is expanding since the big bang. The possibly unsettling news: This may mean that there is something unknown about the makeup of the universe. The new numbers remain at odds with independent measurements of the early universe's expansion. Is something unpredicted going on in the depths of space?

Astronomers have come a long way since the early 1900s when they didn't have a clue that we lived in... Read more

Deep Survey Looks for Faint Objects in Nearby Stellar Nursery

Using NASA's Hubble Space Telescope to peer deep into the vast stellar nursery called the Orion Nebula, astronomers searched for small, faint bodies. What they found was the largest population yet of brown dwarfs — objects that are more massive than planets but do not shine like stars. Researchers identified 17 brown dwarf companions to red dwarf stars, one brown dwarf pair, and one brown dwarf with a planetary companion. They also found three giant planets, including a binary system where two planets orbit each other... Read more

Swarms of Young and Older Stars Yield Clues to our Galaxy’s Formation

Every star has a story to tell. Study a star and it will give you information about its composition, age, and possibly even clues to where it first formed. The stars residing in the oldest structure of our Milky Way galaxy, the central bulge, offer insight into how our pinwheel-shaped island of myriad stars evolved over billions of years. Think of our Milky Way as a pancake-shaped structure with a big round dollop of butter in the middle — that would be our galaxy’s central hub.

For many years, astronomers... Read more

Neutron Star Collision Cooks Up Exotic Elements, Gravitational Waves

When some people get in the kitchen, they create a delicious meal but leave behind a chaotic mess of splattered food and dirty dishes. Cosmic cookery can be just as messy. While a star can create chemical elements as heavy as iron within its core, anything heavier needs a more powerful source like a stellar explosion or the collision of two neutron stars.

Colliding neutron stars can yield gold, plutonium, and a variety of other elements. Theoretically, they also generate gravitational waves as they spiral... Read more