Brian Koberlein, Author at Universe Today

August 29, 2023August 29, 2023 by Brian Koberlein

Astronomers Precisely Measure a Black Hole's Accretion Disk

How astronomers can measure the width of an accretion disk. Credit: NOIRLab/NSF/AURA/P. Marenfeld

When you think of a black hole, you might think its defining feature is its event horizon. That point of no return not even light can escape. While it’s true that all black holes have an event horizon, a more critical feature is the disk of hot gas and dust circling it, known as the accretion disk. And a team of astronomers have made the first direct measure of one.

August 27, 2023August 27, 2023 by Brian Koberlein

The Early Universe Should Be Awash in Active Galaxies, but JWST Isn't Finding Them

Artist view of an active black hole in the early universe. Credit: Boston University/Cosmovision

For decades the most distant objects we could see were quasars. We now know they are powerful active black holes. Active galactic nuclei so distant that they resemble star-like points of light. It tells us that supermassive black holes in the early Universe can be powerful monsters that drive the evolution of their galaxies. We had thought most early supermassive black holes went through such an active phase, but a new study suggests most supermassive black holes don’t.

August 26, 2023August 26, 2023 by Brian Koberlein

Pulsars Detected the Background Gravitational Hum of the Universe. Now Can They Detect Single Mergers?

How can array of pulsars can pinpoint binary black holes. Credit: Carl Knox/OzGrav

Current gravitational wave observatories have two significant limitations. The first is that they can only observe powerful gravitational bursts such as the mergers of black holes and neutron stars. The second is that they can only observe these mergers for wavelengths on the order of hundreds to thousands of kilometers. This means we can only observe stellar mass mergers. Of course, there’s a lot of interesting gravitational astronomy going on at other wavelengths and noise levels, which has motivated astronomers to get clever. One of these clever ideas is to use pulsars as a telescope.

August 25, 2023August 25, 2023 by Brian Koberlein

A Giant Black Hole Destroyed a Star and Threw the Pieces Into Space

Illustration of the black hole ASASSN-14li. Credit: NASA/CXC/M.Weiss

When a black hole consumes a star, things can get quite messy. Take, for example, the event known as ASASSN-14li, where a massive star strayed too close to a supermassive black hole and paid the ultimate price.

August 24, 2023August 24, 2023 by Brian Koberlein

TESS Has Found Thousands of Possible Exoplanets. Which Ones Should JWST Study?

Artist rendition of a potential water-world exoplanet that might support advanced civilizations. Such life could advertise its existence via technosignatures from industrial or other activities. (Credit: ESA / Hubble / M. Kornmesser) — Artist rendition of a potential water-world exoplanet that might support life. Scientists could determine whether to explore this world based on its planetary entropy production. (Credit: ESA / Hubble / M. Kornmesser)

There are more than 5,000 confirmed exoplanets in our galaxy. That number is going to rise significantly in the next decade. The Transiting Exoplanet Survey Satellite (TESS) has already cataloged more than 4,000 candidate exoplanets, and the PLAnetary Transits and Oscillations of stars (PLATO) is scheduled to launch in 2026. We will soon have more than 10,000 worlds where life might be able to survive. It’s an amazing idea, but with so many exoplanets we don’t have the resources to search for life on all of them. So how do we prioritize our search?

August 23, 2023August 23, 2023 by Brian Koberlein

The Irony. ClearSpace-1 Couldn't Clean up Space Debris Because its Target Already Got hit by Space Debris, Creating Even More Space Debris.

Illustration of ClearSpace-1 capturing a piece of space debris. Credit: ClearSpace

We have a problem.

Ever since the launch of Sputnik 1 in 1957, we have been launching debris into space. Everything from space stations and large communication satellites to small CubeSats. With each launch, we also add things such as rocket parts and paint chips to the orbital pile. Right now there are more than a million objects orbiting Earth wider than a centimeter, and at least 130 million millimeter-sized objects. Most of it isn’t going to deorbit any time soon.

August 22, 2023August 22, 2023 by Brian Koberlein

When the Sun Dies, it Could Produce a Fantastic Ring in Space, Like This New Image From JWST

The Ring Nebula seen by JWST's Near-Infrared Camera (left) and Mid-Infrared Instrument (right). Credit: ESA/Webb, NASA, CSA, M. Barlow (University College London), N. Cox (ACRI-ST), R. Wesson (Cardiff University)

Planetary nebulae were first discovered in the 1700s. Legend tells us that through the small telescopes of the time, they looked rather planet-like, hence the name. Real history is a bit more fuzzy, and early objects categorized as planetary nebulae included things such as galaxies. But the term stuck when applied to circular emission nebulae centered around a dying star. As new observations show, planetary nebulae have a structure that is both simple and complex.

August 19, 2023August 19, 2023 by Brian Koberlein

A New Way to Measure the Expansion Rate of the Universe: Redshift Drift

Cosmological redshift depends upon a galaxy's distance. Credit: NASA/JPL-Caltech/R. Hurt (Caltech-IPAC)

In 1929 Edwin Hubble published the first solid evidence that the universe is expanding. Drawing upon data from Vesto Slipher and Henrietta Leavitt, Hubble demonstrated a correlation between galactic distance and redshift. The more distant a galaxy was, the more its light appeared shifted to the red end of the spectrum. We now know this is due to cosmic expansion. Space itself is expanding, which makes distant galaxies appear to recede away from us. The rate of this expansion is known as the Hubble parameter, and while we have a good idea of its value, there is still a bit of tension between different results.

August 18, 2023August 18, 2023 by Brian Koberlein

A New Simulation Reveals One Entire Stage of a Star's Life

The interior structure of our Sun. Credit: Kelvin Ma, via Wikipedia

Nuclear fusion is at the center of stellar evolution. Most of a star’s life is a battle between gravity and nuclear power. While we understand this process on a broad scale, many of the details still elude us. We can’t dive into a star to see its nuclear furnace, so we rely on complex computer simulations. A recent study has made a big step forward by modeling the entire fusion cycle of a single element.

August 17, 2023August 17, 2023 by Brian Koberlein

We Might Be Able to Measure Dark Energy Through the Milky Way's Collision With Andromeda

How the sky might look when the Andromeda galaxy approaches the Milky Way. Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger

The Universe is expanding, and it’s doing so at an ever-increasing pace. Whether due to a dark energy field throughout the cosmos or due to a fundamental of spacetime itself, the cosmos is stretching the space between distant galaxies. But nearby galaxies, those part of our local group, are moving closer together. And how they are falling toward each other could tell us about the nature of cosmic expansion.