Space

cross-posted from: https://lemmy.world/post/30686153

In the world of black holes, there are generally three size categories: stellar-mass black holes (about five to 50 times the mass of the sun), supermassive black holes (millions to billions of times the mass of the sun), and intermediate-mass black holes with masses somewhere in between.

While we know that intermediate-mass black holes should exist, little is known about their origins or characteristics—they are considered the rare "missing links" in black hole evolution.

The James Webb Space Telescope's deepest view of a single target yet depicts spinning arcs of light that are galaxies from the universe's distant past, the European Space Agency said Tuesday.

The new image took the world's most powerful telescope more than 120 hours to capture, making it the longest Webb has ever focused on a single target.

CAPE CANAVERAL, Fla. (AP) — Astronomers have discovered a strange new object in our Milky Way galaxy.

An international team reported Wednesday that this celestial object — perhaps a star, pair of stars or something else entirely — is emitting X-rays around the same time it’s shooting out radio waves. What’s more, the cycle repeats every 44 minutes, at least during periods of extreme activity.

Located 15,000 light-years away in a region of the Milky Way brimming with stars, gas and dust, this object could be a highly magnetized dead star like a neutron or white dwarf, Curtin University’s Ziteng Andy Wang said in an email from Australia.

Or it could be “something exotic” and unknown, said Wang, lead author of the study published in the journal Nature.

NASA’s Chandra X-ray Observatory spotted the X-ray emissions by chance last year while focusing on a supernova remnant, or the remains of an exploded star. Wang said it was the first time X-rays had been seen coming from a so-called long-period radio transient, a rare object that cycles through radio signals over tens of minutes.

Given the uncertain distance, astronomers can’t tell if the weird object is associated with the supernova remnant or not. A single light-year is 5.8 trillion miles.

By MARCIA DUNN

Updated 5:21 PM GMT+2, May 28, 2025

Video description excerpt:

In November 2023 Voyager 1 stopped communicating with Earth, the telemetry it was sending contained no information, but engineers working on the spacecraft could tell it was still listening. It would take months of experimenting to understand the problem and develop a fix using techniques that had never been employed before and designing software for a 50 year old computer using pen and paper.

cross-posted from: https://lemmy.world/post/30532739

There are currently two major approaches to calculating how fast our universe is expanding.

The first approach is to measure the remnant light left over from the Big Bang, which is still traveling across the universe. This radiation, known as the cosmic microwave background, informs astronomers about what the conditions were like at early times in the universe.

Freedman, the John and Marion Sullivan University Professor in Astronomy and Astrophysics, specializes in a second approach, which is to measure how fast the universe is expanding right now, in our local astronomical neighborhood. Paradoxically, this is much trickier than seeing back in time, because accurately measuring distances is very challenging.

Freedman's latest calculation, which incorporates data from both the Hubble Telescope and the James Webb Space Telescope, finds a value of 70.4 kilometers per second per megaparsec, plus or minus 3%.

That brings her value into statistical agreement with recent measurements from the cosmic microwave background, which is 67.4, plus or minus 0.7%. The work is published in The Astrophysical Journal.

According to data from the Hubble and James Webb Space Telescopes, the origins of the free-flying photons in the early cosmic dawn were small dwarf galaxies that flared to life, clearing the fog of murky hydrogen that filled intergalactic space..."They produce ionizing photons that transform neutral hydrogen into ionized plasma during cosmic reionization. It highlights the importance of understanding low-mass galaxies in shaping the Universe's history."...Scientists thought that the sources responsible for most of the clearing must have been powerful – huge black holes whose accretion produces blazing light, for example, and large galaxies in the throes of star formation (baby stars produce a lot of UV light)...Surprisingly, [JWST]'s observations now suggest that dwarf galaxies are the key player in reionization...""Despite their tiny size, these low-mass galaxies are prolific producers of energetic radiation, and their abundance during this period is so substantial that their collective influence can transform the entire state of the Universe.""