milky way Archives

August 29, 2024August 29, 2024 by Mark Thompson

Giant Low-Frequency Scan Searches for Aliens in 2,800 Galaxies

One of the tiles making up the 32T, a prototype instrument for the Murchison Widefield Array. Natasha Hurley-Walker

The search for extraterrestrial intelligence (SETI) has fascinated us for decades. Now a team of researchers have used the Murchison Widefield Array in Australia to scan great swathes of sky for alien signals. Unusually for a SETI project, this one focussed attention on 2,800 galaxies instead of stars within our own. They have been on the lookout for advanced civilisations that are broadcasting their existence using the power of an entire star. Alas they weren’t successful but its an exciting new way to search for alien intelligence.

August 12, 2024August 12, 2024 by Andy Tomaswick

Are Andromeda and the Milky Way Doomed to Collide? Maybe Not

Scientists discovered the Andromeda galaxy, known as M31, hundreds of years ago, and around a century ago, we realized that it had negative radial velocity toward the Milky Way. In other words, eventually, the two galaxies would merge spectacularly. That has been common knowledge for astronomers since then, but is it really true? A new paper from researchers at the University of Helsinki looks at several confounding factors, including the gravitational influence of other galaxies in our local group, and finds only a 50% chance that the Milky Way will merge with the Andromeda galaxy in the next 10 billion years.

July 8, 2024July 8, 2024 by Mark Thompson

Mapping the Milky Way’s Dark Matter Halo

The Galactic disk warp "dances gracefully" under the torque of the dark matter halo (an artistic impression created by Kaiyuan Hou and Zhanxun Dong from the School of Design, Shanghai Jiao Tong University).

Anytime astronomers talk of mapping the Milky Way I am always reminded how tricky the study of the Universe can be. After all, we live inside the Milky Way and working out what it looks like or mapping it from the inside is not the easiest of missions. It’s one thing to map the visible matter but mapping the dark matter is even harder. Challenges aside, a team of astronomers think they have managed to map the dark matter halo surrounding our Galaxy using Cepheid Variable stars and data from Gaia.

June 13, 2024June 13, 2024 by Mark Thompson

The Inner and Outer Milky Way Aren’t the Same Thickness, and that’s Surprising

Illustration depicting the Smith Cloud on its journey to the Milky Way Creator: NRAO/AUI/NSF Credit: B. Saxton, NRAO/AUI/NSF

At first glance, the universe and night sky seem largely unchanging. The reality is very different, even now, a gas cloud is charging toward the Milky Way Galaxy and is expected to crash into us in 27 million years. A team of astronomers hoping to locate the exact position of the expected impact site have been unsuccessful but have accidentally measured the thickness of the Milky Way! Analysing radio data, they have been able to deduce the thickness of the inner and outer regions and discovered a dramatic difference between the two.

May 30, 2024May 30, 2024 by Mark Thompson

Hot Gas is Being Vented Away from the Center of the Milky Way

X-Ray Data Revealing Jets at the Center of the Milky Way Credit: X-ray: NASA/CXC/Univ. of Chicago/S.C. Mackey et al.; Radio: NRF/SARAO/MeerKAT; Image Processing: NASA/CXC/SAO/N. Wolk

Studying gas in the Universe is no easy task. We often look to ‘non-visible’ wavelengths of the electromagnetic spectrum such as X-rays. The Chandra X-Ray observatory has been observing a vent of hot gas blowing away from the centre of the Milky Way. Located about 26,000 light years away, the jet extends for hundreds of light years and is perpendicular to the disk of the Galaxy. It is now thought the gas has been forced away from the centre of the Milky Way because of a collision with cooler gas lying in its path and creating shockwaves.

May 15, 2024May 15, 2024 by Mark Thompson

Three of the Oldest Stars in the Universe Found Circling the Milky Way

MIT astronomers discovered three of the oldest stars in the universe, and they live in our own galactic neighborhood. The stars are in the Milky Way’s “halo” — the cloud of stars that envelopes the main galactic disk — and they appear to have formed between 12 and 13 billion years ago, when the very first galaxies were taking shape. Credits:Image: Serge Brunier; NASA

Mention the Milky Way and most people will visualise a great big spiral galaxy billions of years old. It’s thought to be a galaxy that took shape billions of years after the Big Bang. Studies by astronomers have revealed that there are the echo’s of an earlier time around us. A team of astronomers from MIT have found three ancient stars orbiting the Milky Way’s halo. The team think these stars formed when the Universe was around a billion years old and that they were once part of a smaller galaxy that was consumed by the Milky Way.

May 10, 2024May 10, 2024 by Mark Thompson

Does the Milky Way Have Too Many Satellite Galaxies?

The Large and Small Magellanic Clouds are well known satellite galaxies of the Milky Way but there are more. It is surrounded by at least 61 within 1.4 million light years (for context the Andromeda Galaxy is 2.5 million light years away) but there are likely to be more. A team of astronomers have been hunting for more companions using the Subaru telescope and so far, have searched just 3% of the sky. To everyone’s surprise they have found nine previously undiscovered satellite galaxies, far more than expected.

April 26, 2024April 26, 2024 by Mark Thompson

Black Holes Can Halt Star Formation in Massive Galaxies

This research published in Nature is the first direct confirmation that supermassive black holes are capable of shutting down galaxies

It’s difficult to actually visualise a universe that is changing. Things tend to happen at snails pace albeit with the odd exception. Take the formation of galaxies growing in the early universe. Their immense gravitational field would suck in dust and gas from the local vicinity creating vast collections of stars. In the very centre of these young galaxies, supermassive blackholes would reside turning the galaxy into powerful quasars. A recent survey by the James Webb Space Telescope (JWST) reveals that black holes can create a powerful solar wind that can remove gas from galaxies faster than they can form into stars, shutting off the creation of new stars.

April 25, 2024April 25, 2024 by Mark Thompson

Mapping the Milky Way’s Magnetic Field in 3D

We are all very familiar with the concept of the Earth’s magnetic field. It turns out that most objects in space have magnetic fields but it’s quite tricky to measure them. Astronomers have developed an ingenious way to measure the magnetic field of the Milky Way using polarised light from interstellar dust grains that align themselves to the magnetic field lines. A new survey has begun this mapping process and has mapped an area that covers the equivalent of 15 times the full Moon.

April 17, 2024April 17, 2024 by Evan Gough

The Milky Way’s Most Massive Stellar Black Hole is Only 2,000 Light Years Away

This image shows the locations of the first three black holes discovered by ESA's Gaia mission in the Milky Way. Gaia Black Hole 1 (BH1) is located just 1560 light-years away from us in the direction of the constellation Ophiuchus; Gaia BH2 is 3800 light-years away in the constellation Centaurus; Gaia BH3 is in the constellation Aquila, at a distance of 1926 light-years from Earth. In galactic terms, these black holes reside in our cosmic backyard. Image Credit: ESA/Gaia/DPAC. Licence CC BY-SA 3.0 IGO

Astronomers have found the largest stellar mass black hole in the Milky Way so far. At 33 solar masses, it dwarfs the previous record-holder, Cygnus X-1, which has only 21 solar masses. Most stellar mass black holes have about 10 solar masses, making the new one—Gaia BH3—a true giant.