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Study reports that age is the driving force in changing how stars move within galaxies –

Study reports that age is the driving force in changing how stars move within galaxies

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Galaxies get more chaotic as they age
A comparison of a young (top) and old (bottom) galaxy observed as part of the SAMI Galaxy Survey. Panels on the left are regular optical images from the Subaru Telescope. In the middle are rotational velocity maps (blue coming towards us, red going away from us) from SAMI. On the right are maps measuring random velocities (redder colors for greater random velocity). Both galaxies have the same total mass. The top galaxy has an average age of 2 billion years, high rotation and low random motion. The bottom galaxy has an average age of 12.5 billion years, slower rotation and much larger random motion. Credit: Subaru credit: Image from the Hyper Suprime-Cam Subaru Strategic Program

Galaxies start life with their stars rotating in an orderly pattern but in some the motion of stars is more random. Until now, scientists have been uncertain about what causes this—possibly the surrounding environment or the mass of the galaxy itself.

A new study, published in MNRAS (Monthly Notices of the Royal Astronomical Society), has found that the most important factor is neither of these things. It shows the tendency of the stars to have random motion is driven mostly by the age of the galaxy—things just get messy over time.

“When we did the analysis, we found that age, consistently, whichever way we slice or dice it, is always the most important parameter,” says first author Prof Scott Croom, an ASTRO 3D researcher at the University of Sydney.

“Once you account for age, there is essentially no environmental trend, and it’s similar for mass.

“If you find a young galaxy it will be rotating, whatever it is in, and if you find an old galaxy, it will have more random orbits, whether it’s in a dense environment or a void.”

The research team also included scientists from Macquarie University, Swinburne University of Technology, the University of Western Australia, the Australian National University, the University of New South Wales, the University of Cambridge, the University of Queensland, and Yonsei University in the Republic of Korea.

The study updates our understanding from previous studies that have variously suggested environment or mass as more important factors. But the earlier work is not necessarily incorrect, says second author Dr. Jesse van de Sande.

Young galaxies are star-forming super-factories, while in older ones, star formation ceases.

“We do know that age is affected by environment. If a galaxy falls into a dense environment, it will tend to shut down the star formation. So galaxies in denser environments are, on average, older,” Dr. van de Sande says.

“The point of our analysis is that it’s not living in dense environments that reduces their spin, it’s the fact that they’re older.”

Our own galaxy, the Milky Way, still has a thin star forming disk, so is still considered a high spin rotational galaxy.

“But when we look at the Milky Way in detail, we do see something called the Milky Way thick disk. It’s not dominant, in terms of light, but it is there and those look to be older stars, which may well have been heated from the thin disk at earlier times, or born with more turbulent motion in the ,” Prof Croom says.

The research used data from observations made under the SAMI Galaxy Survey. The SAMI instrument was built in 2012 by the University of Sydney and the Anglo-Australian Observatory (now Astralis). SAMI uses the Anglo-Australian Telescope, at Siding Spring Observatory, near Coonabarabran, New South Wales. It has surveyed 3,000 galaxies across a large range of environments.

The study allows astronomers to rule out many processes when trying to understand galaxy formation and so fine-tune models of how the universe has developed.

The next steps will be to develop simulations of galaxy evolution with more granular detail.

“One of the challenges of getting simulations right is the high resolution you need in to predict what’s going on. Typical current simulations are based on particles which have the mass of maybe 100,000 stars and you can’t resolve small-scale structures in galaxy disks,” Prof. Croom says.

The Hector Galaxy Survey will help Prof Croom and his team expand this work using a new instrument on the Anglo-Australian Telescope.

“Hector is observing 15,000 galaxies but with higher spectral resolution, allowing the age and spin of galaxies to be measured even in much lower mass galaxies and with more detailed environmental information,” says Professor Julia Bryant, lead of the Hector Galaxy Survey, University of Sydney.

Professor Emma Ryan-Weber, Director of ASTRO 3D, says, “These findings answer one of the key questions posed by ASTRO 3D: how does mass and angular momentum evolve in the universe? This careful work by the SAMI team reveals that the age of a galaxy determines how the stars orbit. This critical piece of information contributes to a clearer big-picture view of the universe.”

More information:
Scott Croom et al, The SAMI Galaxy Survey: galaxy spin is more strongly correlated with stellar population age than mass or environment, Monthly Notices of the Royal Astronomical Society (2024). DOI: 10.1093/mnras/stae458. … 0.1093/mnras/stae458

Provided by
ARC Centre of Excellence for All Sky Astrophysics in 3D (ASTRO 3D)

Study reports that age is the driving force in changing how stars move within galaxies (2024, April 2)
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Study sheds new light on origin of fast radio bursts –

The long-time exposure photo taken on July 25, 2022 shows a night view of China’s Five-hundred-meter Aperture Spherical Radio Telescope (FAST) under maintenance in southwest China’s Guizhou Province. [Photo/Xinhua]

A Chinese research team has introduced a novel method for a comprehensive analysis of the behaviors of active fast radio bursts (FRBs) in the time-energy domain and revealed the randomness of the behaviors.

FRBs are intense pulses of radio emission that last just a few milliseconds. The origin of these brightest cosmic explosions in radio bands remains unknown.

Based on the rich data of China’s Five-hundred-meter Aperture Spherical radio Telescope (FAST), a research team at the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) proposed a new analysis framework that is able to quantify the randomness and chaotic nature of the bursting events.

The study reveals that the FRBs’ behaviors in the time-energy domain are fundamentally different from those of common transient physical phenomena such as earthquakes and solar flares, and exhibit a high degree of randomness like a Brownian motion, shedding new light on the origin of FRBs.

The excellent observation capabilities of FAST, combined with innovative analytical methods, will enable in-depth study of mysterious burst signals in the universe, which is expected to eventually reveal their origin, said Li Di, from NAOC, who led the study.

The study was published Friday as a cover paper in the journal Science Bulletin.

<!–enpproperty 1171244262024-04-14 14:44:34:0Study sheds new light on origin of fast radio burstsChina,FAST,Astronomy10077075074NationNation Chinese research team has introduced a novel method for a comprehensive analysis of the behaviors of active fast radio bursts in the time-energy domain.101弓迎春/enpproperty–>

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Star Diary: Comet 12P/Pons-Brooks reaches its brightest (15 to 21 April 2024) – Sky at Night Magazine

Comet 12P/Pons-Brooks reaches perihelion, its closest approach to the Sun this week, and should be at its brightest. Find out how you can see them for yourself as well as our usual stargazing highlights in this week’s podcast guide, Star Diary, 15 to 21 April 2024.

Find Star Diary in your favourite podcast player now

Chris: Hello and welcome to Star Diary, the podcast from the makers of BBC Sky at Night Magazine. You can subscribe to the digital edition of the magazine by visiting iTunes, Google Play, or Apple News, or to the print edition by visiting

Ezzy: Greetings listeners, and welcome to Star Diary. A weekly guide to the best things to see in the northern hemisphere’s night sky. As we are based here in the UK, all times are in BST. In this episode, we’ll be covering the coming week from 15 to 21 April. I’m Ezzy Pearson, the magazine’s features editor and I’m joined on the podcast today by Katrin Raynor, an astronomer and astronomy writer.

Hello, Katrin.

Katrin: Hello, Ezzy. How are you?

Ezzy: I’m doing well. So what do we have coming up in this week’s night sky?

Katrin: As we pass the middle of April, we have the start of another meteor shower and a planetary conjunction, which is going to be tricky to observe. The Moon is going to delight us this week with a few clair obscur effects, which appeal to adults and younger observers alike.

You know, they’re real… great fun to spot. So the Solar System, well, on 19th, the Eta Aquarid meteor shower begins. But it doesn’t peak until the beginning of May, when it may be possible to see around 50 meteors per hour.

So these meteors originate from the consultation of Aquarius and is debris left over from Halley’s comets.

Unfortunately, the shower is more prominent in the southern hemisphere and appears in the early pre dawn hours at northerly latitudes. But it will be possible to see some meteors in the eastern sky.

And conjunction wise with the planets, on 20th we have Jupiter and Uranus. They’re reaching conjunction, separated by just half a degree. And they’re going to be low on the western horizon in the dusk glow.

Bright Jupiter will be easy to spot, however Uranus is going to be a bit more tricky. So grab a pair of binoculars or a telescope to see the conjunction after 9PM BST. And Comet Pons-Brooks passes into the constellation of Taurus the Bull.

Speaking of the comets, Comet Pons-Brooks reaches perihelion on 21st.

So perihelion is when an orbiting body passes at its closest point to the Sun. And the comet should be at its predicted maximum brightness of magnitude +4.5, which means it may be visible with the naked eye in the western horizon. Perihelion, I think my astronomy teacher a few years ago, to remember perihelion and aphelion. He always said, perihelion meaning perilous, it’s close to the Sun.

So I also, that was a really good way of remembering.

Ezzy: Yeah. That is one that took me a while to get my head around. For me, it’s aphelion is it’s afar. Which is… I think yours is better.

Katrin: Yeah. Peri. Perilous. It’s going to get burned up by the S

un or something. I don’t know. It’s too close.

Ezzy: Yeah. The thing I always get slightly mixed up in my brain is the fact that when it’s a perihelion, it doesn’t necessarily mean it’s hidden behind the Sun.

Because to me, it’s like when it’s its closest, oh, that must be when it’s on the other side of the Sun. But that’s not actually what happens at all because of the way that our orbits are aligned and everything like that. Sometimes we can be looking at it sideways on when it’s passing close to the Sun.

Sometimes, comets do pop behind the Sun for a bit and can’t see them. But we should be able to see it when it’s passing through perihelion.

Katrin: And similar to that, actually, I will think if it’s closer to Earth. Then we’ll be able to see it better, but obviously that’s not the case. So there’s always like these nuances and it’s like, ooh.

Ezzy: When it’s closer to the Sun it’s giving off more gas. It’s hotter so it’s giving off more gas and more dust. So it’s got a bigger tail and coma and we can see it and it’s more bright. But it’s also sometimes further away than other times. And it’s this kind of like balance. And also comets are just notoriously unpredictable.

Katrin: They are.

Ezzy: You’re never sure what they’re going to do. I mean, it might be that comet Pons-Brooks doesn’t survive its encounter with perihelion. Sometimes comets do just break up. Hopefully it won’t, hopefully we’ll have a couple more weeks of it gracing our night skies still to come.

Katrin: Yes, I mean we deserve a good comet, don’t we really. But just to say it is going to be a challenging object to view in the twilight sky. By the end of the month it’s going to disappear into the evening twilight, so make the most of any clear nights to get out and observe it.

So the Moon, we have a couple of clair obscur effects to look out for this week. If you’re not familiar with this term, clair obscur is the interplay of light and shadow as the Moon changes its phases. So it’s possible to see faces, letters, and star clusters on the Moon caused by the changing light and shadow.

And as I mentioned earlier, these are  just great effects to spot. They’re real fun. I think, you know, it’s a good opportunity for kids to get involved. It might spark their interest. And yeah, I’ve seen, you know, a few of these effects now. And I remember the first time I saw Lunar X and V, I was like, “Oh,” yeah, you know, you can see the actual, the letters on the Moon.

It was brilliant.

Ezzy: Some of them are definitely easier to see than others. And some of them are much more obvious. Like, why is the Lunar X called the Lunar X? Because it looks like an X. So you know what you’re looking for.

Katrin: Yeah. I mean, a bit like the Jewelled Handle effect. I’m like, oh, it’s going to be bright and sparkly, but you know, it’s not. But worthwhile seeing. And I will be talking about this in a minute.

But 16 April, we have two effects to look out for on the morning of 16th as the Moon starts to set in the western sky. So we have Lunar X and Lunar V. It should be visible along the terminator. And the terminator is the line separating the light and the dark sides of the Moon.

So the X appears when sunlight skims the rims of the adjoining craters, Blanchinus, La Caille and Purbach at the same time, so their interiors are still steeped in shadow. Excuse my pronunciation there. I think we were talking earlier, weren’t we Ezzy, that because astronomy can be a lone hobby, if you like. Sometimes when you’re coming across these words, you’ve got no one to turn to and say, “well, how do I pronounce these?”

Ezzy: It also doesn’t help that it’s so many things are just a mismatch of all these different languages. You know, you’ve got some which are French and some which are Latin. Then there’s occasional Arabic one gets chucked in there as well, some Chinese. It’s just, I don’t know what pronunciation scheme I’m following here.

So, I think, just try your best.

Katrin: Sure and people pronounce them differently as well, don’t they? So it’s a bit like the tom-ah-to, tom-ay-to thing.

Ezzy: Yeah.

Katrin: But, you know, they’re still right. We’re both right, no matter how you pronounce it.

Farther north along the terminator, look for the Lunar V at the same time.

The slanted sunlight highlights two converging ridges of Mare Imbrium ejecta and the eroded rims of the craters Ukert M and N, located just east of Ukert. So I think you are going to have to kind of take to the internet or dig out your Moon map to locate these craters. There’s so many on the Moon, you know, if I was trying to tell you how to view these now, I’d probably be here for a long time.

Ezzy: Well, as usual, we have guides on how to locate the Lunar X and the Lunar V, and many craters on the Moon as well, over on our website, So if you are trying to find anywhere in particular, that’s always a good place to start.

Katrin: Moving on to 18th, so two days later after you’ve hopefully managed to spot Lunar X and Lunar V, the Jewelled Handle will be visible, which is best through binoculars or a small telescope.

So if you locate the 77% waxing gibbous Moon around 7PM BST, you’ll be able to see the illuminated arc of the Jura Mountains that border Sinus Iridum, the Bay of Rainbows, which is a semi circular bay located on the northwest region of the Moon. And I do think the Jewelled Handle will probably be a lot easier to spot than Lunar X and V.

So yeah, a lot to see, I think, on the Moon. Lots of exciting effects. So keep an eye out for.

Ezzy: Yeah, I think it’s also one of those things that’s really lovely about the Moon is because not only does it have these phases, which it changes every day, because it’s also got the libration. So that’s sort of like the Moon’s wobble a bit.

No two months are the same, even if you’re looking at when the sort of like the same phase, the light and the shadow is always slightly different. So it does change when you’re looking at it. So it’s well worth having a closer look at the Moon whenever you can.

Katrin: Like I said a few weeks ago, you know, I just, I love looking at the Moon, except when there is a meteor shower happening around the time.

Ezzy: Except when there’s a meteor shower.

Katrin: I think the Moon’s a bit like Marmite then, isn’t it? You either love it or hate it.

Ezzy: I think you sometimes love it and you sometimes hate it.

Katrin: Yes. We’re loving it this week. So just to end the week on 16th, this week’s dark sky object will create a real buzz, which is a terrible joke, because I’m going to talk about the Beehive Cluster.

So whilst you’re out on the night of 16th looking for Lunar X and V, take a trip to the constellation of Cancer to see the 60% waxing Moon, and sitting 3.3º northeast of M44, which is the Beehive Cluster, and it’s an open star cluster and one of the closest star clusters to Earth. I think Mary may have mentioned this a few weeks ago, so grab a pair of binoculars. Locate your gaze downwards from the Moon to find this area of glittering stars.

It is possible to see the cluster with the naked eye from dark sky sites, but it’s a popular pit stop for astronomers when conjunctions with the Moon or planets occur.

Ezzy: We often talk about when the Moon’s going to be passing the Beehive Cluster because the two do look very good together. Yeah. And as usual, if anybody does take a picture of that or any of the other things we’ve mentioned this week, please do send them in to us at Find the details in the notes below. We always love seeing your images and we print the best pictures in the magazine every month.

So hopefully there’ll be something in this week’s night sky that you’ll be able to get out there and have a look at. And thank you, Katrin, for taking us through all of them.

If at home you want to make sure that you are kept up to date with all of the latest goings on in the night sky, please do subscribe to the podcast and we will hopefully see you here next week.

But to just summarise this week again, we start off on 19th with the Eta Aquarid meteor shower which will just be beginning on 19th.

On 20th, Jupiter and Uranus are going to be in conjunction, so you get to see the two of those together.

On 21st, Comet Pons-Brooks is going to be reaching perihelion and will be at its brightest. It’s going to be disappearing out of our skies in the next couple of weeks, so definitely try to get a glimpse of that whilst you still can.

Over on the Moon, we’ve got several clair obscur effects which are definitely worth looking for. On 16 April, the Lunar X and V will both be visible along the terminator.

On the 18th, the Jewelled Handle will be on show near to the Bay of Rainbows.

And finally, on 16th as well, look out towards the Beehive Cluster where you’ll be able to see it next to the 60% waxing Moon.

So lots of really good things to see in the night sky. Thank you very much again  Katrin for taking us through all of those and we’ll hopefully see all of you back here next week. Goodbye!

If you want to find out even more spectacular sights that will be gracing the night sky this month, be sure to pick up a copy of BBC Sky at Night magazine where we have a 16 page pull out sky guide with a full overview of everything worth looking up for throughout the whole month. Whether you like to look at the Moon, the planets, or the deep sky.

Whether you use binoculars, telescopes, or neither, our sky guide has got you covered. With detailed star charts to help you track your way across the night sky. From all of us here at BBC Sky at Night Magazine, goodbye.

Chris: Thank you for listening to this episode of the Star Diary podcast from the makers of BBC Sky at Night Magazine.

Which was edited by Lewis Dobbs. For more of our podcasts, visit our website at, or head to Spotify, iTunes or your favorite podcast player.

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Deals: Samsung Galaxy A55 and A35 prices fall – news –

In the last week of March, Amazon Germany offered a free storage upgrade for the Galaxy A55, so the 128GB and 256GB models both cost the same – €480. Now that is over, but the two versions cost less.

The 256GB model is down to €460 and now getting the 128GB one actually makes sense as its price is down to €400. The Galaxy A55 has a microSD slot, so it’s easy to add more storage if you need it. The A55 has a premium build, great battery life and the Samsung/AMD chipset is both fast and stable under sustained load.

There’s also the Samsung Galaxy A35. It has the same display (Gorilla Glass Victus+ and all), but it uses the older Exynos 1380 chipset. And the 128GB model has only 6GB of RAM, you need to go up to the 256GB version if you want 8GB RAM (which is a bit pricey at the moment). That aside, the two phones are more similar than they are different.

For a more detailed comparison, check out our Galaxy A55 vs. Galaxy A35 article.

The Samsung Galaxy S23 FE is touted as an alternative to the A55 in some regions, but that doesn’t work in Germany. The 128GB model is €160 more than the A55 and the extra performance of the Exynos 2200 isn’t worth it, in our opinion. The poor battery life is a major downside and the 10MP 3x telephoto camera doesn’t quite make up for it.

The Realme 12 Pro+ is one to check out if zoom on a budget is something you want. It has a 3x periscope (71mm) with a 64MP sensor behind it. 3x shots turn out great in almost all lighting conditions, 6x shots are okay, but you need a stead hand. Anyway, the Realme also brings a 50MP main (1/1.56”, OIS) and 8MP ultra wide (112°), plus a 32MP selfie (22mm lens). It features a 6.7” 120Hz FHD+ AMOLED display, a Snapdragon 7s Gen 2 chipset and a 5,000mAh battery with 67W fast charging.

The Honor 90 Lite is half the price, but boasts a 100MP main camera. It’s also responsible for zooming, since there is no dedicated tele lens. This phone has a 6.7” 90Hz IPS LCD (FHD+) and a Dimensity 6020 for 5G connectivity, plus a 4,500mAh battery with 35W fast charging. We almost didn’t mention the 5MP ultra wide camera, but it barely deserves mentioning.

Amazon has a weird combo on offer – Samsung Galaxy Tab A9 or Tab A9+ with a pair of Galaxy Buds Pro 2. You can have just the tablets for €100 less, but the headphones cost €140 on their own, so there are some savings to be had. There are versions with Wi-Fi and with cellular connectivity, but note that the plus model has 5G, while the regular A9 only has 4G.

The Lenovo Legion Go takes the Ryzen Z1 Extreme that we’ve seen in the Asus ROG Ally, but makes the controllers detachable like on the Nintendo Switch. Also, this one packs an 8.8” LCD with QHD+ resolution and 144Hz refresh rate, so it has the edge on the Ally.

Remember LG? They may have bailed on smartphones, but they still make accessories. Check out the LG Tone Free DT80Q TWS buds. They have ANC and Dolby tech on board, both Atmos and Dolby Head Tracking. The sound processing is develop by the British audio pioneers Meridian.

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