Nick @internic@qoto.org

As you're freely falling through the air you don't feel any force except the wind - but you're also getting *stretched* a tiny amount because gravity is a bit stronger near your feet. This is called a 'tidal force' because it creates tides: for example, water on the side of the Earth facing the Moon is pulled toward the Moon more than water on the opposite side.

As a star falls toward a black hole it can get stretched and even destroyed by this tidal force - we've seen it happen! It can create a huge flare of radiation.

But surprisingly, the bigger the black hole, the smaller the tidal force is near the event horizon. We could be falling through the event horizon of a truly enormous black hole right now, and we'd never notice - though I consider this very unlikely.

More importantly, a star like the Sun will only get disrupted *before* it crosses the event horizon if the black hole is < 100 million solar masses. Otherwise it will get sucked in and be lost to sight without any drama!

The big black hole in the center of our galaxy is only 4 million solar masses, so this 'silent death' doesn't happen here. But it happens elsewhere. The biggest black hole known is 66 *billion* solar masses!

Black holes emit flares of light that we don't understand. Some must be from stars falling in. But many flares show very little light in hydrogen's spectral lines! This talk is pretty fun, and it's all about these mysteries.

https://www.youtube.com/watch?v=m6cFy34wsyM

On SciComm.xyz, we have a rule about the use of image description; there are good reasons for that.

The most important one is because we believe that people using screen-readers (or with sight-related problems) should be 1st-class citizens on the Fediverse and should not feel excluded by inaccessible content.

But there are also very down-to-earth reasons why scientists and science communicators should use image descriptions.

A thread.
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#accessibility #SciComm #science

Wizard Zines is doing another Big Zine Sale again this year on **Friday, November 29th**! One day only.

here’s a google calendar link for the duration of the sale if you want a reminder: https://wzrd.page/cal (or ical: https://wzrd.page/cal.ics)

I'm looking for some good resources on navigating conflict and difficult conversations in academia/science/the workplace for grad students and other early career researchers. Does that exist?

Hi all, I'm a french physicist from Marseille.

I work at the interface between statistical physics, network science and sociology (sometimes labelled #sociophysics or #ComputationalSocialScience). I'm basically interested in universal properties in human behaviour, and the mechanisms responsible for these properties.

I also teach maths, network science and Python in Aix-Marseille Univ.

a PSA since a lot of folks have been surprised to learn this: terminal programs often support the mouse! Try:

- opening `htop` and clicking a column header to sort
- opening `nano` (or vim, or micro) and clicking and dragging to select text
- using the scroll wheel in `mc` & clicking on the menus

it's really helpful if I forget a keyboard shortcut

Some friends are asking if I'll go to Bluesky. I don't want to, for reasons I'll explain. But people there can follow me at

@bsky.brid.gy

And if you're on Bluesky and follow @ap.brid.gy and let me know, I should be able to follow you from here. Details to follow, including my problems with Bluesky.

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One of my favorite things to do with students in the late fall is to take them outside and point first to the Orion nebula, then to the Pleiades, and finally to the Hyades cluster, saying, “These are snapshots in the evolution of open clusters.” Each of these systems is the home of young stars, but while the Orion nebula is very much a stellar nursery, with stars just 10 million years old or younger, the Pleiades, is more like a daycare center with stars 100 million years old or younger. At the same time, Hyades is more like an afterschool program for stars 730 million years old or younger. All these systems are filled with celestial children. In their youth, these stars still gather in clumps. But, as they age, the stars will drift apart until, as adults, they have no memory of the place they were born. Our Sun is one of these solitary stars and every time I introduce my students to these three open clusters, they ask what happened to the open cluster where our Sun was born.

The truth is, the cluster and our Sun had a falling out.

Read more on Substack
https://open.substack.com/pub/starstryder/p/our-suns-lost-family

I think it's ok to tell you now that @anthrocypher and I have been collaborating on a scientific paper, that might also be a the-beacons-are-lit-Gondor-calls-for-aid thesis, might be the boldest thing I've written in developer science so far, might be something that only could've been written out of the liminal spaces that Ana and I both inhabit, and out of the joy of deciding we wanted to try to articulate science & community of practice wisdom together in one place and see where it took us

Over the past 24 hrs while Mastodon was discoursing about whether or not starter packs are OK, and if slow progress is more due to lack of funding or different priorities, and if people that choose other social networks are just evil, lazy, shiftless people who love to lick VCs boots or are people that just want a better UX...

BlueSky added another 1 million users.

If you're on BlueSky and want to bridge to Mastodon, follow @ap.brid.gy

That's it. Nothing to install, no terms of service to sign, no complicated garbage. If you want to stop, just block @ap.brid.gy

Details here: https://fed.brid.gy/docs

If you want to bridge your account to BlueSky, simply follow this account: @bsky.brid.gy

Why am I encouraging this? Because when BlueSky inevitably goes bad, people there will have friends in the Fediverse to help them move here.

New review feat. THE Sapna Cheryan (essentially if you want to understand STEM gender equity gaps this is the scientist to read) free to access until Dec 2

"Global patterns of gender disparities in STEM and explanations for their persistence"

https://www.nature.com/articles/s44159-024-00380-3

I don't really know why people study astronomy in such great detail - except that it's fun. I think it's important to understand how the universe as we know it began about 14 billion years ago, and understand how the Earth was formed about 4.5 billion years ago, and how evolution brought us here. My life fits into this frame. But is it important to know the various dramatic ways that stars can die?

I don't think so... but it's sure fun!

Here's a tiny white dwarf star called a 'polar' sucking hot gas from its much larger but lighter companion. It's called a 'polar' because its magnetic field is so strong that the gas falling in is forced to move along the field lines, rather than forming the usual pancake-shaped 'accretion disk' and slowly spiralling in.

This means the ionized gas falling onto this white dwarf lands only on its north and south magnetic poles. It's like how ions from the Sun hit our Earth near its poles, producing auroras there. But it's vastly more intense! The magnetic field of a 'polar' is about 100 million times stronger than the Earth's magnetic field. And a lot more stuff is falling in. Now and then a *huge* amount.

So, polars are considered 'cataclysmic variable stars': now and then they blast out huge amounts of radiation, as a clump of infalling gas hits their surface. There are different kinds of cataclysmic variable stars. This is just one!

Now, why is it so fun to think about this... instead of, say, politics, or ecology? I guess the question answers itself. So now I'm wondering how much we can justify science based on escapism. Maybe a bit is okay. We need to have some fun, after all.

https://en.wikipedia.org/wiki/Polar_(star)