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Paul McMillan

@mcmillan-astro.bsky.social

Astrophysicist working on Milky Way dynamics and Gaia data. University of Leicester. Views expressed are my own. Website: https://paulmcmillan-astro.github.io/

2,334 Followers  |  124 Following  |  303 Posts  |  Joined: 07.07.2023  |  2.012

Latest posts by mcmillan-astro.bsky.social on Bluesky

UoL advert "We are researchers. teachers. activists. entrepreneurs. storytellers.

UoL advert "We are researchers. teachers. activists. entrepreneurs. storytellers.

Leicester UCU "NO TO STAFF CUTS"

Leicester UCU "NO TO STAFF CUTS"

The University of Leicester's marketing department know that it's the staff who are the lifeblood of the university. Leaving staff under threat of firing for months on end, with no negotiation with our representatives, is awful management

03.10.2025 10:30 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Me holding a protest banner. I think the grin is a bit cheesy.

Me holding a protest banner. I think the grin is a bit cheesy.

I'm not usually a much of a protestor, but I will try to defend the University of Leicester, and my colleagues, from the bad decisions made by our management. The proposed cuts unneeded, unfair and backed by cherry picked metrics. I support the @leicesterucu.bsky.social strike action.

30.09.2025 07:43 β€” πŸ‘ 9    πŸ” 2    πŸ’¬ 1    πŸ“Œ 0

I'm very sad that the university's leadership has brought us to this point. I will be joining my colleagues in striking to protect the future strength of the University of Leicester

26.09.2025 13:01 β€” πŸ‘ 4    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Today's entry in "Astronomers should't get to name things". Hubble's constant being constant in direction rather than time has always made it a bad name.

16.09.2025 14:59 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Exam text: Which provides evidence for the existence of dark energy?
Tick one box.
1. Some type 1a supernovae are brighter than expected.
2. Hubble's constant changes with time.
3. The light from some galaxies is blue-shifted.

Exam text: Which provides evidence for the existence of dark energy? Tick one box. 1. Some type 1a supernovae are brighter than expected. 2. Hubble's constant changes with time. 3. The light from some galaxies is blue-shifted.

Astronomers! This year’s A level physics exams included the following question which seems dodgy to me. Anyone got a sensible answer?

16.09.2025 13:50 β€” πŸ‘ 37    πŸ” 8    πŸ’¬ 17    πŸ“Œ 3

And it's bouncy. I rest my case.

12.09.2025 14:18 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

I think that's just years of preconceptions colouring her judgement.

12.09.2025 14:16 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Warthogs (not prancing)

Warthogs (not prancing)

Related note: Warthogs are delightful to watch because they prance when they run

12.09.2025 12:24 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
By JeffreyGammon - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=117070505

By JeffreyGammon - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=117070505

Personal opinion: Squirrels are cuter than other rodents because of the bouncy way they run, not because of the tail

12.09.2025 12:24 β€” πŸ‘ 4    πŸ” 0    πŸ’¬ 3    πŸ“Œ 0

πŸ”­πŸ§ͺ🎒 I'll be at the Leicester open day this Saturday. Maybe you can find out why my student feedback included being called an "S-tier" lecturer, which I had to look up, but is apparently positive! πŸ”­πŸ§ͺ🎒 le.ac.uk/open-days

09.09.2025 10:49 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

πŸ”­ On a related note: When students reach out to their former supervisors it can mean a lot to us. I'm going to write to my former Masters project supervisor and thank her. πŸ”­

04.09.2025 09:38 β€” πŸ‘ 6    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Figure illustrating a possible setup (not to scale) of J1901 in blue, with dipolar field lines emanating from the poles. The
AlfvΓ©n radius and Light cylinder radii are marked with dashed lines. In red is material that existed as a disk just after the merger,
which is falling back. Once it crosses the AlfvΓ©n radius, it follows the field line. In blue is the extraction process due to the potential
difference across the open field line at the light cylinder. In orange is a field line that is reconnecting close to the light cylinder.
Along this field line, the dashed-dotted orange wiggle represents the AlfvΓ©n wave due to the reconnection. We caution the reader
that while the AlfvΓ©n radius in the figure corresponds to a higher accretion rate than the rate derived from the X-rays, in which case
the AlfvΓ©n radius would be outside the light cylinder.

Figure illustrating a possible setup (not to scale) of J1901 in blue, with dipolar field lines emanating from the poles. The AlfvΓ©n radius and Light cylinder radii are marked with dashed lines. In red is material that existed as a disk just after the merger, which is falling back. Once it crosses the AlfvΓ©n radius, it follows the field line. In blue is the extraction process due to the potential difference across the open field line at the light cylinder. In orange is a field line that is reconnecting close to the light cylinder. Along this field line, the dashed-dotted orange wiggle represents the AlfvΓ©n wave due to the reconnection. We caution the reader that while the AlfvΓ©n radius in the figure corresponds to a higher accretion rate than the rate derived from the X-rays, in which case the AlfvΓ©n radius would be outside the light cylinder.

πŸ”­ One of the greatest pleasures of my job is when someone I helped and enthused at the start of their astrophysics studies finds success.

Congratulations ot Aayush Desai on publishing his first paper! arxiv.org/abs/2509.03216 πŸ”­

"Magnetic Atmospheres and Circumstellar Interaction in
J1901+1458"

04.09.2025 08:47 β€” πŸ‘ 8    πŸ” 0    πŸ’¬ 0    πŸ“Œ 1

πŸ”­πŸ§ͺ🎒 Reposting for the feeds 🎒πŸ§ͺπŸ”­

If you know/are an interested sixth-form student, our open day is a great way of seeing what you could be doing with us. I'll be there telling you about our work on the Milky Way!

le.ac.uk/open-days

28.08.2025 12:32 β€” πŸ‘ 3    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Sgt Pepper Beatles in NAM 2025 group photo

Sgt Pepper Beatles in NAM 2025 group photo

πŸ”­ Sgt Pepper's Lonely Hearts Club Band, UK astronomy version. Inspired by a comment from LOC chair David Alexander at #NAM2025 πŸ”­

15.07.2025 09:55 β€” πŸ‘ 14    πŸ” 2    πŸ’¬ 0    πŸ“Œ 0

πŸ”­ Exciting results from my colleagues πŸ”­

10.07.2025 16:34 β€” πŸ‘ 5    πŸ” 2    πŸ’¬ 0    πŸ“Œ 0
Prof Leigh Fletcher presenting results of JWST observations of Saturn

Prof Leigh Fletcher presenting results of JWST observations of Saturn

Prof Leigh Fletcher presenting results of JWST observations of Saturn

Prof Leigh Fletcher presenting results of JWST observations of Saturn

Our Prof @leighfletcher.bsky.social is giving a plenary talk at the National Astronomy Meeting presenting JWST observations of the solar system's gas giants! #NAM2025

09.07.2025 10:33 β€” πŸ‘ 8    πŸ” 1    πŸ’¬ 0    πŸ“Œ 0
The Thor Able rocket during NAM2025

The Thor Able rocket during NAM2025

A sighting of Leicester's @spacecentre.bsky.social Thor Able rocket during a really interesting (and last minute replacement!) talk by Dr Bleddyn Bowen on the politics of space at the UK's National Astronomy Meeting #NAM2025

07.07.2025 11:31 β€” πŸ‘ 4    πŸ” 0    πŸ’¬ 0    πŸ“Œ 1

(This post is not an endorsement of Botham's politics or of British beef)

07.07.2025 10:47 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Animated character "Beefy" used to sell British beef.

Animated character "Beefy" used to sell British beef.

Interesting start to #NAM2025 at a session dedicated to Galactic dynamics, and how "Basis function expansions" are useful tools for this. Speakers keep abbreviating this as BFE, pronounced "Beefy", which is a touch distracting

07.07.2025 10:46 β€” πŸ‘ 3    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0
Principle Skinner from The Simpsons. "Am I out of touch? No, it's the children who are wrong"

Principle Skinner from The Simpsons. "Am I out of touch? No, it's the children who are wrong"

Some student feedback on my lecturing described it as "S-tier", which I assumed meant it was very bad. It turns out to be the opposite, but I remain a bit baffled. The S does not stand for the word I would expect.

02.07.2025 13:44 β€” πŸ‘ 7    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

'if a forklift truck can pick it up, is it even worth lifting weights in the gym?'

30.06.2025 14:27 β€” πŸ‘ 6    πŸ” 2    πŸ’¬ 0    πŸ“Œ 0
Preview
Number of new UK entry-level jobs has dived since ChatGPT launch – research Vacancies for graduate jobs, apprenticeships, internships and junior jobs with no degree requirement have dropped 32%, Adzuna finds

Non-hot take: The "AI will kill us" discourse was a distraction from the real problem: it removes the young end of the skilled knowledge workforce. They are harder to train, because AI can do it for them. They can't get jobs, because AI can do it for their bosses. www.theguardian.com/business/202...

30.06.2025 13:59 β€” πŸ‘ 2    πŸ” 1    πŸ’¬ 0    πŸ“Œ 0
Preview
Pulp’s secret Glastonbury set review – still the magnificently misshapen oddballs of British pop Returning to headline the Pyramid for the first time in 30 years, Jarvis Cocker and co are as dark, grubby and joyous as ever, instantly turning the audience to misty-eyed displays of devotion

I am very much a child of the 90s. Watching the BBC's stream of this set gave me quite literal chills www.theguardian.com/music/2025/j...

30.06.2025 09:07 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

My lips are sealed. But we can expect incredible data! πŸ”­

27.06.2025 08:25 β€” πŸ‘ 11    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Our final call for expressions of interest for the STFC Rutherford Fellowships, with a deadline tomorrow - do get in touch if you have any questions!

25.06.2025 08:14 β€” πŸ‘ 2    πŸ” 5    πŸ’¬ 0    πŸ“Œ 0

πŸ”­ A compare and contrast that helped me understand how good the Vera Rubin images are:

24.06.2025 09:54 β€” πŸ‘ 18    πŸ” 2    πŸ’¬ 0    πŸ“Œ 0

The next open day for Physics degrees at the University of Leicester is Saturday 5th July πŸ§ͺ🎒

23.06.2025 12:32 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Video thumbnail

I designed and 3D printed my own floaty galaxy! πŸ”­πŸ§ͺ

23.06.2025 09:25 β€” πŸ‘ 44    πŸ” 2    πŸ’¬ 3    πŸ“Œ 0

There's nothing wrong with a Chaplin moustache!

12.06.2025 09:58 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Preview
Brian Wilson, visionary creative spirit for the Beach Boys, dies aged 82 Musician, who suffered from mental health problems, wrote and produced the 1966 album Pet Sounds – seen by many as the greatest album of all time

Brian Wilson was a genius. God Only Knows is the most incredibly beautiful song that YOU SHOULD NOT HAVE PLAYED AT YOUR WEDDING

www.theguardian.com/music/2025/j...

11.06.2025 18:39 β€” πŸ‘ 4    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

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