BAN #365: Talk at NWU Thursday, Big beautiful spiral galaxy

11 October 2021   Issue #365

October 11, 2021

[The planetary nebula M 2-9, winds from a dying star. Credit: NASA / ESA / Hubble Legacy Archive / Judy Schmidt]

About this newsletter

Ooo, meta

Ignoring the extra 5 hours, 48 minutes, and 46 seconds, I have now written as many issues of the Bad Astronomy Newsletter as there are days in a tropical year.

I have no idea what to make of it, but it feels kinda neat.

Upcoming Appearances/Shameless Self-Promotion

Where I’ll be doing things you can watch and listen to or read about

On Thursday evening (October 14) at 17:30 Central (US) time, I will be speaking at Northwestern University in Chicago for the CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics) Public Lecture Series. I’ll be talking about exoplanets, asking a question that is on a lot of people’s minds: Is Earth Special?

You can register to attend here, and there will be a livestream, too — when I get that link I’ll post it to Twitter.

[Banner for my talk on October 14 at NWU. Credit: CIERA/NWU]

This is my first in-person talk in a long, long time. I’ve done lots of virtual talks, which is still fun, but nothing beats being in front of a live audience and hearing them laugh at jokes or seeing their eyes widen at a particularly cool science fact. I miss it.

On the other hand this is also the first time I’ll be traveling anywhere via airplane in a long time too. Besides the obvious issues I also don’t think I remember how to pack. Hopefully I’ll remember to bring clean underwear, and also a copy of my talk.

If you’re in the Chicago area I hope you can come!

Blog Jam

What I’ve recently written on the blog, ICYMI

[Pluto’s atmosphere backlit by the Sun after New Horizons passed the icy world. From Thursday’s article. Credit: NASA/JHU-APL/SwRI ]

Pic o’ the Letter

A cool or lovely or mind-bending astronomical image/video with a short description so you can grok it

Sometimes when I talk about the Milky Way I note how big it is. The disk of our spiral galaxy is 120,000 light years across, and that’s bigger than the vast majority of galaxies in the Universe.

But some are bigger. Like, for example, NGC 1365, a barred spiral about 60 million light years away:

That’s a combination of images from Hubble, Gemini, and amateur data, which is something astrophotographer Robert Gendler is very good at assembling. It’s incredible (note that the newsletter is limited to 1000 pixels wide, so click that link above to get access to much larger versions).

NGC 1365 is part of the nearby Fornax galaxy cluster, a densely populated collection of galaxies second only to the Virgo cluster for richness in our cosmic neighborhood.

It’s a lovely galaxy, but it’s also friggin’ HUGE: The disk is about 200,000 light years across, so much larger than the Milky Way. Like our own galaxy there’s a rectangular-ish bar across the center in the nucleus, which is pretty common in spirals (I wrote about this in the blog a while back if you want more).

In the very center of NGC 1365 is a supermassive black hole, though it’s anemic for such a big galaxy; it’s only about 2 million times the mass of the Sun. That’s big, I mean duh, but the one in the center of the Milky Way, called Sgr A*, is twice that mass, and is considered undersized for us. The one in NGC 1365 should be way bigger. At the moment, why that is remains a mystery.

Incidentally, that black hole is spinning at about the maximum speed a black hole can, which is kinda neat. I wrote about that specifically back in 2013 (please excuse the weird formatting issues; some of my articles didn’t migrate to SYFY correctly) and more recently how black holes in general spin.

It’s also feeding on material falling into it, which heats up and spews out high-energy X-rays and such (though some astronomers have argued this emission may be due to vigorous star birth near its nucleus which can also create X-rays as newborn massive stars blast out stellar winds and explode as supernovae). This makes NGC 1365 an active galaxy, one with an exceptionally bright nucleus.

I find the spiral arms of NGC 1365 interesting. They’re widely flung, unlike our Milky Way’s more tightly wound up arms. The one to the upper left seems to fan out and then break up a bit as you look counterclockwise around it. That must be some sort of gravitational effect but I’m unclear what that is or why that happens. Perhaps it’s because of near passes by other galaxies in the cluster gravitationally tugging on the outer edges of the arms.

I don’t have any particularly profound insights into this galaxy; at least nothing I haven’t written about before (like here, or here, or here, or even here). It’s just that sometimes I think we all need to see a spectacular photo of a gorgeous spiral galaxy.

In my case, I always do.

Et alia

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