Kevin Hainline

Legally required to point out the Diner in Tom’s Diner is right under NASA’s Goddard Institute for Space Studies, where someone in the crowd during a 1967 talk by John Archibald Wheeler coined the term “black hole.”

talking at carnegie today with an astronomer about infrared selection of AGNs and she said "ah, so, [the technique] is reliable but not complete" and I think I want that as a t-shirt

RELIABLE
BUT NOT
COMPLETE

Oh also I owe a lot to the help of my co-authors @bemiles.bsky.social, @markmarley.bsky.social and @jarron.bsky.social because I’m ostensibly an extragalactic scientist. It’s so great to meet people who know a lot more than you do about anything (it’s a great reason for universities to exist)

Ok, so, I should correct myself: Tucson doesn't get to 120, but Phoenix has gotten up there. So imagine an object the size of Jupiter with an atmosphere the temperature of Arizona desert in the height of summer; *in JADES we could see this object even if it was 4000-5000 light years away.*

ANYWAY, BROWN DWARFS ARE PRETTY COOL

THIS IS A PLAY ON WORDS YES BUT ALSO THEY ARE COOL IN THE AESTHETIC SENSE

Two final plots. On the left is the brown dwarf number density (number of brown dwarfs in a given parsec cubed box) as a function of brown dwarf temperature, where multiple surveys show how low temperature brown dwarfs are more common than higher temperature ones. In the right panel we plot the number density against the height above the galaxy midplane, and we see how it drops off, which makes sense since the galaxy midplane is where the stellar density is highest.

Finally, with our sample and some from the literature, we can look at the number of these very cold brown dwarfs in a given volume of space as a function of both temperature and height above the galaxy. This will help people with modeling the mass of the galaxy, and the distribution of stars!

Four sets of plots showing "proper motion" for four different brown dwarf candidates. In each set of plots, there are two images of the same brown dwarf, taken separated by a number of years, and the sources move between when the images were taken, which is represented by circles that show the before and after positions.

We also see more proper motions for these brown dwarf candidates, where they are observed to move between images taken many years apart, which lends support to our claim that these aren't ultra distant galaxies, but much closer brown dwarfs.

A plot showing the best fit NIFTY metallicity for the brown dwarf candidates as a function of height above the galactic midplane, with the points from JADES as black circles, and points from other papers plottedi n grey. They seem to decline at large heights above (or below) the midplane, with median values shown as star points helping demonstrate this decline.

One interesting result from fitting these sources is that it looks like the brown dwarf atmospheric metallicity seems to decline for sources that are farther from the Milky Way disk, as we might expect, since these brown dwarfs are likely older, forming at earlier times. This is super neat!

The logo for NIFTY, which stands for Near Infrared Fitting for T and Y dwarfs, and the logo is the word NIFTY above these words, with a little brown dwarf standing in for the dot in the i in NIFTY.

Our fits are from a new fitting code I wrote with (my (former graduate student!) Jake Helton, Near Infrared Fitting for T- and Y-dwarfs, or NIFTY. It's Bayesian, and designed to fit NIRCam and MIRI data for brown dwarf candidates found in photometric data. It's here:

github.com/kevinhainlin...

Another plot from the survey, showing JADES-GS-BD-5, with the observed data points plotted as black points, and the fit as a squiggly line that matches the observed data points well. The distance we predict from the fit is only 70 parsecs, and the temperature is 322 Kelvin. Beneath the fit plot, there are thumbnails showing the object as seen in different NIRCam and MIRI filters, out to 12.8 microns.

We find these cold brown dwarfs all over the place in the survey. Some of them are so cold that their surface is about the same as what Tucson can get to in the summer. This object, JADES-GS-BD-5, which we observe with NIRCam and MIRI, has a temperature of 322 K, or only 120° Fahrenheit (49° C)!

A plot from my paper showing the fit temperatures for my brown dwarf sample as little black dots plotted against their temperatures. The sources in my paper are between 300 and 1200 Kelvin, and extend out to 5 - 7 kiloparsecs. There are other sources from the literature, which are closer, generally, and at higher temperatures.

I've taken quite an interest in finding these sources, since, with the depth of JWST NIRCam observations, you can find some really faint sources, many of which are stupendously cold. And a number are very distant - thousands of light years from the Earth, outside of the disk of the Milky Way.

An artist's rendition of The Sun, which is large and in the upper left, and then a low mass star, which is much smaller, and increasingly red, then a brown dwarf, which is also reddish, and smaller, then the large planet Jupiter, and finally the tiny lil' Earth in the bottom right.

See, it turns out that when you have incredibly deep infrared observations of hundreds of thousands of distant galaxies, sneaking around in these data are these super cold "failed stars," known as brown dwarfs, which are the link between stars and planets.

JADES: An Abundance of Ultra-Distant T- and Y-Dwarfs in Deep Extragalactic Data Ultra-cool T- (T$_{\mathrm{eff}} \approx$ 500 - 1200 K) and Y-dwarfs (T$_{\mathrm{eff}}$ $\lessapprox 500$ K) have historically been found only a few hundred parsecs from the Sun. The sensitivity and ...

I wrote another paper! And yes it's about brown dwarfs wait don't go anywhere they're really neat

arxiv.org/abs/2510.00111

a photograph of a road south of Tucson, Arizona, from google maps "street view," of a sign indicating the distances to the upcoming "Sahuarita Exits." There are three, Pima Mine Road, in 1 kilometer, Sahuarita Road, in 6 kilometers, and Duval Mine Road, in 12 kilometers. The thing is, the sign is provided in the metric system, this is one of the few roads in America where that is the case.

it's a slow process but we can get it done
maps.app.goo.gl/w8N21QRLemP8...

I went to a tiki bar once and as I came through the door a bartender was bringing a table of Adults a whole tray of Michelob Ultras, that was what they all ordered

why doesn’t the New York Times profile these people every month

The Core | Rotten Tomatoes Discover reviews, ratings, and trailers for The Core on Rotten Tomatoes. Stay updated with critic and audience scores today!

www.rottentomatoes.com/m/core

I unashamedly love this terrible movie

a blue triangle with sides labelled a, b, and then the hypotenuse is c. There are squares along each side that show how a^2 is 9, b^2 is 16, and c^2 is the sum of 9 and 16, 25. In the top it says a^2 + b^2 = c^2.

Today is my birthday, *and* it's a Pythagorean triple, 9 / 16 / 25. This sort of thing really got a lot of Greek mathematicians excited, until they had to reckon with what would happen to the length (c) if (a) and (b) were 1, that awful irrational square root of two.

his analysis and research is amazing but I actually published six first author papers in the last five years thank you very much

Yoshi (video game) - Wikipedia

I think he's probably just talking about Yoshi for the NES, the puzzle game. I don't know why he calls this a "sequel," but the game fits the timeline better than Yoshi's Cookie or Yoshi's Island. en.wikipedia.org/wiki/Yoshi_(...

A text from my father: “We just watched it. It’s great. Mom kept interrupting and recounting everything as if I knew none of this! And towards the end she said, and I quote, “At the end he should say ‘mom was right’!”

A text from my father after they sat down to watch the video:

I own a pair of these deep field socks, and they're what I've worn to so many public JWST talks and they always get a great reaction from folks who notice. I might have to pick up a second pair, not because mine have worn out, but just because I love them so much.

Yoshi (video game) - Wikipedia

I'm realizing maybe they're referring to the NES game "Yoshi", which could ... naively? be thought of as a "sequel" to Super Mario World, and lines up in the timeline. en.wikipedia.org/wiki/Yoshi_(...

Why would he go through so much effort to...dupe me? Why wouldn't he send the letter to more people? I've had the letter for *years.* The alternate is that I made it all up, but that would be a dumb/ruinous thing to do for a few hundred YouTube views.

YouTube video by Kevin Hainline Chris Houlihan Is Real

@jparish.bsky.social A number of years ago I stumbled on the story behind A Link to the Past's Chris Houlihan Room, including the letter sent to Chris from Nintendo Power. I finally decided to make a video about it all, in case you're interested.
youtu.be/SY00ri_a9y4?...

I don't subscribe to many conspiracy theories but I'm one of those people that thinks that this song should be the one called Flamenco Sketches on the album, and vice versa

it's just way too bouncy for a song called All Blues

the nfl logo in the crowd wearing a hat with rob Lowe’s face on it

Since we can see in all directions, the black hole in the galaxy that serves as the Cosmic Horseshoe lens is indeed one of the largest. There may be larger ones hidden by dust, but generally our idea of how SMBHs evolve indicate that's not super likely (and we have ways of seeing through dust).

Generally, if a black hole gets very large, it's because it's swallowing material at an incredible rate, making their effects (jets, disks) quite visible. And if you go significantly farther away (farther back in time), the Universe hasn't had enough time to build black holes this massive.

Every time I see your progress on this I am stunned, this is exquisite.

Oh disappointing I would have done it