Kevin Hardegree-Ullman
@kevinkhu.bsky.social
Research Scientist at Caltech/IPAC-NExScI studying all things related to exoplanets! Opinions are my own. https://kevinkhu.com
Pinned
Scaling K2 VIII: Short-Period Sub-Neptune Occurrence Rates Peak Around Early-Type M Dwarfs
We uniformly combined data from the NASA Kepler and K2 missions to compute planet occurrence rates across the entire FGK and M dwarf stellar range. The K2 mission, driven by targets selected by guest ...
arxiv.org
Kepler mission: smaller stars have more short-period, small #exoplanets.
Theory: the smallest stars won’t have enough disk material to make small planets so there must be a turnover.
Kepler+K2: We have found a turnover!
Check out our newest Scaling K2 paper: arxiv.org/abs/2508.05734
🧵 1/9
🔭🧪☄️
Theory: the smallest stars won’t have enough disk material to make small planets so there must be a turnover.
Kepler+K2: We have found a turnover!
Check out our newest Scaling K2 paper: arxiv.org/abs/2508.05734
🧵 1/9
🔭🧪☄️
Despite not being a professor, I do actually love guest lecturing about #exoplanets!
November 14, 2025 at 4:11 PM
Despite not being a professor, I do actually love guest lecturing about #exoplanets!
You know a country has a gun problem when this is being sold to 3-year-olds in a store called "The Baby Shop."
November 14, 2025 at 1:57 AM
You know a country has a gun problem when this is being sold to 3-year-olds in a store called "The Baby Shop."
Interesting timing. Today, Caltech sent an email call for nominations for the Richard P. Feynman Prize for Excellence in Teaching.
A few years ago I tried (and failed) to get them to rename the prize.
A few years ago I tried (and failed) to get them to rename the prize.
“I have decided that Feynman would have done what I did.. and I am therefore content.. no matter what..:)“
— Lawrence Krauss
🧪⚛️
— Lawrence Krauss
🧪⚛️
November 13, 2025 at 7:47 PM
Interesting timing. Today, Caltech sent an email call for nominations for the Richard P. Feynman Prize for Excellence in Teaching.
A few years ago I tried (and failed) to get them to rename the prize.
A few years ago I tried (and failed) to get them to rename the prize.
Reposted by Kevin Hardegree-Ullman
Brown. Dwarfs. Are. Purple.
Fixing what really matters (to me) on the NASA #Exoplanet Archive since December 2024. 🤣 🔭
Fixing what really matters (to me) on the NASA #Exoplanet Archive since December 2024. 🤣 🔭
Hey you. YES YOU. Super persnickety astronomer. You know who you are.
NASA Exoplanet Archive just updated our overview pages so the stars are closer to their actual colours, as per Harre & Heller (2021) and Cranmer (2021).
You're welcome. 😎
(You can thank @kevinkhu.bsky.social!)
NASA Exoplanet Archive just updated our overview pages so the stars are closer to their actual colours, as per Harre & Heller (2021) and Cranmer (2021).
You're welcome. 😎
(You can thank @kevinkhu.bsky.social!)
November 8, 2025 at 12:35 AM
Brown. Dwarfs. Are. Purple.
Fixing what really matters (to me) on the NASA #Exoplanet Archive since December 2024. 🤣 🔭
Fixing what really matters (to me) on the NASA #Exoplanet Archive since December 2024. 🤣 🔭
Reposted by Kevin Hardegree-Ullman
(To be clear, we also spruced up a bunch of other content and functionality on the overview pages, the first of a series of rolling updates, so do check them out!)
Updates are summarized here: exoplanetarchive.ipac.caltech.edu/docs/exonews...
Updates are summarized here: exoplanetarchive.ipac.caltech.edu/docs/exonews...
November 8, 2025 at 12:40 AM
(To be clear, we also spruced up a bunch of other content and functionality on the overview pages, the first of a series of rolling updates, so do check them out!)
Updates are summarized here: exoplanetarchive.ipac.caltech.edu/docs/exonews...
Updates are summarized here: exoplanetarchive.ipac.caltech.edu/docs/exonews...
Brown. Dwarfs. Are. Purple.
Fixing what really matters (to me) on the NASA #Exoplanet Archive since December 2024. 🤣 🔭
Fixing what really matters (to me) on the NASA #Exoplanet Archive since December 2024. 🤣 🔭
Hey you. YES YOU. Super persnickety astronomer. You know who you are.
NASA Exoplanet Archive just updated our overview pages so the stars are closer to their actual colours, as per Harre & Heller (2021) and Cranmer (2021).
You're welcome. 😎
(You can thank @kevinkhu.bsky.social!)
NASA Exoplanet Archive just updated our overview pages so the stars are closer to their actual colours, as per Harre & Heller (2021) and Cranmer (2021).
You're welcome. 😎
(You can thank @kevinkhu.bsky.social!)
November 8, 2025 at 12:35 AM
Brown. Dwarfs. Are. Purple.
Fixing what really matters (to me) on the NASA #Exoplanet Archive since December 2024. 🤣 🔭
Fixing what really matters (to me) on the NASA #Exoplanet Archive since December 2024. 🤣 🔭
Little kids are quite clever at naming things for which they do not know the word.
3 yo recovering from a 24 hr stomach bug: "Mommy, I want to keep my diaper on. I have melty poop."
🫠💩
3 yo recovering from a 24 hr stomach bug: "Mommy, I want to keep my diaper on. I have melty poop."
🫠💩
November 7, 2025 at 8:56 PM
Little kids are quite clever at naming things for which they do not know the word.
3 yo recovering from a 24 hr stomach bug: "Mommy, I want to keep my diaper on. I have melty poop."
🫠💩
3 yo recovering from a 24 hr stomach bug: "Mommy, I want to keep my diaper on. I have melty poop."
🫠💩
Reposted by Kevin Hardegree-Ullman
So I’m reviewing *post doc applications* and so far I’ve seen multiple applications with 30-80 papers. Astronomy what are you doing.
October 31, 2025 at 3:10 PM
So I’m reviewing *post doc applications* and so far I’ve seen multiple applications with 30-80 papers. Astronomy what are you doing.
The culture of "you must first-author publication(s) as an undergrad in order to succeed/get into grad school" is toxic and favors privileged students. It needs to stop. 🔭🧪
I'm writing an article now about a paper where an undergrad is the lead author, and I think it's not her first.
November 1, 2025 at 3:03 PM
The culture of "you must first-author publication(s) as an undergrad in order to succeed/get into grad school" is toxic and favors privileged students. It needs to stop. 🔭🧪
Halloween observations this year: kids prefer fruity candy over chocolate by at least 2:1. Also, nobody ever has, or ever will, like Almond Joy. 🎃
November 1, 2025 at 2:09 AM
Halloween observations this year: kids prefer fruity candy over chocolate by at least 2:1. Also, nobody ever has, or ever will, like Almond Joy. 🎃
Awesome, another paper of mine has reached 100 citations! 📜
October 24, 2025 at 9:33 PM
Awesome, another paper of mine has reached 100 citations! 📜
Thank you Colorado State University! Congrats on 60 years of the Madison-Macdonald Observatory! 🔭
October 18, 2025 at 3:37 AM
Thank you Colorado State University! Congrats on 60 years of the Madison-Macdonald Observatory! 🔭
Happening tomorrow!
Join me at Colorado State University's Madison-Macdonald Observatory 60th anniversary celebration on October 17th from 3-8:30 pm! 🔭
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
Madison-Macdonald Observatory’s 60th Anniversary – Department of Physics | CSU
www.physics.colostate.edu
October 16, 2025 at 11:36 PM
Happening tomorrow!
The NASA #Exoplanet Archive now has Gaia DR3 IDs! This should hopefully make your work and planning observations easier!
exoplanetarchive.ipac.caltech.edu
exoplanetarchive.ipac.caltech.edu
October 16, 2025 at 10:47 PM
The NASA #Exoplanet Archive now has Gaia DR3 IDs! This should hopefully make your work and planning observations easier!
exoplanetarchive.ipac.caltech.edu
exoplanetarchive.ipac.caltech.edu
It has been a while since I just got to "play" with a telescope! 🔭
October 15, 2025 at 4:01 AM
It has been a while since I just got to "play" with a telescope! 🔭
Reposted by Kevin Hardegree-Ullman
October 8, 2025 at 9:10 PM
Hey, that narrator sounds familiar!
Check out our new NASA #Exoplanet Archive homepage overview! 🔭
youtu.be/RHbvnodAX3g
Check out our new NASA #Exoplanet Archive homepage overview! 🔭
youtu.be/RHbvnodAX3g
A Quick Tour of the NASA Exoplanet Archive Homepage
YouTube video by NASA Exoplanet Archive
youtu.be
October 6, 2025 at 10:23 PM
Hey, that narrator sounds familiar!
Check out our new NASA #Exoplanet Archive homepage overview! 🔭
youtu.be/RHbvnodAX3g
Check out our new NASA #Exoplanet Archive homepage overview! 🔭
youtu.be/RHbvnodAX3g
Now I want a statistical survey of astronomers' favorite planets. But at least K2-138 made this article's list. 🤣
This week (!) is the 30th anniversary of the announcement of 51 Pegasi b, the first exoplanet found orbiting a star like our Sun - since then, we've found over 6,000!
To celebrate, @alexwitze.bsky.social and @nature.com collected some astronomers' favourite planets:
www.nature.com/articles/d41...
To celebrate, @alexwitze.bsky.social and @nature.com collected some astronomers' favourite planets:
www.nature.com/articles/d41...
These alien planets are astronomers’ favourites: here’s why
Space scientists look back on 30 years of exoplanet discoveries — from rows of massive ‘super-Earths‘ to worlds with perfectly synchronized orbits.
www.nature.com
October 3, 2025 at 2:47 AM
Now I want a statistical survey of astronomers' favorite planets. But at least K2-138 made this article's list. 🤣
Do you even lift?
October 3, 2025 at 1:52 AM
Do you even lift?
The Arecibo sky bridge, as seen from the secondary support structure in 2013. Sadly, this bridge no longer exists. 😞
September 26, 2025 at 7:10 PM
The Arecibo sky bridge, as seen from the secondary support structure in 2013. Sadly, this bridge no longer exists. 😞
Reposted by Kevin Hardegree-Ullman
Join me at Colorado State University's Madison-Macdonald Observatory 60th anniversary celebration on October 17th from 3-8:30 pm! 🔭
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
Madison-Macdonald Observatory’s 60th Anniversary – Department of Physics | CSU
www.physics.colostate.edu
September 26, 2025 at 12:10 AM
Join me at Colorado State University's Madison-Macdonald Observatory 60th anniversary celebration on October 17th from 3-8:30 pm! 🔭
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
Join me at Colorado State University's Madison-Macdonald Observatory 60th anniversary celebration on October 17th from 3-8:30 pm! 🔭
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
Madison-Macdonald Observatory’s 60th Anniversary – Department of Physics | CSU
www.physics.colostate.edu
September 26, 2025 at 12:10 AM
Join me at Colorado State University's Madison-Macdonald Observatory 60th anniversary celebration on October 17th from 3-8:30 pm! 🔭
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
There will be solar observing, physics demos, and stargazing, and I will be presenting a public lecture about #exoplanets!
www.physics.colostate.edu/about/astron...
Reposted by Kevin Hardegree-Ullman
I'm hiring at Haverford - a 2 year NASA funded postdoc to work on Galaxy Zoo with Roman Space Telescope Data: www.haverford.edu/human-resour... 👩🔬🔭
Postdoctoral Researcher in Extragalactic Astrophysics
Haverford College invites applications for our full-time (37.5 hours per week), fixed-term (2 year appointment), exempt, benefits-eligible Postdoctoral Research in Extragalactic Astrophysics opportuni...
www.haverford.edu
September 24, 2025 at 9:32 PM
I'm hiring at Haverford - a 2 year NASA funded postdoc to work on Galaxy Zoo with Roman Space Telescope Data: www.haverford.edu/human-resour... 👩🔬🔭
I gave a talk about my paper last month with this as the title slide. Can you tell I recently watched #Murderbot? 🔭 #Exoplanets
September 24, 2025 at 11:34 PM
I gave a talk about my paper last month with this as the title slide. Can you tell I recently watched #Murderbot? 🔭 #Exoplanets
You can access parameters for all 6,007 planets on the NASA Exoplanet Archive at exoplanetarchive.ipac.caltech.edu!
September 18, 2025 at 12:38 AM
You can access parameters for all 6,007 planets on the NASA Exoplanet Archive at exoplanetarchive.ipac.caltech.edu!