Mordecai-Mark Mac Low
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astrocurator.bsky.social
Mordecai-Mark Mac Low
@astrocurator.bsky.social
460 followers 250 following 330 posts
Researching the formation of planets, stars, and galaxies, mostly through numerical simulations. Curator-in-Charge, Dept. of Astrophysics, American Museum of Natural History. All opinions are my own and not the institution's.
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astrocurator.bsky.social
Well, the entire visible universe aside from the part blocked by that pesky rock it's sitting on (the grey area in this plot) community.lsst.org/uploads/defa...
Plot of the full sky in equatorial coordinates, showing the northern hemisphere almost entirely grey, while the southern hemisphere shows colors calibrated by a color bar to show 700 to 1200 visits over 10 years.
June 23, 2025 at 9:07 PM
astrocurator.bsky.social
The famously draft-dodging president violating 4 U.S. Code § 9 "Conduct during ... passing of flag":

"During the ceremony of hoisting or lowering the flag or when the flag is passing in a parade or in review, all persons present in uniform should render the military salute.
(1/2)
The President standing on a podium rendering a military salute.
June 15, 2025 at 1:11 AM
astrocurator.bsky.social
#nokingsday is even being covered by Fox... #nokings
Screenshot from Fox 9 Minneapolis/St Paul with the headline "No Kings protest: List of Minnesota rallies." Bullet points follow: "Dozens of No Kings protests are planned across Minnesota on Saturday," "The largest event is planned for the Minnesota State Capitol in St. Paul, where Gov. Tim Walz is expected o speak," and "Nearly 2,000 protests are planned in cities across the United States on Saturday, which is the same day as President Donald Trump's birthday."
June 14, 2025 at 3:34 PM
astrocurator.bsky.social
Built like a brick shithouse.
A brick shithouse on a leafy green lawn with an early 19th Century mansion in the background
May 17, 2025 at 7:03 PM
astrocurator.bsky.social
And thus shall we recognize traitors
Empty statue pedestal with inscription below "The parting of General Lee and Stonewall Jackson on the eve of Chancellorsville" and on the pedestal, "... is my confidence in General Lee that I am willing to follow him..."
May 17, 2025 at 6:58 PM
astrocurator.bsky.social
My timeline:
Two bluesky posts in a row: First, from Jane of the North: "My daughter canceled her work trip to New York and somehow this makes me incredibly sad. We don't want to boycott America, but it doesn't feel safe anymore." Second from The New York Times: "A 90-second failure of Newark Airport’s air-traffic safety systems, which blacked out communication to planes carrying thousands of passengers, has exposed a new level of crisis in U.S. air travel."
May 8, 2025 at 2:34 PM
astrocurator.bsky.social
The latest college rankings (seen at a bus stop shelter on Broadway at about 106th St in Manhattan)
Bus shelter advertisement with the typical US News and World Reports Best Colleges logo... For campus crackdowns, with a repeating motif of ICE agents holding billy clubs
May 8, 2025 at 1:40 AM
astrocurator.bsky.social
I and a few other people came out to suggest that the current administration might not be making the best choices in policy and personnel.
View of an enormous crowd at the base of the Washington Monument with a row of flags around the base View of the Washington Monument in the distance with a continuous crow between the camera and the monument
April 5, 2025 at 9:59 PM
astrocurator.bsky.social
In the last decade, 3 fish species have been discovered living deep in soil, not in water. They likely breathe through their skin rather than gills. Most recent was described by @mstiassny.bsky.social and team. The slide is from her (final) post-tenure review talk at @natural-history.bsky.social
Picture of three fish that resemble earthworms found in Costa Rica in 2024, India in 2018, and Cameroon in 2016. The most recent is named Ophisternon berlini.
April 4, 2025 at 3:57 PM
astrocurator.bsky.social
The CUNY MS in Astrophysics includes research opportunities in my group and others at AMNH @natural-history.bsky.social as well as at the @flatironinstitute.org Center for Computational Astrophysics. Please alert students to the opportunity.
Poster on nebular background: M.S. in ASTROPHYSICS NOW ACCEPTING APPLICATIONS FOR THE 2025 FALL SEMESTER! Apply at https://www.gc.cuny.edu/astrsophysics/admissions-and-aid Application deadline: April 15, 2025 Questions? Email astrophysics@gc.cuny.edu CUNY GRADUATE CENTER (logos)
April 2, 2025 at 4:21 PM
astrocurator.bsky.social
right next to you :-)
Man with hat in crowd holding sign saying: F = ma G_mu nu = 8 pi T_mu nu Science protects me and YOU
March 8, 2025 at 1:36 AM
astrocurator.bsky.social
MS students from this program are pursuing research projects in planet formation and binary black hole dynamics in my group. Register for the open house at htts://tinyurl.com/AstroOpenHouse25 🔭☄️
Poster for MS in Astrophysics Open House at the CUNY graduate center. March 20, 2025, 4-5 PM EST. Register at htts://tinyurl.com/AstroOpenHouse25. Questions to astrophysics@gc.cuny.edu. Department representatives will discuss: program description, degree requirements, application procedure, financial support.
March 4, 2025 at 3:35 PM
astrocurator.bsky.social
I curated the update of the visuals of the Hayden Planetarium Space Show "Passport to the Universe" @natural-history.bsky.social. I'm happy to say that this will be opening at the Planetarium on 16 Feb, after a closure to install a brand new sound system. www.amnh.org/exhibitions/...
Image of a galaxy from the Hayden Planetarium Space Show
February 12, 2025 at 4:44 PM
astrocurator.bsky.social
Funding has been released with the following email implementing this TRO nsf-gov-resources.nsf.gov/files/TRO-NY...
email reading: MESSAGE to the NSF PI Community, On Friday, January 31, 2025, a Federal Court issued a Temporary Restraining Order (TRO) directing Federal grant-making agencies, including the National Science Foundation (NSF), to “...not pause, freeze, impede, block, cancel, or terminate... awards and obligations to provide federal financial assistance to the States, and... not impede the States’ access to such awards and obligations, except on the basis of the applicable authorizing statutes, regulations, and terms.” Although the language of the TRO is directed at State institutions, the Department of Justice has determined that it applies to all NSF award recipients. You can review the TRO here. In order to comply with the TRO, the NSF Award Cash Management Service (ACM$) system is available for awardees to request payments as of 12:00pm EST, February 2, 2025. This message is also available on the Executive Order Implementation webpage. Please check back regularly as we add frequently asked questions (FAQs) based on community feedback. Sethuraman Panchanathan Director
February 3, 2025 at 12:22 AM
astrocurator.bsky.social
I'm happy to say that the NSF just restarted payments to NSF-funded postdocs (and all other grantees) following the temporary restraining order granted to the 22 states that sued.
email reading: MESSAGE to the NSF PI Community, On Friday, January 31, 2025, a Federal Court issued a Temporary Restraining Order (TRO) directing Federal grant-making agencies, including the National Science Foundation (NSF), to “...not pause, freeze, impede, block, cancel, or terminate... awards and obligations to provide federal financial assistance to the States, and... not impede the States’ access to such awards and obligations, except on the basis of the applicable authorizing statutes, regulations, and terms.” Although the language of the TRO is directed at State institutions, the Department of Justice has determined that it applies to all NSF award recipients. You can review the TRO here. In order to comply with the TRO, the NSF Award Cash Management Service (ACM$) system is available for awardees to request payments as of 12:00pm EST, February 2, 2025. This message is also available on the Executive Order Implementation webpage. Please check back regularly as we add frequently asked questions (FAQs) based on community feedback. Sethuraman Panchanathan Director
February 3, 2025 at 12:19 AM
astrocurator.bsky.social
Turning on Pro (using DeepSeek R1) gives an even more differentiated answer...
Screenshot of perplexity.ai pro answer to the question of what the core temperature of an O star is: O-type stars, known for their extreme temperatures and luminosity, have core temperatures that vary significantly depending on their evolutionary stage. During their main-sequence phase, these massive stars primarily fuse hydrogen via the CNO cycle, which requires core temperatures much higher than the Sun’s proton-proton chain. While the Sun’s core is ~15.7 million K2, O-type stars’ cores are estimated to reach tens of millions of Kelvin due to their greater mass and energy output24. In later evolutionary stages, such as Wolf-Rayet phases (evolved O-type stars), core temperatures escalate dramatically. For example, WR 102, a carbon/neon-burning Wolf-Rayet star, has a modeled core temperature around 1 billion K (10⁹ K)4. If such stars progress to oxygen or silicon burning, temperatures could briefly reach 2–4 billion K, though these phases last only years or days4. Key points: Main-sequence O stars: Core temperatures exceed 15 million K (exact values depend on mass and luminosity)23. Post-main sequence: Core temperatures rise to ~1 billion K during advanced fusion stages (e.g., carbon/neon burning)4. Short-lived phases: Silicon/oxygen burning might push temperatures to ~4 billion K, but these stages are extremely brief4. Thus, while precise measurements are challenging, theoretical models indicate O-type stars’ cores range from tens of millions to billions of Kelvin, depending on their mass and evolutionary state24.
February 1, 2025 at 4:15 PM
astrocurator.bsky.social
to be fair, perplexity.ai did rather better with this question, including citing at least half-decent sources:
Screenshot of Perplexity.ai answering the question: "What is the core temperature of an O star?" and showing its sources The core temperature of an O-type star is significantly higher than its surface temperature. While the surface temperature of O-type stars typically ranges from 30,000 to 52,000 K23, their core temperatures are much more extreme. The core temperature of an O-type star is estimated to be around 10 9 10 9 K (1 billion Kelvin)1. This incredibly high temperature is necessary for the fusion of heavy elements like carbon or neon, which occurs in the cores of these massive stars1. It's important to note that: Core temperatures can vary depending on the star's exact mass and evolutionary stage. The most massive O-type stars may have even higher core temperatures, potentially reaching 2-4 times higher ( 2 − 4 × 10 9 2−4×10 9 K) if they are in the final stages of their lives, burning oxygen or silicon1. These extreme core temperatures make O-type stars among the hottest known objects in the universe, driving their immense luminosity and influencing their relatively short lifespans. Related How do core temperatures of O stars compare to those of other star types What factors influence the core temperature of an O star Are there any known O stars with particularly high core temperatures How does the mass of an O star affect its core temperature What is the lifespan of an O star before its core collapses 8 sources
February 1, 2025 at 4:15 PM
astrocurator.bsky.social
still broken at 13:30 EST 17 Jan:
screenshot showing that a Google search on the phrase "Will water freeze at 27 degrees" provides a Search Labs AI Overview starting "No, water will not freeze at 27 degrees (presumably Fahrenheit) because..."
January 17, 2025 at 6:32 PM
astrocurator.bsky.social
Spectra of the oldest (furthest) galaxies currently known, at a redshift of 14, only 300 Myr after the Big Bang, likely close to the beginning of star formation in the universe.
Images at different wavelengths and spectra of two galaxies
December 6, 2024 at 4:21 PM