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#Astrodon

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On Dust Devil Diameters, Occurrence Rates, and Activity

"Where a typical terrestrial dust devil might span several to ten meters in diameter and hundreds of meters in height, Martian dust devil could be hundreds of meters across and kilometers tall."

by Brian Jackson and co-authors
arxiv.org/abs/2507.03643

arXiv logo
arXiv.orgOn Dust Devil Diameters, Occurrence Rates, and ActivityAs a phenomenon that occurs on Earth and on Mars, the diameter of a dust devil helps determine the amount of dust the devil injects into the atmosphere for both worlds -- for a given dust flux density (dust lifted per area per time), a wider devil will lift more dust into the air. However, the factors that determine a dust devil's diameter $D$ and how it might relate to ambient conditions have remained unclear. Moreover, estimating the contribution to an atmospheric dust budget from a population of dust devils with a range of diameters requires an accurate assessment of the differential diameter distribution, but considerable work has yet to reveal the best representation or explain its physical basis. In this study, we propose that this distribution follows a power-law $\propto D^{-5/3}$ and provide a simple physical explanation for why the distribution takes this form. By fitting diameter distributions of martian dust devil diameters reported in several studies, we show that the data from several studies support this proposed form. Using a previous model that treats dust devils as thermodynamic heat engines, we also show that the areal density of dust devils (number per unit area) $N_0$ scales with the product of their thermodynamic efficiency $η$ and the sensible heat flux $F_{\rm s}$ as $N_0 \propto ηF_{\rm s}$.

VLT timelapse of 3I/ATLAS, a new interstellar object

In this video, 3I/ATLAS is seen moving to the right over the course of about 13 minutes. These data were obtained with the FORS2 instrument on the VLT on the night of 3 July 2025, just two days after the comet was first discovered. At the end of the video, we see all frames stacked into a single image: the deepest and best to date we have of this foreign object.

eso.org/public/videos/potw2527

#paperday (submitted to A&A) on #astroph:

"On the interpretation of XRISM X-ray measurements of turbulence in the intracluster medium: a comparison with cosmological simulations" by myself and G. Brunetti.

arxiv.org/abs/2507.04727

It's short reaction paper to the latest (cool) XRISM measurements of gas motions in the Coma cluster (and others), which were interpreted as evidence of weak and much-steeper-than-Kolomogorov turbulence.
We think this is wrong..
#science #astrodon #astronomy

Heads-up: we have images of a new interstellar visitor! ☄️ 👀

Comet #3IATLAS is only the third object ever spotted coming from beyond our Solar System.

In this timelapse, our Very Large Telescope in #Chile observes the comet move across the night sky — just two days after its discovery!

youtube.com/watch?v=IXJ221XXPvM

Call for Expression of Interest to become a member of the European Space Agency Science Advisory Structure:

▶️ cosmos.esa.int/web/expression-

Through the present Call, the #ESA Director of Science invites scientists affiliated with institutions in the ESA Member States to express their interest in being a member of the Space Science Advisory Committee (SSAC), Astronomy Working Group (AWG), or the Solar System and Exploration Working Group (SSEWG).

Expression of interest for Science Advisory membersHome - Expression of interest for Science Advisory members - Cosmos

🇬🇧 Monday at 16:30, the PhD ceremony of Zheng Cao will start at Radboud University. He did research on medium sized black holes. Good luck, Zheng!

🇳🇱 Op maandag om 16.30 start de promotieplechtigheid van Zheng Cao aan de Radboud Universiteit. Hij deed onderzoek naar middelgrote zwarte gaten. Zet'm op Zheng!

astronomie.nl/promoties/probin

cc:
@Radboud_uni

www.astronomie.nlProbing Intermediate-mass Black Holes Using Tidal Disruption Events (promotie Zheng Cao, RU)