Michael Perryman

Scientist/astronomer, writing weekly essays on the scientific results from ESA's space astrometry mission Gaia.

[Michael Perryman @mac_perryman]

My latest caving video of Swildon's, Mendip hills, Somerset, under 15.000 ANSI lumens of illumination
https://t.co/Tt5gONB87I

[Michael Perryman @mac_perryman]

From today, I'll no longer be using X to mention my new essays on Gaia science, which currently appear every two weeks. Instead, you can get email notifications by subscribing at https://t.co/rB1t9Bthmu

[Michael Perryman @mac_perryman]

Gaia essay 242. Oumuamua, Borisov and ATLAS. These 3 interstellar objects, travelling through our solar system, were ejected from the protoplanetary disks of planetary systems far from the Sun. I detail how Gaia is assisting in understanding their origin. https://t.co/tqGnGYR3N6

[Michael Perryman @mac_perryman]

Gaia essay 241. Asteroid masses. Asteroid masses are primarily determined from mutual orbit perturbations. I review the knowledge pre-Gaia, and show how Gaia is allowing improved mass estimates for many more of these solar system objects. https://t.co/lH7khhEuM7

[Michael Perryman @mac_perryman]

Gaia essay 240. Extreme nuclear transients. The recent discovery of the highest-known luminosity transient, in the Gaia science alerts, points to an extreme example of tidal disruption: of an intermediate-mass star onto a particularly massive black hole.
https://t.co/v8EytiNFI9

[Michael Perryman @mac_perryman]

Gaia essay 239. Actinide-boost stars. Actinide-boost stars display an over-abundance of the actinide elements, characterised by the [Th/Eu] ratio. DR3 is providing surprising insights into the mechanisms underlying the enhancement of the r-process elements https://t.co/Qh2uattFRU

[Michael Perryman @mac_perryman]

Gaia essay 238. Ophion: a most curious cluster. A new determination of astrophysical parameters has emphasised pre-main sequence stars. An analysis of the resulting sky distribution has identified a new young association in the process of rapid disruption.
https://t.co/pQkYnOC2QY

[Michael Perryman @mac_perryman]

Gaia essay 237. Beta Cephei variables. Beta Cephei variables are the most massive pulsating stars on the main sequence. The sparsely sampled Gaia photometry is proving highly accurate for detecting their dominant and secondary asteroseismic frequencies.
https://t.co/ylf1kNFoOy

[Michael Perryman @mac_perryman]

Gaia essay 236. More on interstellar extinction. Recent studies based on Gaia DR3 throw new light on the processes of accretion and coagulation that are responsible for the growth of dust grains in the interstellar medium.
https://t.co/wiGX3iSEqI

[Michael Perryman @mac_perryman]

Gaia essay 235. Populations in globular clusters. The occurrence of multiple stellar populations in globular clusters has been described as one of the most puzzling open issues of stellar astrophysics. I explain how Gaia is helping to identify its origin. https://t.co/pAXfr5Iqy7

[Michael Perryman @mac_perryman]

Gaia essay 234. Ultra-faint dwarf galaxies. Ultra-faint dwarfs represent the faintest, oldest, most metal-poor, and most dark-matter-dominated end of the dwarf galaxy spectrum. Gaia is refining their membership, their morphologies, and their orbits. https://t.co/GtDdZovsKw

[Michael Perryman @mac_perryman]

Gaia essay 233. Two more exoplanets: Gaia 4b and 5b. Today, NASA's Exoplanet Archive lists almost 6000 confirmed exoplanets. There are only five astrometric discoveries amongst them. Here I describe the two latest discoveries, Gaia 4b and Gaia 5b. https://t.co/kgXTBBuzb2

[Michael Perryman @mac_perryman]

Gaia essay 232. Delta Scuti stars. Delta Scuti variables lie at the intersection of the instability strip with the main sequence. Gaia data are being used to characterise their period-luminosity relation, and other aspects of their pulsation behaviour.
https://t.co/I20L8dVOIi

[Michael Perryman @mac_perryman]

Gaia essay 231. Dwarf spheroidals: an update. In the latest studies, Gaia DR3 is being used to derive improved orbits and orbital histories, with new studies of their structure, internal kinematics, bulk rotation, and of their associated globular clusters. https://t.co/snRHKIUCqg

[Michael Perryman @mac_perryman]

Gaia essays 229. RR Lyrae variables: an update
and 230. The Oosterhoff dichotomy
I'm off for two weeks, so here's an early link to my next two essays. If you're interested in galaxy formation, do read about Gaia's contribution to the Oosterhoff dichotomy https://t.co/Pn7SobWf9x

[Michael Perryman @mac_perryman]

I've converted my first 80 Gaia essays to an audio discussion format using generative AI. The results, which are accurate and engaging, are on my YouTube channel https://t.co/zo13W1stg8. Numbers 46 and 47, for example, describe the astrometric iterative solution. Have a listen!

[Michael Perryman @mac_perryman]

Gaia essay 228. Cepheid variables: an update. Based on the 15,000 classified Cepheids in DR3, advances include improved assignment to their membership of open clusters, updates of the period-luminosity relation, and various studies of Galactic structure.
https://t.co/fsbt1NJSTs

[Michael Perryman @mac_perryman]

Gaia essay 227. I am converting my written Gaia essays into audio format using the powerful technology of generative AI. The results, placed on my YouTube channel (https://t.co/rUWUpsch9n) are comprehensive, accurate, and engaging. Do have a listen! https://t.co/69u1Aln6rl

[Michael Perryman @mac_perryman]

Gaia essay 226. Heartbeat stars. A remarkable subset of the binary star ellipsoidal variables are the so-called heartbeat stars. I outline their discovery, the physics underlying the phenomenon, and the role that Gaia can play in their understanding. https://t.co/uBiZSv2vyj

[Michael Perryman @mac_perryman]

Gaia essay 225. Rotational parallaxes. Distances can be determined to Local Group disk galaxies using the `rotational parallax'. I describe the cosmological relevance, and the current status for M31 and M33.
https://t.co/vlpm3LSBcw