Denis Vida

H mag of 11? Wowza! I hope we get some albedo measurements.

UPDATE on our new interstellar friend #A11pl3Z:
Citizen scientist Sam Deen has found earlier observations of from June 25-28, from the ATLAS telescope!

Now with 6 days' worth of data, the eccentricity of A11pl3Z's trajectory is narrowed down to e=10.4 ± 1.1!
... that's undoubtedly interstellar.
🔭☄️

'It's like taking a picture of lightning': How astronomers raced to track the smallest asteroid ever seen "Without question, it was the most exciting hour of my job that I’ve ever had."

got interviewed about our paper on 2022 WJ1 by space dot com: www.space.com/the-universe...

Another handheld video from closer by!

The first videos of the #asteroid #C0WEPC5 entry in #Russia are coming out on @telegram. It appears to be very similar to previous asteroid entries (2022 WJ, 2023 CX1, 2024 BX1). Lots of fragments at the end, it probably dropped some rocks in a remote forested area.

for the first time, we were able to compare telescopic observations of an asteroid to later fireball camera observations of it as it burned up -- both techniques agree really well: *2022 WJ1 was the smallest asteroid ever characterized in space*. [woo-hoo!]

out today in the planetary science journal: "Telescope-to-Fireball Characterization of Earth Impactor 2022 WJ1" lead by yours truly. many thanks to my incredible coauthors, especially @meteordoc.bsky.social in the #2 spot, for making this study possible. iopscience.iop.org/article/10.3...

We plan to apply this approach to many more meteors from more showers, enabling us to remotely probe the composition of comets. We also plan to create a catalogue of models for each shower including full fragmentation, enabling the use of these advanced models in the community.

These findings are different from what Kikwaya et al. (2011) found (figure below), especially for objects on Jupiter-family orbits. They found very high densities of ~3500 kg/m3, which would make them solid silicates with no porosity, which does not match in situ ROSETTA findings

We find that meteoroids from Halley-type comets have bulk densities 200 - 500 kg/m3 (~90% porosity), and shower meteoroids from Jupiter-family comets are only slightly denser at 500-1000 kg/m3. The #Geminids are much denser, ~1400 kg/m3, pointing to carbonaceous composition.

The model assumes that cometary meteoroids are composed of small silicate grains and are fluffy, just like dust observed by
@ESA_Rosetta
and collected in the stratosphere with repurposed U2 spy planes.

We have carefully fit a meteor fragmentation model to 41 meteors from meteor showers with known parent bodies to learn about the composition of specific comets. The model accurately reproduces the wake, directly informing the structure of the meteoroid.

We use the Canadian Automated Meteor Observatory's mirror-tracking system to observe meteors in unprecedented detail, seeing details of fragmentation and wake for each meteor

A Physical Survey of Meteoroid Streams: Comparing Cometary Reservoirs In this work, we present an optical survey of mm-sized meteoroids using the Canadian Automated Meteor Observatory's (CAMO) mirror tracking system. The system tracks meteors to magnitude +7.5...

In our new paper on #arxiv, we measure the density and structural composition of mm-sized meteoroids and find that cometary dust arriving on Earth is fluffer than we thought! #astronomy #meteors
arxiv.org/abs/2312.00897

Here is a good first-person account by Ruth: www.theguardian.com/lifeandstyle...

"... she heard a large bang and then looked up to find a hole in her ceiling and a fist-sized rock on her bed. Hamilton advised the rock gave off a burnt metallic smell and appears it was the rock that created the hole down through her ceiling." 2021-10-03 at 23:50 MST

See our latest paper on the Golden #meteorite in #Canada which fell into a bed, inches away from the head of Ruth Hamilton who was asleep at the time: arxiv.org/abs/2310.17822

#astronomy

Today's space plot: distribution of orbital heights for cataloged objects currently in Low Earth Orbit, by object type (Starlink is offscale high here). X axis is height in km

a = 2.512 AU
e = 0.6295
i = 11.911 deg
peri = 215.044 deg
node = 189.219 deg

Another tiny ~30 g #meteorite ~100 km south of #Quebec City went into the dense woods near Lac Aylmer. Speed of 17 km/s, 66° entry angle. Observed between 85.4 - 28.7 km. Credit: Robert Veronneau, Michel Saint-Laurent, Guy Létourneau #globalmeteornetwork

A #fireball dropped a tiny ~20 g #meteorite some 100 km SW of #Perth, #Australia. It entered the atmosphere at a slow speed of 13.5 km/s, 60° entry angle. It was first observed at a height of 82.6 km and its terminal height was 30.7 km. Credit: Dave Rollinson #globalmeteornetwork