David Trevascus

Keplerian motion of a compact source orbiting the inner disk of PDS 70: A third protoplanet in a resonance with b and c? The disk around PDS 70 hosts two directly imaged protoplanets in a gap. Previous VLT/SPHERE and recent James Webb Space Telescope/NIRCam observations have hinted at the presence of a third compact sou...

A big thanks to Iain Hammond, who provided us with his new astrometry for PDS 70 d! You can find his paper about new detections of the planet candidate here: arxiv.org/abs/2504.11127

17.04.2025 15:41 — 👍 1    🔁 0    💬 0    📌 0

By comparing our new mass constraints to luminosity evolution models from Spiegel & Burrows (2012) we determined that PDS 70 b and c are both hot/warm-start planets!

17.04.2025 15:41 — 👍 0    🔁 0    💬 1    📌 0

Two sets of orbits for the PDS 70 planets, with astrometry plotted over the top of each.

In order to tell hot/cold-start you need planet masses, and a good way to get those is through orbit fitting. We do a lot of different orbit fits, some of which include the new planet candidate PDS 70 d!

17.04.2025 15:41 — 👍 0    🔁 0    💬 1    📌 0

The differences between cold/hot-start planet formation are really important when we're searching for planets via direct imaging. Beta Pic b & c are hot-start, and so are the HR 8799 planets, but what about PDS 70 b & c?

17.04.2025 15:41 — 👍 0    🔁 0    💬 1    📌 0

Differentiating Formation Models with New Dynamical Masses for the PDS 70 Protoplanets Hot- and cold-start planet formation models predict differing luminosities for the young, bright planets that direct imaging surveys are most sensitive to. However, precise mass estimates are required...

My first PhD paper about hot/cold-start for the PDS 70 planets is now up on arXiv! You can find it here: arxiv.org/abs/2504.11210
Big thanks to all my co-authors and everyone else who helped push it over the line!

17.04.2025 15:28 — 👍 4    🔁 1    💬 1    📌 0

Planetary albedo is limited by the above-cloud atmosphere: Implications for sub-Neptune climate Energy limits that delineate the `habitable zone' for exoplanets depend on a given exoplanet's net planetary albedo (or `Bond albedo'). We here demonstrate that the planetary albedo of an observed exo...

I feel like people are overlooking the results of this paper which also came out today: arxiv.org/abs/2504.12030
tl;dr the amount of starlight being reflected into space by this planet is way too low to prevent a runaway greenhouse effect, which would not allow the existence of a liquid water ocean

17.04.2025 14:42 — 👍 4    🔁 0    💬 0    📌 0

INTRODUCTION

A very good online lesson-style thing about what ChatGPT is and whether it's a huge invention (or just bullshit).

Probably a great thing to get in front of your students, seeing as they're almost definitely using it regularly: thebullshitmachines.com

03.03.2025 10:05 — 👍 43    🔁 11    💬 4    📌 1

World's darkest and clearest skies at risk from industrial megaproject On December 24th, AES Andes, a subsidiary of the US power company AES Corporation, submitted a project for a massive industrial complex for environmental impact assessment. This complex threatens the pristine skies above ESO’s Paranal Observatory in Chile’s Atacama Desert, the darkest and clearest of any astronomical observatory in the world [1]. The industrial megaproject is planned to be located just 5 to 11 kilometres from telescopes at Paranal, which would cause irreparable damage to astronomical observations, in particular due to light pollution emitted throughout the project’s operational life. Relocating the complex would save one of Earth's last truly pristine dark skies.

The best dark sky in the world - the Atacama Desert in Chile, which hosts many @eso.org telescopes - is under threat from an industrial project. 🔭

Astronomers can sign a petition in favour of moving the planned industrial project: docs.google.com/forms/d/e/1F...

17.02.2025 08:46 — 👍 234    🔁 115    💬 5    📌 15

World's darkest and clearest skies at risk from industrial megaproject On December 24th, AES Andes, a subsidiary of the US power company AES Corporation, submitted a project for a massive industrial complex for environmental impact assessment. This complex threatens the pristine skies above ESO’s Paranal Observatory in Chile’s Atacama Desert, the darkest and clearest of any astronomical observatory in the world [1]. The industrial megaproject is planned to be located just 5 to 11 kilometres from telescopes at Paranal, which would cause irreparable damage to astronomical observations, in particular due to light pollution emitted throughout the project’s operational life. Relocating the complex would save one of Earth's last truly pristine dark skies.

The skies above Paranal are at risk from a proposed industrial megaproject. 

This would be located in the vicinity of ESO's Observatory. If constructed, it would irreparably impact astronomical observations.

Read more: https://www.eso.org/public/news/eso2501/
🔭 

📷 ESO/P. Horálek

10.01.2025 08:00 — 👍 244    🔁 186    💬 6    📌 28