Episode 108 - He found a Green Star!

If you'd like to watch the video version of this interview, check it out here. 

EPISODE 108: GREEN STARS & SUPERNOVA SURVIVORS WITH DR. MARK HOLLANDS

What color would a white dwarf look if you could see it up close? That simple question led Dr. Mark Hollands to some surprising answers, including a star that would appear pale green.

This week, Roo welcomes Mark, a Warwick Prize Fellow and astrophysicist at the University of Warwick, for a conversation about the dense stellar remnants that most stars will eventually become. We explore why these stars can have unusual colors, how their spectra reveal their chemistry, and what those findings mean for the way astrophotographers think about star color.

Mark takes us through the Sloan Digital Sky Survey, Gaia's transformation of white-dwarf research, and the care needed when translating astronomical measurements into RGB colors. We also discuss the realities of working at professional observatories - from liquid-nitrogen-cooled cameras to telescope breakdowns and whether backyard imagers can photograph the stars in his study.

Then we turn to an extraordinary class of survivors: white dwarfs flung through space when their companions explode. Their chemistry offers clues to supernovae and the origins of elements around us. Mark also introduces his favorite stellar oddball, GD 492, known as LP 40-365.

There's room for the person behind the research, too: mushroom foraging, birding, sim racing, following your curiosity, and a Pink Floyd reference hiding in a scientific paper.

Also in this episode: an update on The Astrocast's new Move Shoot Move partnership!

IN THIS EPISODE
- How white dwarfs form and why they fascinate Mark.
- Pale-green, yellow, and pink stars...and why green is especially unusual.
- Spectroscopy as a chemical barcode for starlight.
- Gaia, PixInsight, and the limits of mapping measurements to visible color.
- Carbon molecules, dense atmospheres, and salmon-pink starlight.
- Professional observing, remote telescopes, and future surveys.
- Type Ia supernovae, runaway D6 survivors, and stellar chemistry.
- Practical advice for students interested in astrophysics.

CHAPTERS
00:00 Welcome to The Astrocast
01:24 Meet Dr. Mark Hollands: what is a white dwarf?
02:17 Mark's path into astronomy
05:09 The fate awaiting most stars
06:54 What colors are white dwarfs?
08:36 A star that would look pale green
09:32 How rare are unusual stellar colors?
11:50 Spectroscopy and a star's chemical barcode
16:07 Mining the Sloan Digital Sky Survey
18:35 How Gaia transformed white-dwarf research
21:26 Gaia, PixInsight, and star-color calibration
23:19 Red stars, carbon, and a salmon-pink white dwarf
28:16 Mushroom foraging, birding, and curiosity
31:56 Advice for aspiring astrophysicists
34:00 Life at a professional observatory
39:54 Book recommendation & Move Shoot Move update
40:47 Pink Floyd and Any Colour You Like
41:43 Can amateurs photograph these stars?
43:54 The next generation of spectroscopic surveys
45:57 D6 survivors: white dwarfs launched by supernovae
51:38 Supernova chemistry and the iron around us
54:21 Mark's favorite object: GD 492 / LP 40-365
56:39 Mushrooms, sim racing, and hobbies
57:59 A dream observation with the Extremely Large Telescope
59:37 Roo's closing thoughts
1:00:06 The Astrocast outro song

GUEST & RESOURCES
Dr. Mark Hollands:
https://mahollands.github.io/

Paper discussed: Any Colour You Like
https://academic.oup.com/rasti/article/doi/10.1093/rasti/rzag069/8914458?searchresult=1

Book mentioned: The Last Stargazers by Emily Levesque
https://link.amazon/B0eV2rQKv

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