A couple of quick notes from Dr. Pamela
This post is going to look really different. We’re changing how we doing things a little bit in hopes that we can bring you more content a bit more easily. Please give us feedback! Does this work? What can we improve?
This episode includes an interview with composer David Joseph Wesley. We put extra effort into editing so we could get the music inserted as best we code. The extra effort combined means this is coming to you later than we would have wished.
Media
- Listen on Libsyn
- Watch on Twitch (we’re still working on the final video)
Transcript
It. Is. Friday. To celebrate, we are going to be joined by special guest Composer David Joseph Wesley. He is the composer of the Astronomy Cast theme song, and some of my favorite music to play without lyrics, including Music to Smuggle By. As a fan of science and science fiction, Dave’s work is often influenced by human and robotic space exploration, and today we’re going to be talking about his album tribute to the Cassini Mission. But before we do that, let’s take a quick run through the news.
Our first story comes to us from Cornell and makes what feels like outrageous claims about how astronomers can search for life in our universe. A new paper in the Astrophysical Journal Letters, by scientists Thea Kozakis, Zifan Lin, & Lisa Kaltenegger, claims that we can determine if a world orbiting a white dwarf star has life, based on how it looks in that dead star’s light. They believe that this kind of work can be done by near future telescopes, like the Extremely Large Telescope being built in Chile.
Now, we don’t often take apart papers on this channel; we leave that for folks like Ethan over on Starts with a Bang. Instead, we try and only cover stories with the most solid science and highlight caveats as needed. The thing is, this is such a tangle of awesome and likely impossible that I want to take a moment to critique things.
Let’s start off by considering white dwarfs. These compact objects are the remaindered cores of stars like our sun that have puffed off their outer atmosphere at the end of their lives, leaving behind a hot core that is no longer undergoing nuclear reactions but is still glowing from the left overheat of its past activity. The atmospheres of these objects are dominated by hydrogen and helium, and they are so hot that they have either no or very few spectral lines. This means they are essential hot little lightbulbs of continuum radiation, emitting a mostly smooth rainbow of light. This is an ideal source to use for backlighting a planet’s atmosphere and trying to measure the composition of that planet’s atmosphere. Now, being an ideal light source isn’t enough. For this research to fly, you also need to find planets around white dwarfs, and so far, we haven’t found anything that resembles a planet as we know it orbiting a compact object.
And this is where the evolution of stars makes this a cool piece of research that may not have future applications. As stars age, they bloat up and eat anything in their inner solar system. They give off massive stellar winds, broiling what planets are left with light and particle streams. Any world that is left… is going to be in a bad way.
But this team has modeled how healthy worlds teeming with life could be found.
Now, I’m not going to say this just isn’t possible. Our universe is large and given enough tosses of the dice, anything could happen. For instance, a world cast off from its host star in a 3-body interaction could get gravitationally grabbed by the white dwarf, and allowed to warm and form life under the white dwarf’s UV-rich glow. This paper describes the habitable zone around a white dwarf, and if you have enough atmosphere, sure… go for it. While I’m not going to say anything is possible – going faster than the speed of light is not possible. That said, some things are more and less probable and this just isn’t probable … but if it happened, this paper describes how to find life in these improbable systems. I appreciate that folks are now saying – Anywhere could support life. I just want more context in my press releases I guess.
In trying to figure out where life may and may not exist in the universe, we often use our own solar system as a starting point. Early on in our explorations, we started from the assumption that our Sun is more or less average. Sure, there are stars that are metal-poor and live in different parts of our galaxy, but we thought that for metal-rich stars in the disk, we were fairly normal. No, audience, we’re not. We’ve got all the metals (and by metals, I mean elements heavier than Helium). We used to think our star is of average activity levels, blasting or not blasting its world in average ways. Now, in a new paper from Science, we’re seeing that our Sun is actually unusually sedate. Research led by Timo Reinhold, of the Max Planck Institute for Solar System Research, looked at 369 Sun-like stars and found that our Sun’s activity is remarkably calm compared to stars of similar age, content, rotation rate, and other physical properties. These stars were observed by Kepler from 2009 – 2013. This is a long enough baseline and enough stars that we’d expect to catch stars in a wide range of their activity cycles, assuming they are like the Sun, and vary in activity over time.
CREDIT: MPS / hormesdesign.de
With our Sun, the irradiance varied by about 0.07 percent across its active and inactive phases. Other stars typically varied more like 0.3 percent, which still isn’t a lot, but is 5 times more than what we see. It’s unclear if this is a fundamental difference with our Sun, or if the 9000 years of solar understanding we can glean through the geologic record is representative only of a 9000-year calm that precedes a future storm. It could be that in the future things go entirely sideways as our Sun decides to throw temper tantrums in its old age. This not knowing is a bit disconcerting. It’s not like I’ll be around for future flare-ups, but I’d still like to think our Sun is just calm. But.. the universe doesn’t care what I think, and for now, I’m just going to hope future research allows us to understand why our Sun appears so calm today.
Learn More
Looking for life in White Dwarf Orbits
- Cornell Press Release
- “High-Resolution Spectra and Biosignatures of Earth-like Planets Transiting White Dwarfs,” Thea Kozakis, Zifan Lin & Lisa Kaltenegger, 2020 April 30, Astrophysical Journal Letters, Free access on arXiv
Our Sedate Sun
- Max Plank Institute for Solar System Research Press Release
- “The Sun Is Less Active Than Other Solar-like Stars,” Timo Reinhold et al., 2020 May 1, Science
David Joseph Wesley
- Social Media: @DJWfilmmusic, Facebook
- Primary Website: www.djwfilmmusic.com/
- Get music on: Bandcamp, Spotify
Credits
Written and produced by Pamela Gay
Intro and Outro music by Kevin MacLeod, https://incompetech.com/music/
This episode contains additional music by David Joseph Wesley
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