A Christmas Eve Astrobite

I've put up a final post on Astrobites this year, on Christmas Eve, of all days! Especially after posting one on Thanksgiving. This is actually the post I wanted to write for Thanksgiving, but time constraints and the fact I already had one half-written changed that.

This paper is about how our Sun is so incredibly stable in brightness over time compared to other stars. In fact, its variability is so much lower than other stars that it's been a long-standing puzzle in solar physics. To explain it briefly, the authors of the paper I wrote about did some simulations of Sun-like stars while varying a few key parameters such as the proportion of elements besides hydrogen and helium and the star's effective temperature. What they found is that the Sun sits in a very special place in phase-space where it ends up being almost perfectly constant in brightness over the course of its solar magnetic cycle. Changing the metallicity or temperature by extremely small amounts (relatively speaking)—in any direction—causes the variability over a star's magnetic cycle to shoot up dramatically.

(The mechanism I thought was pretty interesting: magnetic activity in stars causes two types of phenomena, starspots which are darker than average, and faculae which are brighter than average. Most stars are dominated by one or the other over the course of a magnetic cycle which changes their brightness, but the Sun's parameters cause the relative numbers of sunspots and faculae to almost perfectly balance in such a way that its average power output as seen from Earth is almost constant.)

This is actually final astrobite as a scheduled author; going into my second year of my PhD I've decided to retire from the active rotation to be able to focus more on my research. However, I'm not done writing just yet! I'll be able to write posts for the queue, and I still intend to, which just means I won't know when they'll go out. I no longer need to write one every month or so, so the number may go up or down depending on how many interesting papers I come across. Honestly, that's the part I'm looking forward to the most: some of my posts were on papers I found genuinely fascinating and loved explaining and I'm really proud of them, while a few of them were written just because I had a deadline and were the most interesting least boring papers I could find recently. Being able to write only when I'm really motivated (kinda like I do here…) is quite an exciting prospect!

I feel like that may have ended up more melancholy than I intended, so how about some Christmas presents? For the featured image for my posts I used the painting below, which I painted last Thursday as a present for my adviser:

“A Solar Twin,” by me.

(Unfortunately I miscalculated when he was going on vacation so he'll find it when he gets back in January, I guess. Some of my friends were ribbing me that I'm setting unrealistically high expectations for the other students now!)

Painting a star turned out to be so much fun that I painted another one the next night, a pulsar for my associate adviser:

“A Pulsar,” also by me.

Ignore the ugly shadow cast by my easel at the top of the picture. Which, I realized, I haven't mentioned yet, so yes, I bought an easel! I feel like a real artist now. An easel makes painting so much easier. I picked one that's quite portable and folds up nicely so I can bring it home (as I've done over the break, along with my painting supplies). It's sitting in the corner with my current work on it, and I must say, an easel with a painting in progress on it really classes up the room it's in!

Anyway, that's enough for tonight. Merry Christmas everyone, and I hope to be back with some more posts soon now that I'm on vacation.