#adventoftess — Public Fediverse posts

Very cute tessellation today, less complex than yesterday's but with even more twists (36 of them!), called Pebbles. Quite pleasing to fold, now that I am starting to get used to the techniques involved. It's the same on both sides! And I like the laces on the backlighting view

9/25

#AdventOfTess #tessellation #origami

Oof... This is the most difficult tessellation that I ever folded. It's called Maelstrom and tightly weaves twists from both sides of the paper to create a dense storm. I'm a fan!

8/25

#AdventOfTess #tessellation #origami

I loved this one (Citrus Slices)! Quick and easy, and introducing closed rhombus twists. The backside is really pretty too! I think it's one of the patterns that I will redo on larger paper at some point :)

7/25

#AdventOfTess #tessellation #origami

I find this one very pretty and I am not sure if black was the best color for it... The range of twists still expands with this one, which uses a central double hexagon twist, six simple hexagon twists on the reverse side, and simple triangle twists on the front. I think the pattern works particularly well!

6/25

#AdventOfTess #tessellation #origami

Again a nice model today, called Hexagon Double Bar Wells. It has hexagon twists in one side and open triangle twists on the other side. I lacked a little bit of precision for the hexagon twists, as can be seen by the size of the dots inside them on the backlighting view... The close placement of these patterns created some tricky interactions. I can feel the difficulty ramp up already! 😅

5/25

#AdventOfTess #tessellation #origami

Woo I really liked today's tessellation, called Wobbly Pyramids! It looks the same on both sides (it's actually mirrored). To achieve this, one has to fold twists on both sides of the paper: it was my first time doing that. It comes with a new kind of challenge: making sure that the paper that you need on one side is not stuck on the other side, and it requires a bit of planning. That was fun! And I really like the backlighting of this one :)

4/25

#AdventOfTess #tessellation #origami

Third day, although it looks a bit similar to yesterday's, today's tessellation introduces double open triangle twists, and includes all three sizes with its pattern. It required a bit of precision in the twists because many triangles ate touching. The name of this one is Gravity Wells.

3/25

#AdventOfTess #tessellation #origami

The #AdventOfTESS has beaten me. I've run out of time to catch up for the weekend or fill in tomorrow. I can only leave you with the amplitude spectrum of δ Sct variable EW Cnc, aka WOCS 4006, a blue straggler in M67.

Vernikar et al. (2023) studied this an several other such stars and, among other things, show using Kepler data that the peak around 5.5 cycles per day is a contaminant (itself a δ Sct variable?).

https://ui.adsabs.harvard.edu/abs/2023MNRAS.524.1360V

Sorry I won't have time for more but Merry Christmas! 🎄

Today the #AdventOfTESS offers our first (a bit surprisingly) RS CVn variable, DR Dra. There's stacks of data: it's been visible in 36 sectors and there's at least 23 sectors of 120-second data. Here I first shown the light curve, where we see the spots evolving on the K0 dwarf, which has a white dwarf orbiting it.

You might notice a few flares, which are not unusual in these systems but try the second light curve! 💥

I've bent the rules of the #AdventOfTESS to pick the RR Lyrae variable WY Dra. To mix it up a bit, here's a sort of phase fold on slightly under 5× the pulsation period (0.589d) to show just how much data there is. This is TESS sectors 52–54, so about ~81d of data, or about 150 pulsation periods, all recorded at 2-minute cadence. 🤩 There's ~18 sectors across all cadences.

Relative brightness changes are reasonable; the absolute scale is a nonsense artefact of my phase fold offset.

#astronomy

It's another truly interesting eclipsing binary in the #AdventOfTESS!

TESS has observed CK Dra during 8 sectors spread over more than 4½ years. The segment of the continuous light curve shows the eclipses superimposed on background variation that I think is misaligned tidal distortion. Better still, the second plot are the first and last complete orbits in the data, showing how the non-eclipsing variations have changed over those ~4½ years.

#astronomy

You sigh at another eclipsing binary in the #AdventOfTESS but at least this one comes with a twist. U Col looks is in many ways a typical eclipsing binary ...

... but it's also a pulsating star, with one of the stars being a δ Sct variable. You can see the basic idea in the amplitude spectrum (up to ~25 c/d is orbital harmonics; ~40-65 c/d is pulsations) but there's a more detailed analysis in Chen et al. (2022). Look for TIC 124688144 in the arXiv version:

https://arxiv.org/abs/2211.05283

The #AdventOfTESS marches on! Today it's AD Boo, which might draw a yawn because it's yet another eclipsing binary, but it's also a double-lined spectroscopic binary. The absolute masses and radii can be derived precisely enough for it to feature on John Southworth's list of detached, well-characterised binaries.

https://www.astro.keele.ac.uk/jkt/debcat/

The phase-folded light curve is another textbook example.

Since it's a Saturday in the #AdventOfTESS, I'm taking a bit of time to skip ahead to a very interesting object on the list: EI Psc. If I've understood the catalogues correctly, this is a cataclysmic variable—a class of accreting white dwarfs (WDs) that occasionally brighten for various reasons. Here, the WD's accretion disk suddenly becomes optically thick and much brighter. The accretion rate then rises and drains the extra material from the disk, so that it goes back to being optically thin.

Are we halfway through the #AdventOfTESS? I sort of hope so: it's quite hard keeping this up!

Today we've got VZ Psc, an tiny contact binary (~6h orbital period) that probably comprises two red dwarfs. This was observed in TESS's super short cadence (20s!) mode, surprisingly as part of a proposal to observe solar-like oscillations (GO Program 6191, PI: Ashley Chontos). Not sure we were ever going to see oscillations but glad they observed it anyway!

It's another eclipsing binary, MV CMa, in the #AdventOfTESS today. I picked this system next from my randomised base list because the eclipses are almost indistinguishable. Can you spot the difference between the primary and secondary eclipse? 🧐

I'm not sure if it's clearer in the light curve or the phase fold (both are amazing, the scatter is ~mmag! 🤩 ) but the secondary is about 5mmag shallower.

#astronomy

We've lucked it in the #AdventOfTESS with another pulsating star. Today we have EG Gru, a typical RR Lyr variable. As with many stars in the #AdventOfTESS, this data is reduced from the full-frame images (specifically MIT's Quick-Look Pipeline). This textbook RR Lyr variable was not specifically targeted!

Today the #AdventOfTESS returns to pulsating stars with XX Cyg, which is a textbook example of a SX Phe variable. The SX Phe variables are basically the "Population II" equivalents—older and poorer in metals—of δ Sct variables.

As an aside, I feel like I don't see the terms "Population I" or "II" much any more. #astronomy 🤔

Ugh, why another eclipsing binary in the #AdventOfTESS, you ask? Well, though it's a fairly unremarkable and little studied system, I picked out AZ CMa because it shows what TESS can do even when stars are impressively faint. This is near the limit of what TESS can see (Tmag~16) but it nevertheless gives a remarkably good phase-folded light curve.

There's so much in TESS's full-frame images! (Thanks to the TESS-Gaia Light Curve community data product for this one.)

https://archive.stsci.edu/hlsp/tglc

The #AdventOfTESS today returns to more standard fare with the detached eclipsing binary CP Gem. I want to note here that this is data reduced from the full-frame images (FFIs) taken every 10 min in the first extended mission (S43–45). That was down from 30 min in the nominal mission and reduced to 200s (!) in the second extension.

TESS wasn't even trying to observe this star!

#astronomy

Today's star in the #AdventOfTESS is the very bright and very red long-period variable HW Dra. Note that with variability like this, the mean magnitude shifts enough between each segment of TESS's observations that the pipeline data (grey) leaves clear jumps between segments. I've crudely tried to fix these up (blue) but regard this only as representative of this stars slow, but real, variations, common in very large red (super)giants.

(It's also very bright, which is a whole other problem.)

@warrickball I didn't know I needed this #adventOfTESS 🙌

I guess the #AdventOfTESS is mostly for me anyway so it's fitting that we've finally got a pulsating star. Specifically, it's the δ Sct variable LW Mus. The light curve is a classic but I've also shown the amplitude spectrum, where you can see multiple frequencies beyond the harmonics of the non-sinusoidal fundamental.

#astronomy

There's still time for today's star in the #AdventOfTESS, which is DY Ceti, a WUMa (contact) eclipsing binary (EB). It's another textbook example from TESS and probably not the last. EBs often vary quite a lot in magnitude, so their variability is relatively easy to detect and there are many among the stars with Argelander designations.

Three years ago, I ran an #AdventOfTESS on Twitter, where I posted a light curve of a random variable star, as observed by NASA's TESS observatory. Against my better senses and despite being a day late, I'm going to try to do the same thing again.

The stars are a partially random selection with Bayer or Argelander designations, plus a bit of curation to keep it exciting. But I haven't the time to screen or analyse too much, so I'm mostly just throwing them out there. Here goes!

#astronomy