Sihao Cheng

Our new paper just came out! More scientists are seeing the promise of finding real-world features with ML+XAI. We examine what scientists mean when they talk about features here, and how this can be useful/misleading. tandfonline.com/doi/full/10.10…

@dr_guangtou @RAS_Journals In overleaf, you may just type the Chinese characters in the line of authors, but then include the line of "\maketitle" inside the Chinese environment, like below: \begin{CJK}{UTF8}{gkai} \maketitle \end{CJK} instead of doing it for the line of explicit author names.

Does anyone know whether MNRAS @RAS_Journals supports author names in CJK characters like ApJ?

Have to say, the price of insulin in the U.S always triggers me...It feels like murder given how cheap it can be and how critical it is to a large population...

So @BBCNews did a short documentary about Covid-19 and Wuhan...In the opening scene, they put Wuhan like 1000 miles away from where it really is... That yellow spot is Wuhai, Inner Mongolia (乌海); not Wuhan (武汉) You may say negligence, I say arrogance

A boring footnote: our logic chain is: high velocity -> 22Ne -> C/O core -> merger, not directly high velocity -> merger, because the merger delay (less than the extra cooling delay) is not important on the Q branch (but important above the branch) 8/8

So, we have shown a cooling anomaly and proposed a possible explanation. Should we say that we understand or not understand the white dwarf cooling now? 7/8

Do we really understand the cooling of white dwarfs? Yes, and no. Thanks to Gaia DR2, an amazing feature called the "Q branch" on the HR diagram is revealed. We show that this huge branch is connected to an anomaly of white dwarf cooling: arxiv.org/abs/1905.12710 (updated) 1/8

@jotajotahermes @arxiv @crohnslifter @astrowizicist @kenjshen I agree with you. Moreover, according to Kilic et al. (2018) LP 93-21 has [C/He] ~ -3.5, similar to other DQ white dwarfs on the Q branch. So, maybe it is really a very old white dwarf having just finished its long stay on the Q branch.

@arxiv @crohnslifter @astrowizicist @SihaoCheng (3) Finally, so far all of the bound remnants claimed by Roberto Raddi, @kenjshen, et al. are extremely carbon deficient -- they are, on average, sub-solar in carbon! LP 93-21 is dominated by carbon. Granted, bound remnants should have lots of carbon, but it's a mismatch. 7/8

An intriguing paper was posted to @arxiv this week by @crohnslifter and @astrowizicist claiming to find the closest known star unbound to the Galaxy. It's a really cool result, star, and analysis, but the interpretation puzzles me. The paper is here: arxiv.org/abs/1908.00670 1/8

@astrocrash @jotajotahermes The energy release also depends on the density change between the two materials. The O sedi. replaces some C by O in the core, and 22Ne settling some C/O by 22Ne. I think for a given pressure, the density change of C->O replacement is tiny, but for C/O->22Ne, it is much larger.

For the past year I've been puzzling over why this line of high-tangential-velocity white dwarfs sticks out of the #GaiaDR2 CMD. The red lines are for roughly 0.6 and 1.2 Msun white dwarfs, and cooling tracks don't at all go down this line. I had a breakthrough last week...

@fisherastro @jotajotahermes It might be a bit boring but at least the DQs on the Q branch are not magnetic, different from the hot-DQs. I show the magnetic and non-magnetic DQs in figure 8 of the paper JJ mentioned (arxiv.org/abs/1905.12710). By the way I have a new webpage now pages.jh.edu/~scheng40/