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Steven Silverberg @silverbergastro.bsky.social · 3h

Raised to believe he's arguably the Greatest American, tbh.

I mean, Abe Lincoln never skipped a World Series game for Yom Kippur now, did he.

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Steven Silverberg @silverbergastro.bsky.social · 19d

First vehicle for me was a '91 Previa that was as old as me and had belonged to my grandfather, who had a backup beeper installed after-market. Took it to college, became designated people-hauler for my friend group, and graduated just in time for it to be my sister's first vehicle.

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Steven Silverberg @silverbergastro.bsky.social · 20d

Serious answer: That I believe would fall under academic Rice. Academic Rice is basically the same as it was then; this is the third difference version of the athletic owl since I matriculated. Also that's a really fun project.

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Steven Silverberg @silverbergastro.bsky.social · Aug 24

Please tell me they're already negotiating the Rolaids deal.

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Steven Silverberg @silverbergastro.bsky.social · Aug 22

Really enjoy this one: www.gimmesomeoven.com/chicken-broc... usually with thighs instead of breasts. Works just as well with super firm tofu instead of chicken; also works reasonably well with green beans instead of broccoli.

Chicken and Broccoli Recipe | Gimme Some Oven

This classic chicken and broccoli recipe is full of fresh and delicious flavor, and it's ready to go in a snap!

www.gimmesomeoven.com

Steven Silverberg @silverbergastro.bsky.social · Jul 15

Mildly surprised that the low point isn't Rocky V.

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Reposted by Steven Silverberg

PodKATT @podkatt.bsky.social · Jul 4

Traditional July 4 Programming Note

TCM’s annual airing of 1776 will be a late one this evening

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Steven Silverberg @silverbergastro.bsky.social · Jul 3

And 3) the Republicans held the House from January 2011 on.

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Steven Silverberg @silverbergastro.bsky.social · Jul 3

...Second-threepeat Jordan? (Space Jam notwithstanding)

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Steven Silverberg @silverbergastro.bsky.social · Jun 5

For my money the Saint Louis Zoo is the best zoo in the country. Also Ted Drewes. Science Center is good. And if you enjoy theater and don't mind outdoors see if the Muny has anything of interest on that week--one of the best theater companies in the country.

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Steven Silverberg @silverbergastro.bsky.social · May 23

The Oven of Akhnai! en.m.wikipedia.org/wiki/The_Ove...

Which has many many layers of interpretation beyond the story itself, as well.

The Oven of Akhnai - Wikipedia

en.m.wikipedia.org

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Steven Silverberg @silverbergastro.bsky.social · May 21

Highly recommend the Spokane Indians, who worked with the Spokane tribal leaders to create a uniform in the variant of Salish spoken by the Spokane

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Steven Silverberg @silverbergastro.bsky.social · May 20

It me, the other person equipped to appreciate that.

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Steven Silverberg @silverbergastro.bsky.social · Apr 27

Berkman and Pierzynski, though.

(But you're probably right and this team would probably infuriate me more if I wasn't primarily radio rn.)

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Steven Silverberg @silverbergastro.bsky.social · Apr 27

Even the 2013 team?

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Steven Silverberg @silverbergastro.bsky.social · Mar 30

To be fair, the most impactful bad calls literally evened out--one strike called a ball, one ball called a strike, in the same plate appearance. One could argue that this was simply cleaning up an earlier mistake. (One could also reasonably argue that neither mistake should have been made.)

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Steven Silverberg @silverbergastro.bsky.social · Mar 18

My vague recollection (having not watched The Search in a few years) was that it was less that it had to be Romulan, more that because of some treaty (Khitomer, maybe?) the Federation wasn't allowed to have cloaking devices so the way to get around *that* was to have a Romulan supervise it?

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Steven Silverberg @silverbergastro.bsky.social · Mar 5

Read more about it on arXiv and in AJ! ui.adsabs.harvard.edu/abs/2025AJ..... 14/14

Long-term X-Ray Variability on the Benchmark YSO HL Tau

HL Tau is one of the most well-studied Class I young stellar objects (YSOs), including frequent observations at near- and mid-infrared, (sub)millimeter, and X-ray wavelengths. We present the results o...

ui.adsabs.harvard.edu

Steven Silverberg @silverbergastro.bsky.social · Mar 5

Another possibility is repeated high-resolution spectroscopy of HL Tau to observe how the 6.4 keV iron fluorescence changes over time with the 6.7 keV iron line. If the 6.4 keV line didn't change as the 6.7 keV line does, that could indicate changing geometry rather than changing emission. 13/14

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Steven Silverberg @silverbergastro.bsky.social · Mar 5

BUT to say anything for certain about the nature of the variability would require more data, of course. The observing window for HL Tau in 2020 was six observations over 40 days--a longer baseline (comparable to the ~81 days from K2 Campaign 13) would be beneficial. 12/14

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Steven Silverberg @silverbergastro.bsky.social · Mar 5

A 21 day period would be much larger than the rotation period of the star. BUT it would match the period of an orbiting body in the disk at a circular orbit of ~0.15 AU(!!!). We discuss possibilities for what that could be (accretion funnels, induced hot spots on the star, disk currents). 11/14

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Steven Silverberg @silverbergastro.bsky.social · Mar 5

So, what to make of the variability? The simplest answer is that it's random--we might be seeing parts of "slow-rise, flat-top" flares. But that's not the most interesting possibility, so we decided to consider possible explanations for if it *is* periodic at 21 days. 10/14

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Steven Silverberg @silverbergastro.bsky.social · Mar 5

We were able to reprocess and analyze archival Chandra & XMM-Newton observations of HL Tau from 2000, 2004, 2017, and 2018, and look at how it changes (or doesn't) over time. The temperatures stay consistent around 4 keV. The bright 2020 observations are not as bright as a 2004 flare. 9/14

Figure 9 from Silverberg et al. (2025). Comparison of model fits to HL Tau observations from 2000 to 2020. All models use one collisionally-excited plasma component with variable temperature and a fixed abundance for Fe (and elements with Fe-like first ionization potential) set at the best-fit value from a joint fit to the faint XMM-Newton observations from 2020 and a variable absorption component. Top row: flux (in units of pico-ergs per second per square centimeter) is shown as both absorbed (as observed; blue for XMM-Newton, green for Chandra) and unabsorbed (corrected for absorption; brown). Second row: the plasma temperature for the single plasma component in keV (red) in comparison to 4 keV (dashed gray line). Third row: the emission measure (in units of 10^52 per cubic centimeter) for the single plasma component (red). Bottom row: the hydrogen column density NH (in units of 10^22 square centimeters) of the absorbing material (black). Observing windows are labeled above each column. The observations during the flare identified by G. Giardino et al. (2006) in 2004 are highlighted in gray. The data show that HL Tau is variable, that the by-eye period in 2020 does not necessarily extend to earlier epochs (but might be there?), that the variation in 2020 is due to changing emission rather than changing absorption, and that this pattern does not necessarily hold at earlier epochs.

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Steven Silverberg @silverbergastro.bsky.social · Mar 5

So, what all does this tell us? Our best fit models and the consistent presence of 6.7 keV emission indicate that the spectrum of HL Tau is hot (consistently ~4 keV), on the hot end and bright end of YSOs compared to the COUP observations, but generally consistent with being a Class I YSO. 8/14

Figure 8 from Silverberg et al. (2025). Temperature vs. unabsorbed X-ray luminosity for single-temperature fits to HL Tau (green crosses), in comparison to temperature and unabsorbed luminosities from two-temperature fits (blue and orange circles) to the COUP pre-main-sequence stars (T. Preibisch et al. 2005). The plot shows temperature (measured in keV) in log space on the y axis, as a function of log(X-ray luminosity) on the x axis. The plot depicts blue, orange, and green scatter plots. Blue points represent the temperatures and luminosities associated with cool plasma from COUP, while orange points represent temperatures and luminosities associated with hot plasma. The blue scatter points are flat in temperature as a function of log(luminosity), while the orange points increase linearly as a function of log(luminosity). HL Tau is plotted as green "x" shapes, which overlap with the high-luminosity end of the COUP data. The right y axis shows temperature in millions of Kelvin.

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Steven Silverberg @silverbergastro.bsky.social · Mar 5

Iron fluorescence at 6.4 keV is emission from cold iron in the disk, stimulated by the 6.7 keV emission from the star. The detection here is marginal, but plausible. We also see the Si XIII r-i-f triplet, with f stronger than r, indicating the presence of both hot and cool plasma. 7/14

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