2024-04-28 (0) Slashdot posting before the editors mangle it.

As submitted, then edited.

Slashdot's editors often (daily, if not more often) get a slating for errors, and doing, esentially, nothing. Now, as a regular submitter (occasionally accepted - my count is approaching 130 stories ; whingers - get to that count yourself or stop whinging about the site's content) I know that's bullshit, but I'd never actually sat down to record the difference between what I submitted, and what the Ed. (EditorDavid, one of about a dozen) changed before posting the story to the "front page".

I forgot to mention that I fat-fingered the title in my submission : "shy" not "sky".

I should note that this is not my first brush with the editorial "blue pencil" - in the 1990s and 2000s I volunteered on a community (specifically, trade union) newsletter, supervised by a former newsroom (print and TV) editor, Bob Gibb (also a journalist for Lloyd's List, the shipping newspaper). Bob never seriously discouraged my over-wordy, excessive-detail style. It's easy for me to cut down your work, because I rarely need to add anything; just rearrange it, and clarify it. Far easier than writing it myself!

Vale, Bob.

I submitted my story in the wee sma' hoors of 2024-04-29, and it was accepted at 7:34 (time zone unsure ; I'm Zulu) by "EditorDavid", with these revisions : superseded text (deleted by Ed.) ; inserted text.

For clarification, I've no serious disputes with EditorDavid over this. I'm making notes to learn. No, as Bob would appreciate, "shome mishtake shurely"

The naked-eye sky will briefly host a "new" star.

By "star", I do not mean "comet", "meteorite" or "firefly", but genuine [star] photons arriving here after about 3000 years in flight, causing your eyes to see a bright point on the nighttime sky. When it happens, the star will go from needing a telescope ot good binoculars to see, to being the 50th (or even 30th) brightest star in the sky. PARA For a week or so.PARA

Of course, it could just go full-on supernova, and be visible in daylight for a few weeks, and dominate the night sky for months. But that's unlikely.

Named "T Corona Borealis" (meaning : because it is the 20th variable star studied in the constellation "Corona Borealis") is a variable star in the northern sky - circumpolar ( it's now visible all night, all year) for about 60% of the world's population which although normally you need binoculars to see it. PARA For over 150 years it has been known to vary in brightness, slightly. But in 1866, it suddenly brightened to become about the 35th brightest star in the sky. "Suddenly" meaning it was invisible one hour, and near full brightness an hour later. That made it a dramatic "nova" ("new star"), if not a "supernova", and people watched it like hungry haws as it faded over the next weeks, and months, and years.

And it faded back into it's previous obscurity, just wobbling a little, well below naked-eye visibility.

Until the late 1930s, when it started to change it's ESTABLISHED 280-day cyclic pattern. Then, in 1946 ... someone turned the switch back on, and again in less than an hour it brightened about 240 times, again becoming about the 50th brightest object in the sky. Which made it almost unique - a recurring nova. Today, only 10 of these are known, and they're extremely important for understanding the mechanisms underlying novae.

In 2016, "T CrB" (as it is known) started showing a similar pattern of changes to what were seen in the late 1930s. But RockDoctor writes that in 2016, "T CrB" (as it is known) has started showing "a similar pattern of changes" to what happened in the late 1930s when it became one of only 10 "recurring nova" known to science:

In 2023, the pattern continued and the match of details got better.PARA

The star is expected to undergo another "eruption" EN-dash EM-dash becoming one of the brightest few stars in the sky, within the next couple of months. Maybe the next couple of weeks. Maybe the next couple of hours. I'll check the databases before submitting the story, and advise the editors to check too. [I expected this to be deleted]

Last week, astrophysicist Dr Becky Smethurst posted on the expected event in her monthly "Night Sky News" video blog. If you prefer your information in text not video, the AAVSO (variable star observers) posted a news alert for it's observers a while ago. They also hosted a seminar on the star, and why it's eruption is expected Real Soon Now, which is also on YouTube. A small selection of recent papers on the subject are posted here, which also includes information on how to get the most up-to-date (unless you're a HST / JWST / Palomar / Hawai`i / Chile telescope operator) brightness readings. Yes, the "big guns" of astronomy have prepared their "TOO - Target Of Opportunity" plans, and will be dropping normal observations really quickly when the news breaks and slewing TOO the target.

You won't need your eclipse glasses for this (Dr Becky's video covers where you can send them for re-use), but you might want to photograph the appropriate part of the sky so you'll notice when the bomb goes off.

Bomb? Did I say that the best model for what is happening is a thermonuclear explosion like a H-bomb the size of the Earth detonating? Well, that's the best analogue. Understandably, taking a "close" (3000 light years - not close enough?) look at one seems like a good idea.

Preview, check for brightening/ detonation (JD 2460428.55208 = 2024 Apr. 28.05208 mag 9.905 ± 0.0052 - not "Gone" yet!), submit. This CNN article includes a nice animation from NASA illustrating the multi-star interaction that's causing the event:

The stars in the orbiting pair are close enough to each other that they interact violently. The red giant becomes increasingly unstable over time as it heats up, casting off its outer layers that land as matter on the white dwarf star. The exchange of matter causes the atmosphere of the white dwarf to gradually heat until it experiences a "runaway thermonuclear reaction," resulting in a nova [according to NASA]... The NASAUniverse account on X, formerly known as Twitter, will provide updates about the outburst and its appearance.

The BBC reiterates the key data points — that "The rare cosmic event is expected to take place sometime before September 2024. When it occurs it will likely be visible to the naked eye. No expensive telescope will be needed to witness this cosmic performance, says NASA."

Footnote

And, in the tradition I established while writing this post, I'll check the database : JD 2460429.6875, date/ time 2024 Apr. 29.18750, magnitude 10.0. No eruption yet!

2024-04-08 Necessary Conditions for Earthly Life Floating in the Venusian Atmosphere

Reference : arXiv:2404.05356v1 [astro-ph.EP]. Published on 8 Apr 2024

https://arxiv.org/pdf/2404.05356

This is obviously a riposte to the claim, several years ago now, of phosphine in the radio spectrum of Venus' atmosphere. Which has been disputed, the instrument readings disputed, the noise profile challenged ... all the usual suspects.

Just from the title, it sounds like a discussion of the (theoretical) requirements, and potentially their observability, rather than actual new observations.

Now, here's weird - in some of the Blogger Preview modes, ":hover" doesn't work. Or is there something else going on? It's a problem with their preview system. I hadn't noticed that before.

Sections

Abstract
I. Introduction
II. LIFE CYCLE FOR VENUSIAN AERIAL MICROBES
III. REPLICATION RATES AND FALLOUT TIMES
IV. COSMIC RAY EFFECTS ON MICROBIAL LIFE
V. CONCLUSIONS
End of document

I'm trying a different styling. Paragraphs with this "PowderBlue" background are direct quotes - WHY AM I NOT USING BLOCKQUOTE FOR THIS? while my thopughts are on a plain background. Really, semantically, I should be doing this with BLOCKQUOTE. Why am I re-inventing the Semantic Web?

OK, re-considered, I'll use BLOCKQUOTE. Which has a LightYellow background ON HOVER. Forget the PowderBlue.


Abstract

Millimeter-waveband spectra of Venus from both the James Clerk Maxwell Telescope (JCMT) and the Atacama Large Millimeter/submillimeter Array (ALMA) provide conclusive evidence (signal-to-noise ratio of about 15σ) of a phosphine absorption-line profile against the thermal background from deeper, hotter layers of the atmosphere. Phosphine is an important biomarker; e.g., the trace of phosphine in the Earth’s atmosphere is uniquivocally associated with anthropogenic activity and microbial life (which produces this highly reducing gas even in an overall oxidizing environment). Motivated by the JCMT and ALMA tantalizing observations we reexamine whether Venus could accommodate Earthly life. More concretly, we hypothesize that the microorganisms populating the venusian atmosphere are not free floating but confined to the liquid environment inside cloud aerosols or droplets. Armed with this hypothesis, we generalize a study of airborne germ transmission to constrain the maximum size of droplets that could be floating in the venusian atmosphere and estimate whether their Stokes fallout times to reach moderately high temperatures are pronouncedly larger than the microbe’s replication time. We also comment on the effect of cosmic ray showers on the evolution of aerial microbial life.
Back to List.

So, one useful point - that airborne life is more likely in droplets, rather than actual free-floating microbes. Fair point. From which, settling velocities are an approachable topic, while the supply of minerals from the ground isn't so approachable - needs considerably more assumptions. The question of vertical mixing in the atmosphere should make an appearance too.

Back to List.

I. Introduction

Their citations for early discussion of Venus-life as cloud-life starts with "H. Morowitz and C. Sagan, Life in the clouds of Venus?, Nature 215, 1259 (1967) doi:10.1038/2151259a0" - which shouldn't really be a surprise. Sagan gets everywhere.

And they go straight into modelling a "sHigo" (spherical h(H)ydrogen gasbag isopyenic organism) and, with reasonably conservative assumptions get a minimum buoyant size of ~4cm (diameter). That's not insane for a multicellular organism, but a bit much from terrestrial experience of microbes. It also sort of (to me) implies an origin on the ground, getting lofted (evolving into buoyancy) as the environment went from Hadean era (with solar illumination ~20% down on today) to triggering the runaway greenhouse and boiling the oceans. But I'll leave that aside for the time being.RETURN TO THIS

Refereences [4] through [12] cover the controversy about the original detection claim, and raised concerns about the calibration and interpretation of the signals. Clearly these authors feel that the issues raised have bene answered, and the phosphine detection can be treated as valid.

Back to List.

II. LIFE CYCLE FOR VENUSIAN AERIAL MICROBES

This seems to be a re-hash and expansion of :

[14] S.Seager, J.J.Petkowski, P.Gao, W.Bains, N.C.Bryan, S.Ranjan, and J.Greaves, "The venusian lower atmosphere haze as a depot for desiccated microbial life: A proposed cycle persistence of the venusian aerial biosphere." Astrobiology 21, 1206 (2021) doi:10.1089/ast.2020.2244 [arXiv: 2009.06474]

This modle life cycle is predicated on the atmosphere of Venus. Only two references are given, but the structure of the atmopshere has been probed by multiple landers and tested by various combinations of radar from Earth and from (Venus) orbit, so it's not much in dispute.

I'm in the habit of collecting such bits of data on the expectation that I'll need them again. So ... I'll do exactly that, and put the information below. Wait - what's this - from Wiki : Additionally, the clouds consist of approximately 1% ferric chloride.[61][62] Other possible constituents of the cloud particles are ferric sulfate, aluminium chloride and phosphoric anhydride. Well, that's a thing I hadn't considered when making my "supply of minerals" comment above. Hmmm.

Well, let's find some pressure-temperature-altitude data. Ah, good, Wiki has done the searching for me. But ... it seems difficult to generate a chart (in LibreOffice) with multiple ranges for the X-axis, and a common factor for the Y axis. So - subterfuge. Including "tweaking" the drawing in Draw. Not perfect, but it'll do for the moment.

Clearly, I've forgotten the details of Blogger's floating of elements. I'm trying to put the data table beside the graph, but that's not working. I thought I'd figured that out a while ago, but I'll have to work on it again.

And I've got other things to do today.

I need to put some padding onto those rightward elements. Done that, but BLOCKQUOTE needs some attention.

P …

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III. REPLICATION RATES AND FALLOUT TIMES

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IV. COSMIC RAY EFFECTS ON MICROBIAL LIFE

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V. CONCLUSIONS

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Tables

Table with properties set - caption, width, border-style, border-width, border-coloUr, ... border-collapse, ...
Heading 1 Hdg 2 Heading 3
Row 1 CS 1 ; CP 11 R1 C2 CS 2; CP 3 R1 C3 CS 5 ; CP4
Row 2 CS 2 ; CP 12 …R2 C2 CS 6; CP 6 R2 C3 CS 7 ; CP 8
Row 3 CS 3 ; CP 13 R3 C3 CS 9 ; CP 16
Sections
Heading
a
b
c …

  • ul
  • ul
  1. reversed Specifies that the list order should be reversed (9,8,7...)
  2. start number Specifies the start value of an ordered list
  3. type 1,A,a,I,i
  4. ol
  5. ol


End of Document
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(Footer)

2024-04-27 (2) Back to the backlog. Collection.

Well, I've got a backlog to try to work my way through. Thick end of 100 days, which would be pushing 10,000 papers, if I looked at everything. But I've already blindly thrown about 90% of that over the side. Probably including some tatties. Oh well. Modify the default template with the "fonty" stuff.

Nothing attractive in the first part of the pile. But I should go back to the previous post and add anything I see in the archives for T.CrB.

Did the T CrB (see - even i'm not consistent in the abbreviation used!) submission to Slashdot - with a Tyop in the title. Quick look through another day's worth of IArχiv, then bedtime. Bit of a collection post.

Article List.

Articles read and things studied this month, April 2024.
Link Description
HTML Recent HTML Learnings - 2024-04
T CorBor Article submitted to Slashdot
Quadruple massive star system Arχiv, non-planar system (decided against it)
NGC 708 A 10-billion solar mass black hole in a low dispersion galaxy with a Kroupa IMF (decided against it)

Recent HTML Learnings - 2024-04

I learned a little about using external fonts, specifically from Google, but I should be able to generalise it, if it's worthwhile. (I'm dubious enough about Google's committment to keeping these fonts generally available, or any of their self-interested "philanthropy", but that'll be another thing to work on.)

This block should be in a silly font. "Google Monoton ". Nope, I'm borked again. Forgotten how to make it work. [...]

Fixed it now. Different funny font, "Jacquard 12 Charted" at 30 pix.

Back to RTFM, and improve my notes.

Where did I (initially) go wrong? I've got (1) the link in the HEAD section, then (2) the font family chosen in the (CSS)STYLE section. (I use PRE for demonstration. Meh.)

The example given encloses the URL for the stylesheet link in only one set of quotes - which is problematic when there are spaces in the font name. Let's get rid of that (and put single-quotes on the outside) for starters.

Yep, that did it. So, names with spaces now.

That looks a bit odd. (Note the different quote marks.) rel="stylesheet" href='https://fonts.googleapis.com/css?family=Monoton|Major Mono Display' works, but I'm sure there were warnings about mixing names with spaces in there. Oh well. Lesson learned, into the default header it goes.

I've also done a little paragraph-level formatting with p style="font-size:30px ; font-family:'Jacquard 12 Charted'" above. Note the arrangement of different quotes in there.

Back to Article List.

T Corona Borealis - submitted

The naked-eye shy will (briefly) host a new star. Fuck - check the BODY and you'll have a tyop in the title!

Well, I do hope the editors do catch that. At least I'm a lot more polite about them than the average Slashdotter.

Back to Article List.

A Quadruple System with A Massive Star

Arχiv 2403.12771

Looks moderately interesting. Total system mass ~25 M, of considerably differing sizes, thus MS-durations. Not co-planar (now that's surprising - worse then Pluto-Sun-Jupiter, without the tail-wags-doggery). There's a chain of logic implied from the distribution of system masses to the range of bound NS-NS and NS-BH potential future systems, and a difference between expected [NS] and [BH] occurrence rates seen in GW mergers. Which will need more brain cell than I have tonight. This morning, even.

Abstract

Hierarchical massive quadruple systems are ideal laboratories for examining the theories of star formation, dynamical evolution, and stellar evolution. The successive mergers of hierarchical quadruple systems might explain the mass gap between neutron stars and black holes. Looking for light curves of O-type binaries identified by LAMOST, we find a (2+2) quadruple system: TYC 3340-2437-1, located in the stellar bow-shock nebula (SBN). It has a probability of over 99.99\% being a quadruple system derived from the surface density of the vicinity stars. Its inner orbital periods are 3.390602(89) days and 2.4378(16) days, respectively, and the total mass is about (11.47 + 5.79) + (5.2 + 2.02) = 24.48 M. The line-of-sight inclinations of the inner binaries, B$_1$ and B$_2$, are 55.94 and 78.2 degrees, respectively, indicating that they are not co-planar. Based on observations spanning 34 months and the significance of the astrometric excess noise ($D>2$) in Gaia DR3 data, we guess that its outer orbital period might be a few years. If it were true, the quadruple system might form through the disk fragmentation mechanism with outer eccentric greater than zero. This eccentricity could be the cause of both the arc-like feature of the SBN and the noncoplanarity of the inner orbit. The outer orbital period and outer eccentric could be determined with the release of future epoch astrometric data of Gaia.

Looks worth a read.

Back to Article List.

Triaxial Schwarzschild Models of NGC 708: a 10-billion solar mass black hole in a low dispersion galaxy with a Kroupa IMF

2403.12144

I met Kroupa IMFs last week - oit's the 4-class IMF, with different power laws indices for each successive mass class.

Look at this one too. Might help me modelling the IMF (and other models).

That's enough for tonight.

Got up to the start of March (mostly by throwing lists away un-examined). I need to thin down (or increasingly specialise) IArχiv for the weighted list. No more work here, just separate posts tomorrow on the "interesting" stuff.

Back to Article List.

End of Document
Back to List.

2024-04-27 (1) T CorB - a recurrent nova.

Articles studied this April - some of which might go to Slashdot.
'T' Corona Borealis (T CrB) - A recurrent nova in Corona Borealis likely to erupt Real Soon Now
T CrB - Recent papers in Arχiv.
T CrB - Distance and position on the sky.
T CrB - When ? The $64.000.00 question.
End of document

'T' Corona Borealis (T CrB) - a Recurrent Nova, about to recur.

This came off DrBecky's YT channel, which is good fun and well worth the effort. Another useful link is a seminar held for the AAVSO (American Association of Variable Star Observers - don't worry, unlike most Americans, they acknowledge there is a Rest Of the World) on the subject last year. Essentially, if you're a variable star observer, in the Northern hemisphere, they want you to be checking it as a regular part of your sweeps (news announcement). If you've got a spectroscopic rig on your telescope, particularly calibrated for UV spectroscopy that can detect neon lines (see seminar video), then your observations are particularly encouraged.

The last two times (or maybe 4, or 5 - there are interesting hints of pre-1800 CE observations) this star went into "eruption", it passed from well below naked-eye visibility (good binocular visibility though - it doesn't need a big scope) to about the 50th-brightest star in the sky in a matter of (at most) a couple of hours. (That's from two events, involving 4 observers - 2 discoverers, and two who were too early ; so it's a good bet for this time around too.) Thus, even if you don't catch it in eruption, yours could be the last pre-eruption brightness record - which itself is a very valuable datum.

Dr Becky and the seminar provide the details on the star ; no point in me repeating their statements here. There's a small chance of the eruption this time being a supernova (type 1-SN, even - the ones used as "standard candles" for distance measurement across the universe), which adds to the importance of understanding it as well as possible. In theory, the system could go through many of these eruptions before eventually triggering the SN - but how many ... theory doesn't have a good answer for that.

It's not hard to find - follow the full length of the handle of the Plough asterism ("Big Dipper" in America - as if "dippers" were more common implements than ploughs ; odd that) from the Plough-share, through the "wedge" of Boötes (with red Aldebaran at the tip of the wedge) but not as far as the "Square of Hercules" ; Corona Borealis is the semi-circle of stars between Boötes and Hercules. Get to know what the area looks like. When the system "goes", there will be a new star there. (At the time of writing (2024 Apr. 27.55056), the AAVSO reported a brightness of 10.034 - which means it hasn't "gone" yet. When it goes, it'll make it to about magnitude 2. THe AAVSO website above lets you interrogate their database (but please don't melt their servers if you hear of the eruption having started - scientists and actual contributors will need it - unmelted!)

T.CrB finder chartHere is a "finder chart" of the area (astronomical convention : bigger blobs = brighter stars). The field of view is 15 degrees square, so your fist at arms-length will approximately cover the arc of stars comprising the Corona Borealis and the target a finger's width to the south (away from the Pole Star !? ) from the semicircle of the "Northern Crown".

Get used to what this part of the sky looks like. Some time this year, for a week to 10 days, it's going to look visibly different. Just maybe, you'll be able to see it by daylight. The constellation is about circumpolar from the UK, so you should be able to see what is happening without checking your clock first. Which includes the state of the clouds.

I missed an important point. Going on past events, the eruption will last between a week and 10 days.


Recent papers in Arχiv.

Obviously, I should look at what has recently been published on Arχiv about T.CrB. And, to my surprise, it's already in my search history. What do we have ?

I should note that the naming is a little lax. The "T CrB" ("identifier" in "constellation") code is variably capitalised. The star has different names in various catalogues as well, but "T CrB" is concerned with the variable star. The HD catalog name (for example) might be used if you were working specifically on the (relatively) normal star, not the variable in the system. But if you were looking at the position (does it wobble?), you might look at the GAIA catalogue entry.

Arχiv references encode the year, month and sequence-within-month as "YYmm.sequence". So you've got the date in the reference.

Recent additions to Arχiv concerning the recurrent nova T.CrB
Code Title Comment
https://en.wikipedia.org/wiki/Nova#Recurrent_novae Nova Wiki article on recurrent novæ.
Includes a list of the known recurrent novæ.
https://en.wikipedia.org/wiki/T_Coronae_Borealis T CrB Wiki article on T CrB
https://arxiv.org/search/?query=T+CRB&searchtype=all&source=header Arχiv search Returns a list of 128 results (today ; this will change).
arXiv:2312.04342 Accretion in the recurrent nova T CrB: Linking the superactive state to the predicted outburst The 1946 had a dip then a brightening of about 1mag in the years before the 1946 eruption, and similar trends have been seen in 2023, leading to the current expectations.
arXiv:2308.13668 The recurrent nova T CrB had prior eruptions observed near December 1787 and October 1217 AD Discussed in the "webinar" referreed to above.
arXiv:2307.00255 The "super-active" accretion phase of T CrB has ended More discussion of the recent changes.
arXiv:2207.14743 Stringent limits on 28SiO maser emission from the recurrent nova T Coronae Borealis Looking for signs of "mineral dust" being cooked by the variable star.
arXiv:2009.11902 Increasing activity in T CrB suggests nova eruption is impending This event has been expected for some time!

The blue entry above adds context in the Abstract, with my [annotations] :

T CrB is known to display the SiO [basic unit of silicate minerals] fundamental vibrational feature at 8μm. [microwave radio signal] When the anticipated eruption occurs, it is possible [possible!] that the shock produced when the ejected material runs into the wind of the red giant in the system may be traced using SiO maser emission.

So ... they're measuring the "quiet" state signal (nothing much visible) so they can compare any "eruption" state signal to the measurements already "in the can". "We find no evidence for such emission." is useful "negative" science.


T CrB - position on the sky and range.

Up in the main message, I described how to find the object "on the sky" :
- follow the full length of the handle of the Plough asterism ("Big Dipper" in America - as if "dippers" were more common implements than ploughs ; odd that) from the Plough-share, through the "wedge" of Boötes (with red Aldebaran at the tip of the wedge) but not as far as the "Square of Hercules" ; Corona Borealis is the semi-circle of stars between Boötes and Hercules. And don't forget - on previous "eruptions", the star became about the 50th (to 30th) brightest on the sky, for a week and a bit.

That's not quite the complete story. For fullness you'd normally also want to know the range. People tend to get (unduly) worried about potential big explosions in our backyard.

The Wikipedia page (link above) cites a report from the GAIA team of a parallax of 1.2127 ± 0.0488 mas, which equates to a distance of 802 parsecs (± 30 parsecs) or 2598.48 (± 97) light years.

Which is close enough for me to think it interesting, even if it's not quite far enough to be convincingly safe. But a strongly beamed explosion ... could be interesting. The results of the eruption could be very interesting.

Back to Article List.

When ? The $64.000.00 question.

When making predictions, the "when" bit of the prediction isa always important. When the star entered it's "active" phase (as seen about 1938 to 1946) in 2016, fingers were pointed at 2024. When the star entered the brightness dip (see the "seminar" in the man section) phase, the date was revised to 2024, May, with a ± of about 0.5 years (6 months). We're currently nearing the mid-point of that range, but no updates on the expected time. So ... weeks to months, possibly days to hours. I'll check the figures again when I submit this to Slashdot. (Checked for brightening on JD 2460428.55208 = 2024 Apr. 28.05208 mag 9.905 ± 0.0052 - not Gone yet!). Saved submission in this blog, to see how the editors mangle it. The "check for brightening" string should be pretty unique.

Back to Article List.

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