Two planets around Kapteyn’s star

 G. Anglada-Escud ́e et al, https://arxiv.org/pdf/1406.0818.pdf with a small football team of co-authors.

I noticed the paper while searching for something else on Arxiv ; the title hooked me, but on second reading I'm realising it's old (2014) work.

Kapteyn's Star is one of the closest stars to the Solar system (well known) ; it's a red dwarf with a parallax of 0.25 arcsec (4 parsecs). It is considered a halo star - a star passing through the Milky Way's disc, but generally residing in the galaxy's halo). Proper motion just under 9 mas/year. Discovered about 1897 in compilation of the Cape photographic Durchmusterung. It has a low spectroscopic rotational speed (v.sin(i) <~3km/s) and low metallicity. It is considered a pretty ancient star, and possibly derived from the Omega Centaurus galaxy's halo into the Milky Way's halo, stripped off during the collision.

Located in Pictor, southern hemisphere. It moves, relatively quickly.

Between 1999 and 2013, using several devices, a sequence of spectra were taken and yield a periodic drift with two period peaks of 121 and 48.6 days.

With a low-mass primary, and relatively large planets (4.8 and 7.0  Msin(i)_earth) the orbits seem stable on the 10 Gyr timescale (appropriate for a merger star).

This work has been challenged several times, but seems to survive it reasonably well.

Beringia Bathymetry

The question of the "peopling of the Americas" has arisen - again. A claim of a 30-odd kyr collection of worked points suggesting a very pre-Clovis occupation. Interesting, but the "tools" aren't wonderfully convincing.
A while ago, I looked at the seabed of Beringia - I think some idiot (Musk? or one of his hangers-on?) had suggested tunnelling a "hyperloop" from Anchorage to Vladivostok or some such stupidity. Well, here's the seabed topology :

(Figure made with GeoMapApp (www.geomapapp.org) / CC BY, using GMRT data from Ryan, W. B. F., S.M. Carbotte, J. Coplan, S. O'Hara, A. Melkonian, R. Arko, R.A. Weissel, V. Ferrini, A. Goodwillie, F. Nitsche, J. Bonczkowski, and R. Zemsky (2009), Global Multi-Resolution Topography (GMRT) synthesis data set, Geochem. Geophys. Geosyst., 10, Q03014, doi:10.1029/2008GC002332.)

From the tunnelling point of view, the shortest route involves a sump at 40 or so metres below sea level, plus some actual rock thickness below sea bed - unless you want your tunnel/tube exposed to wave activity, which is a whole 'nother world of engineering fun. The Musk-o-philes don't seem to think of things like that - they're seriously disconnected from reality. Oh, the tunnel is evacuated, which is goign to make every extra 10m of water quite a significant load for collapse loads.
To the state of Beringia at the alleged time of the settlement of the Americas, the southern margin seems to have been a complex of small islands - good for island-hopping by small craft ("kayaks" or equivalent) and that would have been the case for a long time before and after the sea level low stand, but the islands changing in detail.

Humans probably had raft, if not small craft technology from around 60kyr BP, when humans made it to Australasia. Combining that with sewing - for making tailored clothing - and most subsequent humans would have had most of the technologies to island hop along the south coast of Beringia and/ or the Aleutian islands without making any irreversible "leap of faith" journeys. Since humans had been doing this along the preceding 10,000km of the Asian-Pacific coast, it's almost surprising that it took so long for humans to reach the Americas.

Sector collapse

When we were doing the Vulcanology trip to Tenerife, a couple of the stops were to examine the faults bounding the Guimar (SE coast) and Santa Cruz (N coast) collapses. Always worth thinking about, even without the fears stirred up by that Portsmouth (?) hazard research centre.
Well, Prof Ceiling Cat Emeritus has been posting about his current jaunt around Hawai'i, and one look at the geography of Oahu made me think "sector collapse" again.

Oh dear, that's not good looking. That looks like lumps of islands 10km by 20km which have broken off and slid over 50km down the seabed slope.
What does the profile look like? (following the white line in the bathymetry plot)

10km NE-SW by 20km NW-SE by 1.5km thick. That's a big chunk of rock. The tsunami that hit the Pacific coasts (and particularly the British Columbia to Washington section) would have been ... unhealthy to see. I wonder what the date was.

For comparison, here's the most recent slump from the North side of Tenerife.

(250m bathymetry contours, bolded at 1000m intervals, for all images) The characteristic "lumps on the sea floor" of a slump can be seen. In the profile you can estimate the thickness of the largest lump, though this slump seems to have fragmented more than the Hawai'i example above.

 To a first approximation, say 5km by 3km by 0.25km. More detailed mapping with sonar shows that a lot of the seabed has rough areas which are interpreted as earlier generations of slump. Upwards of 20 slumps have been identified around the Canaries archipelago. 
Probably the most recent slump around Tenerife (unless it has "gone" while I'm typing) is from the side of the island facing Gran Canaria.

 The profile shows how steeply the islands drop off away from the volcanic centres.

Note the level of the inter-island gap - 2.5km below sea level - compared to the abyssal plain to the North at over 3.5km below sea level. There is around a kilometre of fill in this gap which hasn't accumulated to the North.

 Since the turn of the millennium there has been considerable speculation about the possibility of major landslides from the flanks of volcanic islands in general, and the Canary archipelago in particular. While concern about the particular claims concerning a West-flank collapse of La Palma have somewhat abated, there are certainly major landslip features around ocean islands. The recent (22 December 2018) flank collapse of Anak Krakatoa in the Indonesian archipelago killed over 400 people, making the point that these things do indeed happen.  

Slashdot submission : An alternative, but common, astronomical habitable zone

Another interesting paper caught my attention.

Yet another provocative paper emerges onto Arxiv from Harvard's Lingam and Loeb.

Today they estimate the volume of space occupied by habitable zones (regions where liquid water is stable) in brown dwarf not-quite stars. They find that it could be orders of magnitude greater than the volume in the atmospheres of Earth-size planets.

Brown dwarfs are masses of gas which are too small to sustain nuclear fusion (so, they're not stars), but can have a brief period of fusion of deuterium or lithium shortly after formation (so they're not planets ; the boundary size is under debate). After this burst of energy, they slowly cool, for billions of years. This leads to a large volume of the star's outer body — or atmosphere — with potentially attractive temperature and pressure. If the brown dwarf is orbiting with a larger star, there may be enough light to allow photosynthesis. Supply of chemicals is uncertain, but not impossible.

While this paper is speculative, the prospects for detecting such life by spectroscopy are plausible with observational instruments being designed at the moment.

Previous work on abiogenesis and the origin(s) of life has speculated that life could persist in the atmospheres of Venus and Jupiter, using comparable pressure-temperature arguments. In this respect, the proposal is more conventional.

I don't know what they're putting in the water at Harvard, but Abraham Loeb is producing a lot of interesting stuff over the last year or so. 

If Slashdot take up the submission, I'm expecting the nerd-claimants there to raise questions about the availability of chemical elements. I don't see that much of a problem, since the relatively gentle convection on Jupiter (driven by the heat release of helium settling down though the hydrogen) is enough to put interesting amounts of hydrocarbons, ammonia, sulphur compounds up to almost the tops of the clouds, producing the visible colour bands and belts of the planet. If anything, the convection on a brown dwarf would be stronger, bringing heavier elements to higher in the body's structure. (Like Jupiter, unlike Venus, it probably doesn't have a fluid-to solid "surface".)

There remains a "dilution problem", but life managed to get around that on Earth, so I don't see that as a killer argument. 

Quite similar arguments about internal temperatures were being knocked around when Brown and Batygin produced their "planet nine" proposal in early 2016, and people were trying to work out if it would be detectable in infra-red detectors. That Brown is now (2019) getting surveying time on the Subaru telescope says what the rest of the astronomical community thought about that. 

Planet Nine (BB2016 ; there are others in the literature) is estimated to be around 10 Earth-masses (about 1/32 Jupiter-masses) so will have cooled a lot faster than a Jupiter-mass planet, let alone a 30 Jupiter-mass (mid--range) brown dwarf. So that proposed planet isn't a credible life habitat. Well, it's less credible than Europa.

Slashdot Submission, A second Interstellar object?

In the aftermath of the recognition of 1I/`Oumuamua as an object originating from outside the Solar system, people have been trawling through the archives for other possible similar events. One such archive is CNEOS, which incororates a list of fireballs - objects that have hit the Earth's atmosphere such as the 2013 Chelyabinsk meteor, or the powerful event over Russian Kamchatka in December of last year.
Searching this database a small event (about 100tons TNT equivalent) of 2014 stood out - the orientation of it's path, time and date allowed it's trajectory to be worked out and back-tracked, showing that it probably came to Earth from outside the Solar system. Before entering the Solar system, the object had a velocity of some 43.8km/s with respect to the Sun and was slightly accelerated by the Earth's gravity before impact. When compared to the "Local Standard of Rest" (LSR, the vector of objects orbiting the galactic centre with the Sun), the object's computed speed was some 60km/s, and at This implies that it was never bound to the Sun. Unlike 1I/`Oumuamua, the bolide was also at a considerable angle to the LSR. If accepted as an interstellar object, this second such body starts to flesh out the size and frequency distribution of such events. The possible power-law distributions within these limits are compatible with the distribution of small Kuiper Belt Objects, which includes objects liable to be scattered from the Solar system in future stellar encounters.
The location of the fireball - above the Pacific Ocean NE of Papua New Guinea does not make finding remains very likely. However, the last word of the paper's Discussion is "panspermia" so "Aliens" graphics can be used.

I need to do a bathymetry for this one too.

Put onto Slashdot as a submission.

I've done the bathymetry. The red star shows the location of the fireball ; the white line is the line of the profile.

Data is from GMRT and CNEOS, plotted using www.GeoMapApp.org.

Pleistocene Indonesian bathymetry

With the recent announcement of another quite old, non-human hominoid in SE Asia, once again people are asking questions about how such humanoids got there, as if these non-human animals were stupid, or incompetent, or ... whatever reason.
So, I did a bit of bathymetry work, since I've got tools to hand. I'm sure I'll use these again.
The common estimate for the decrease in sea level (compared to today) at the height of the last ice age, is 100m, so I've adjusted the rainbow colour scale to cover the 90-110m range ; anything deeper than that is marked in blue ; anything shallower is white ; present day exposed land is given an altitude palette.

Is Luzon isolated from the mainland by deep water? 

On this first plot, there is an obvious wide gap to the north. It actually goes down to several km depth, but since you normally drown in the top few metres of water, that doesn't really matter. The minimum sea passage is several hundred kilometres. That's quite a challenge.

 Moving to the southern approach, the question is more complex. At a 100m lower sea level, there is no "dry" route to Luzon, but several of the channels are down in the few-tens of km width. These would certainly be easier for people to have crossed, regardless of their species. Whether that is how the Luzon hominids got in ... is at the moment a judgement call. But if I were looking for places to search for bone-bearing deposits, that's where I'd start. 

This next picture I just anticipate I'll need at some point. Constructed from the same data (GMRT) and with the same shading to differentiate 100m+ versus 100m- water depths, it shows the context of the Homo Floresiensis discovery site (Liang bua cave, my typo). You will note that at least one water crossing of about 30km or larger is needed to get from mainland Asia to Liang bua.
The sea to the north of the two Nusa islands is known as the Flores Sea, for which the species was named.

Plots done using GeoMapApp, www.geomapapp.org and the GMRT dataset they pick up.

Fake dinosaur footprint.

Very quick post.

Geology class
A faked dinosaur footprint. A4 clipboard for scale.
On a field trip to Arran.
In 1985
We don't know who carved this fake dinosaur footprint, but the carver didn't notice that he (she?) cut across several sediment beds (NNE to SSW lineation in this view), marking it as an evident fake.

Photo has suffered from fungus and bad storage for years before being scanned. The carving is pretty unrealistic too.
Prompted by the footprints recently reported from Skye.

"BrexitExit" and the costs of Hubris

In the aftermath of the disastrous (for the Tory Government) 2017 general election (for clarity - the one in June ; I remember 1974 and the two general elections that year, and I'm not going to rule out a second one this year), the question of how badly the UK Government's team at the upcoming "Brexit" negotiation will be weakened is obviously of importance. On one side will be a team from the UK's DUP-CUP Coalition of Chaos, constantly looking over their shoulders to see if they're getting the sack this afternoon, and on the other side a team of professional negotiators with homes to go to and careers that won't be badly affected one way or the other by the result. It's not going to go the way that the Government  or their Brexit supporters want. And the deal that will be aimed at by the professional EU negotiators will be one that is so bad for Britain that it becomes an unavoidable question whether or not it is worth carrying on.
 The UK Government is going to have to try to exit from Brexit. Hence the tag "#BrexitExit".

At that point, one would expect - "require", even, since part of the charge of the EU government is to extend and enhance the EU - the EU negotiators to extract some political payment. If membership of a club is considered an attractive thing, then defectors must be punished, and punished publicly. 

I think one of the high probabilities of a demand for suspending Article 50 and ceasing Britain's efforts to leave the EU will be Britain signing up for the Euro.

The fact that this would be utterly repugnant to many of the political engineers of the whole Brexit debacle would, of course, be one of the motives for making this demand. There are swords which have not been fallen upon, and that is not an acceptable end point of the process. 

I'm also trying to remember an aphorism to the effect that "Those who the Gods wish to destroy [for their sin of hubris], they will first drive insane." [See footnote-2]

Boy, was PM Theresa May suffering a severe attack of hubris when she called the election, and now it's either Furies or Harpies that are keeping her awake at night.

---

Links : (submitted as comment/ idea to a journalist on NZZ, Neue Zürich Zeitung) Back-link?

Footnote 1 : "DUP-CUP" Democratic Unionist Party is well known ; the official name of the Tories has always (well my political lifetime, at least) been the "Conservative and Unionist Party" ; normally Tories refer to themelves as "Conservatives", but when first toadying to the DUP, May started using the full name, and telegraphing what was coming by that wording.

Footnote 2 :  That phrasing actually seems to be from the 1870s by Longfellow, but the concept has been traced back via multiple re-uses to Sophocles' Antigone lines 622-624

that a man can reason the bad
into good, when a god
seduces his wit.

 That's the common (in 5th century BCE Athens) condemnation of Sophists.