Andy Lloyd's

Dark Star Blog



Blog 69   (December 2018)

(Currently being written)

  News, links, videos and comment   relating to the Dark Star Theory 






New Cometary Planets

Two studies regarding the escaping atmospheres of hot exoplanets have been published this month in the journal Science (1,2). The first is a transiting warm Neptune-mass exoplanet located 20 times nearer its host star than the Earth is to the Sun.  The tail of helium being blasted away from this planet by radiation from its orange dwarf host star extends some five planetary radii out.  The planet, known as HAT-P-11b, is blown up like a helium balloon, according to the researchers who have been studying it (3). 

However, HAT-P-11 is not a young star still blasting away at the primordial atmosphere of a new Neptune-sized world, as you might expect.  Instead, HAT-P-11 is 6.5 billion years old; almost 2 billion years old than our own Sun.  So, why is it still managing to have such a devastating effect upon the Neptune-sized exoplanet in its midst?  Common sense would dictate that you can't have such an effect going on for 6.5 billion years, as the planet would have been eradicated long ago.  Loosely bound helium held in this gaseous 'envelope' would surely leak out into space in considerable quantities over time?  Like with comets repeatedly transiting around their stars at perihelion, you would think that at some point the volatile gases would all get blown away.  Perhaps HAT-P-11b was once a much greater hot Jupiter world which has shrunk to Neptune proportions over time.  Or, perhaps this is a case of inwards migration of this world from further out in the star system.

A similar tail of atmospheric helium is being blasted back from another giant exoplanet, this time known as WASP-69b (5). This world is about a quarter of the mass of Jupiter, making it a sub-'hot Jupiter' object. The discovery of this helium tail was also made using the Carmenes instrument, installed on the 3.5-meter telescope of the Calar Alto Observatory in Spain.  In this case, the host star, is 2 billion years old and just a little smaller than our own Sun (6), making it another orange dwarf.  So, again, this effect isn't due to the young nature of the system - there is a sustained effect taking place over a long period of time if the system has been static for that entire time.  How long can such helium leakage be sustained from this 'evaporating exoplanet'?  Previous discoveries of such leaking exoplanets have included a 'hot Neptune' planet whizzing around a ~9 billion year old red dwarf, Gliese 436 (7).  Evidently, these hydrogen and helium 'envelopes' are remarkably long-lasting!

Why is this important?  Because it indicates that planets can appear like comets, under the right circumstances.  The volatile gases wrapped up in the atmospheres of Neptune-sized worlds can become drawn out into what must be rather fabulous looking envelopes of gas.  These effects are being noticed in the specific cases of exoplanets which are located very close to their stars. This is reasonable in the sense that the planets are subjected to the ultraviolet radiation and stellar winds at this proximity.  But, the reason we're seeing this in these cases is that the planets are transiting the stars, allowing measurement of their extended atmospheres to be taken.  that creates bias towards very close planets.  It may also be true that Neptune-sized planets located further out from these orange and red dwarfs could be exuding atmospheric hydrogen and helium.  Observational bias dictates that we only see the effect with their closer exoplanetary cousins.  This potentially means that Neptune-sized worlds on eccentric, comet-like trajectories might be highly spectacular in nature during their perihelion passages - true cometary planets.


Written by Andy Lloyd,  7th December 2018


1) R. Allart el al., "Spectrally resolved helium absorption from the extended atmosphere of a warm Neptune-mass exoplanet," Science (2018).

 2) L. Nortmann el al., "Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b," Science (2018),

3) University of Exeter Press Release "Helium exoplanet inflated like a balloon, research shows" 6 December 2018

4)  "Planet HAT-P-11 b"

5) Instituto de Astrofísica de Canarias Press Release: "Helium signal reveals the comet-like tail of exoplanet WASP-69b for the first time" 6 December 2018

6) "Planet WASP-69 b"

7) B. Lavie et al. "The long egress of GJ 436b’s giant exosphere" Astronomy & Astrophysics 605, L7 (2017)



Image Credit: Denis Bajram (3)



Image Credit: Gabriel Perez Diaz, SMM (IAC) (4)






More Planets Hidden in Dust

A new survey of protoplanetary disks in the star-forming region in the constellation Taurus have determined that a considerable proportion of the planets emerging from these young disks are super-Earths and mini-Neptune worlds (1,2).  This is in keeping with the high incidence of super-Earths and mini-Neptune worlds among the known exoplanets, and helps to confirm the ubiquitous nature of these worlds.    The survey picked up many fainter protoplanetary disks, which removed some of the observational bias previously favouring the discovery of disks containing more massive, Jupiter-sized worlds.

"The [international] team measured the properties of rings and gaps observed with ALMA and analyzed the data to evaluate possible mechanisms that could cause the observed rings and gaps. While these structures may be carved by planets, previous research has suggested that they may also be created by other effects. In one commonly suggested scenario, so-called ice lines caused by changes in the chemistry of the dust particles across the disc in response to the distance to the host star and its magnetic field create pressure variations across the disk. These effects can create variations in the disk, manifesting as rings and gaps.

"The researchers performed analyses to test these alternative explanations and could not establish any correlations between stellar properties and the patterns of gaps and rings they observed. "We can therefore rule out the commonly proposed idea of ice lines causing the rings and gaps," [Paola] Pinilla [a NASA Hubble Fellow at the University of Arizona's Steward Observatory] said. "Our findings leave nascent planets as the most likely cause of the patterns we observed, although some other processes may also be at work."" (1)

So, super-Earths continue to be the most populous exoplanet category, both in terms of known objects, and the spread of dusty rings they emerge from.  This, despite their seeming absence within our own solar system.


Written by Andy Lloyd,  7th December 2018


1) Daniel Stolte: University of Arizona Press Release: "Unknown Treasure Trove of Planets Found Hiding in Dust" 6 December 2018

2) Feng Long et al, Gaps and Rings in an ALMA Survey of Disks in the Taurus Star-forming Region, The Astrophysical Journal (2018). DOI: 10.3847/1538-4357/aae8e1 


Image Credit: ESA/Herschel/PACS, SPIRE/Gould Belt survey Key Programme/Palmeirim et al. 2013








'Sick n' Beautiful': Moshing with the Alien

I had a bizarre alien encounter at the start of this month.  Not on a distant, secluded mountain.  Not at a top secret research facility in an American desert.  No, it occurred a the most unlikely location: the English town of Reading.  Four stranded aliens from the moon LV-426 (located out in the Zeta II Reticuli system) have successfully integrated into the human community in Rome (could be worse...!).  They while away the time knocking out some banging metal tunes.  These 'Italian' aliens may be 39 light years from Earth, but their creative juices are seemingly unaffected by their desperate plight. 

Hanging out with my metal-mag journo friend, Simon Faulkner (1), I got the chance to meet the outlandish crew from Italian metal band Sick n' Beautiful, whose stage show retains a distinctly alien flavour, including lasers and pyrotechnics (2).  So shazbot!


Written by Andy Lloyd,  8th December 2018


1) Simon Faulkner "Sick n' Beautiful' Wildspiritz Rising, 2018, Issue 2, pp14-21,



Image Credit: Simon Faulkner



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