# Thread: Life on Brown Dwarfs?

1. ## Life on Brown Dwarfs?

Elsewhere I have posted about a recent paper hypothesizing life on Y-type brown dwarfs. (Reference link to follow.) However, I found an older paper on a similar topic.

Stellar Planets and Little Dark Stars as Possible Seats of Life
E.J. Opik, 1964
Irish Astronomical Journal, vol. 6, p. 290-296

Thought this might spark interest here.
Last edited by Roger E. Moore; 2017-Jan-02 at 04:05 PM.

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Originally Posted by Roger E. Moore
Elsewhere I have posted about a recent paper hypothesizing life on Y-type brown dwarfs. (Reference link to follow.) However, I found an older paper on a similar topic.

Stellar Planets and Little Dark Stars as Possible Seats of Life
E.J. Opik, 1964
Irish Astronomical Journal, vol. 6, p. 290-296

Thought this might spark interest here.
Very enjoyable paper. Opik in 1964 makes dead on predictions about extra solar planets.
Last edited by John Mendenhall; 2017-Jan-03 at 02:56 AM. Reason: typos

3. https://arxiv.org/pdf/1611.09074.pdf
ATMOSPHERIC HABITABLE ZONES IN COOL Y DWARF ATMOSPHERES
Jack S. Yates, et al.
We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. To illustrate our model we use a cool Y dwarf atmosphere, such as $\mathrm{WISE~J}085510.83-0714442.5$ whose $4.5-5.2$ micron spectrum shows absorption features consistent with water vapour and clouds. We allow organisms to adapt to their atmospheric environment (described by temperature, convection, and gravity) by adopting different growth strategies that maximize their chance of survival and proliferation. We assume a constant upward vertical velocity through the AHZ. We found that the organism growth strategy is most sensitive to the magnitude of the atmospheric convection. Stronger convection supports the evolution of more massive organisms. For a purely radiative environment we find that evolved organisms have a mass that is an order of magnitude smaller than terrestrial microbes, thereby defining a dynamical constraint on the dimensions of life that an AHZ can support. Based on a previously defined statistical approach we infer that there are of order $10^9$ cool Y brown dwarfs in the Milky Way, and likely a few tens of these objects are within ten parsecs from Earth. Our work also has implications for exploring life in the atmospheres of temperate gas giants. Consideration of the habitable volumes in planetary atmospheres significantly increases the volume of habitable space in the galaxy.

This is the paper on life in the high atmospheres of Y-type brown dwarfs. Weird stuff.
Last edited by Roger E. Moore; 2017-Jan-18 at 03:43 AM.

4. http://iopscience.iop.org/article/10...X/784/1/43/pdf
IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS VI: PROPERTIES OF LARGE-SCALE DISCHARGE EVENTS
R. L. Bailey

Just found a related paper on similar and crossover topic.

LATE ADD: And the paper below.

Last edited by Roger E. Moore; 2017-Jan-18 at 03:44 AM.

5. Originally Posted by Roger E. Moore
https://arxiv.org/pdf/1611.09074.pdf

This is the paper on life in the high atmospheres of Y-type brown dwarfs. Weird stuff.
Tiny microbes, each ten times smaller in radius than a typical Earth microbe. It is tricky to imagine a life cycle for such small lifeforms in such a vast environment..

6. Uncovered some material, new and not-too-old, about life forms in Jovian atmospheres and possibly brown dwarfs. Note that Carl Sagan is among the authors.

Particles, environments, and possible ecologies in the Jovian atmosphere
Sagan, C.; Salpeter, E. E.
REM: The paper that started it all.
"The possible existence of indigenous Jovian organisms is investigated by characterizing the relevant physical environment of Jupiter, discussing the chromophores responsible for the observed coloration of the planet, and analyzing some permissible ecological niches of hypothetical organisms. Values of the eddy diffusion coefficent are estimated separately for the convective troposphere and the more stable mesosphere, and equilibrium condensation is studied for compounds containing Na, Cl, or both. The photoproduction of chromophores and nonequilibrium organic molecules is analyzed, and the motion of hypothetical organisms is examined along with the diffusion of metabolites and the consequent growth of organisms. Four kinds of organisms are considered: primary photosynthetic autotrophs ('sinkers'), larger autotrophs or heterotrophs that actively maintain their pressure level ('floaters'), organisms that seek out others ('hunters'), and organisms that live at almost pyrolytic depths ('scavengers'). It is concluded that ecological niches for sinkers, floaters, and hunters appear to exist in the Jovian atmosphere."

https://en.wikipedia.org/wiki/A_Meeting_with_Medusa
"A Meeting with Medusa" is a science fiction novella by Arthur C. Clarke. It was originally published in 1971.

https://www.cnet.com/news/nasa-juno-...iter-ben-bova/
Real-life sci-fi scenario: Could Juno find life on Jupiter?
REM: SF Author Ben Bova steps in.

http://www.universetoday.com/15134/i...fe-on-jupiter/
IS THERE LIFE ON JUPITER?
REM: Brings up some reasons why it would not work.

http://www.daviddarling.info/encyclo...piterlife.html
life on Jupiter
REM: Good, short overview.

https://arxiv.org/pdf/1510.07052v1.pdf
A Chemical Kinetics Network for Lightning and Life in Planetary Atmospheres
P. B. Rimmer and Ch Helling

There are many open questions about prebiotic chemistry in both planetary and exoplanetary environments. The increasing number of known exoplanets and other ultra-cool, substellar objects has propelled the desire to detect life and prebiotic chemistry outside the solar system. We present an ion-neutral chemical network constructed from scratch, Stand2015, that treats hydrogen, nitrogen, carbon, and oxygen chemistry accurately within a temperature range between 100 and 30,000 K. Formation pathways for glycine and other organic molecules are included. The network is complete up to H6C2N2O3. Stand2015 is successfully tested against atmospheric chemistry models for HD 209458b, Jupiter, and the present-day Earth using a simple one-dimensional photochemistry/diffusion code. Our results for the early Earth agree with those of Kasting for CO2, H2, CO, and O2, but do not agree for water and atomic oxygen. We use the network to simulate an experiment where varied chemical initial conditions are irradiated by UV light. The result from our simulation is that more glycine is produced when more ammonia and methane is present. Very little glycine is produced in the absence of any molecular nitrogen and oxygen. This suggests that the production of glycine is inhibited if a gas is too strongly reducing. Possible applications and limitations of the chemical kinetics network are also discussed.

Constraining Methane Abundance and Cloud Properties from the Reflected Light Spectra of Directly Imaged Exoplanets
Lupu, R.; Marley, M. S.; Lewis, N. K.
We have assembled an atmospheric retrieval package for the reflected light spectra of gas- and ice- giants in order to inform the design and estimate the scientific return of future space-based coronagraph instruments. Such instruments will have a working bandpass of ~0.4-1 μm and a resolving power R~70, and will enable the characterization of tens of exoplanets in the Solar neighborhood. The targets will be chosen form known RV giants, with estimated effective temperatures of ~100-600 K and masses between 0.3 and 20 MJupiter. In this regime, both methane and clouds will have the largest effects on the observed spectra. Our retrieval code is the first to include cloud properties in the core set of parameters, along with methane abundance and surface gravity. We consider three possible cloud structure scenarios, with 0, 1 or 2 cloud layers, respectively. The best-fit parameters for a given model are determined using a Monte Carlo Markov Chain ensemble sampler, and the most favored cloud structure is chosen by calculating the Bayes factors between different models. We present the performance of our retrieval technique applied to a set of representative model spectra, covering a SNR range form 5 to 20 and including possible noise correlations over a 25 or 100 nanometer scale. Further, we apply the technique to more realistic cases, namely simulated observations of Jupiter, Saturn, Uranus, and the gas-giant HD99492c. In each case, we determine the confidence levels associated with the methane and cloud detections, as a function of SNR and noise properties.
.
Last edited by Roger E. Moore; 2017-Jan-18 at 03:40 AM.

7. http://www.projectrho.com/public_html/rocket/aliens.php

Go to the above website and search for: Gas Giant Dweller. Lots of text and illustrations to keep you amused on this topic.

Also:

http://www.centauri-dreams.org/?p=6308
Edwin Salpeter and the Gasbags of Jupiter
"‘The Gasbags of Jupiter’ sounds for all the world like the title of an early 1930s novel that would have run in a venue like Science Wonder Stories. In fact, as Larry Klaes tells us below, the idea grew out of Carl Sagan’s speculations about free-floating life-forms that might populate the atmospheres of gas giant planets like Jupiter. Cornell physicist Edwin Salpeter had much to do with the evolution of that concept, helping Sagan produce a paper that was a classic of informed imagination (and one that led to numerous science fiction treatments as the idea gained currency). Larry’s celebration of Salpeter’s life gives a nod to that paper but also notes his deep involvement in the study of the most distant celestial objects."

Also a trope:

http://tvtropes.org/pmwiki/pmwiki.php/Main/LivingGasbag

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