Cloud behavior expands habitable zone of alien planets

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A new study that calculates the influence of cloud behavior on climate doubles the number of potentially habitable planets orbiting red dwarfs, the most common type of stars in the universe. This finding means that in the Milky Way galaxy alone, 60 billion planets may be orbiting red dwarf stars in the habitable zone.



 


Researchers at the University of Chicago and Northwestern University based their study, which appears in Astrophysical Journal Letters, on rigorous  of cloud behavior on alien planets. This cloud behavior dramatically expanded the habitable zone of , which are much smaller and fainter than stars like the sun.

Current data from NASA's Kepler Mission, a  searching for Earth-like planets orbiting other stars, suggest there is approximately one Earth-size planet in the habitable zone of each red dwarf. The UChicago-Northwestern study now doubles that number.

"Most of the planets in the Milky Way orbit red dwarfs," said Nicolas Cowan, a postdoctoral fellow at Northwestern's Center for Interdisciplinary Exploration and Research in Astrophysics. "A thermostat that makes such planets more clement means we don't have to look as far to find a habitable planet."

Written By: PhysOrg
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  1. There are two ways you could define a habitable zone, — a place where a number of earth species could thrive and a place where complex molecules could exist. As we keep discovering more extremophiles, even the first definition keeps expanding. My conjecture is that the first life we find will stir up a storm of controversy as to it whether it counts as life because it is too unlike life on earth. Its metabolism may be glacial. Carbon may not be central. The other possible surprise is alien life is just like earth, with identical DNA coding, indicating life is like dandelions. I hope I live long enough to resolve that. Given that we are looking primarily at earth-like planets, likely we will first find earth-like life.

    • In reply to #1 by Roedy:

      There are two ways you could define a habitable zone, — a place where a number of earth species could thrive and a place where complex molecules could exist. As we keep discovering more extremophiles, even the first definition keeps expanding. My conjecture is that the first life we find will stir…

      there is a problem with suggesting non-carbon life forms with a glacially slow metabolism

      can’t remember the exact quote but after the Viking landings failed to rule out the possibility of life on mars based on what it had detected, which led to over-excited journos suggesting it meant they might have found life, the response was given along the lines of “equally we can’t rule out those rocks in the photo being martians”

      my view is we whould only be looking for carbon-based life, not just because it’s what we know but because amino acids have already been detected in space so life (as we know it, actually jim) could be very common indeed. finding complex life however, i reckon might be very rare indeed

    • In reply to #1 by Roedy:

      There are two ways you could define a habitable zone, — a place where a number of earth species could thrive and a place where complex molecules could exist. As we keep discovering more extremophiles, even the first definition keeps expanding. My conjecture is that the first life we find will stir…

      Neither of those things are the usual definition of the habitable zone. The HZ is based on climate models. The hot end is marked by the run-away greenhouse effect, or the moist greenhouse effect, which results in a planet losing all of its oceans and converting them into a massive CO2 atmosphere like Venus. The cold end is based on the maximum amount of heating you can get from CO2 before the atmosphere begins to collapse into solid CO2.

      At the hot end, you have the problem that the stratosphere becomes very wet, and the water from the planet is lost through photo dissociation of H2O into H2 and O2. The H2 is very light and escapes, while the O2 remains and forms CO2. Imagine what Earth would look like if you put all of the oceans in the atmosphere and made it all CO2… Earth would look like Venus.

      The cold end of the HZ is calculated from the fact that after you have 35 atmospheres of CO2 and 0 degrees centigrade the CO2 atmosphere begins to collapse into solid CO2 ice.

  2. “Earth-observing satellites have documented this effect. “If you look at Brazil or Indonesia with an infrared telescope from space, it can look cold, and that’s because you’re seeing the cloud deck,” Cowan said. “The cloud deck is at high altitude, and it’s extremely cold up there.”

    Cowan has clearly demonstrated his respect for RD because he didn’t clutter our minds with exactly how cold it is…

    • In reply to #2 by rjohn19:

      “Earth-observing satellites have documented this effect. “If you look at Brazil or Indonesia with an infrared telescope from space, it can look cold, and that’s because you’re seeing the cloud deck,” Cowan said. “The cloud deck is at high altitude, and it’s extremely cold up there.”

      Cowan has clearly demonstrated his respect for RD because he didn’t clutter our minds with exactly how cold it is…

      I you look at the outside temperature during commercial flights the instruments show this.

      All these are interesting pieces of information, many of them changing in interesting ways, telling me something about my journey, something that somebody on board might wish to know. But now, what have we here? “Outside temperature -58°F (-50°C)” http://www.richarddawkins.net/foundation-articles/2013/6/5/outside-temperature-cool-your-jets-who-cares#

      I can confirm similar temperature readings from my own flights.

  3. There have been two opposing hypotheses discussed here from time to time: life (as we know it, or not) is rare, or it is commonplace. The balance of probabilities seems to be shifting towards commonplace. Insufficient evidence, so far, to reach a firm conclusion. May the research continue…

    • In reply to #3 by OHooligan:

      There have been two opposing hypotheses discussed here from time to time: life (as we know it, or not) is rare, or it is commonplace. The balance of probabilities seems to be shifting towards commonplace. Insufficient evidence, so far, to reach a firm conclusion. May the research continue…

      One major factor is “metallicity”. (That is the abundance – or lack of – heavy elements like iron, oxygen and carbon.) This is a separate galactic issue to planetary issue such as the “Rare Earth” where there are suitable elements present.

      https://en.wikipedia.org/wiki/Metallicity

      In astronomy and physical cosmology, the metallicity (or metalicity, also called Z[1]) of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium. Because stars, which comprise most of the visible matter in the universe, are composed mostly of hydrogen and helium, astronomers use for convenience the blanket term “metal” to describe all other elements collectively.[2] Thus, a nebula rich in carbon, nitrogen, oxygen, and neon would be “metal-rich” in astrophysical terms even though those elements are non-metals in chemistry.

      There are also radiation, gravitational disturbance, and collision hazards to the forming life.

      http://astro.unl.edu/naap/habitablezones/ghz.html

      Summation

      The GHZ depends on the balance of two opposing trends. Metallicity decreases as one moves outward in the Milky Way, decreasing the number of potential planets. On the other hand, there are a number of environmental dangers to life associated with the packed inner regions of the Milky Way. Keep in mind that although all of the GHZ factors mentioned above are rooted in solid science, several are very difficult to quantify. The GHZ is an area of research that is still in its infancy and its validity has been challenged by some researchers.

      You will appreciate, that the presence or absence of these elements has a very considerable bearing on the likelihood of life in that area of a galaxy. Star systems have Earth-type planet “habitable zones”, – but so do galaxies.

      http://arxiv.org/abs/0911.3763

      Radial metallicity gradients are observed in the disks of the Milky Way and in several other spiral galaxies. In the case of the Milky Way, many objects can be used to determine the gradients, such as HII regions, B stars, Cepheids, open clusters and planetary nebulae. Several elements can be studied, such as oxygen, sulphur, neon, and argon in photoionized nebulae, and iron and other elements in cepheids, open clusters and stars. As a consequence, the number of observational characteristics inferred from the study of abundance gradients is very large, so that in the past few years they have become one of the main observational constraints of chemical evolution models.

  4. NASA on The sheer significance of clouds

    *I am the daughter of Earth and Water,
    And the nursling of the Sky;
    I pass through the pores, of the ocean and shores;
    I change but I cannot die *
    PB Shelley

    They say that the Dead die not, but remain
    Near to the rich heirs of their grief and mirth.
    I think they ride the calm mid-heaven, as these,
    In wise majestic melancholy train,
    And watch the moon, and the still-raging seas,
    And men, coming and going on the earth.

    Rupert Brooke

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