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HIFOL Colloquia

26.07.2017 – Sebastian Pallmann (Ludwig-Maximilians-Universität, München)

”Scouting Chemical Networks”

Scientific Coordinator

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Prof. Dr. Thomas Henning
Director - Max Planck Institute for Astronomy; Professor at the University of Heidelberg
Phone:+49 6221 528-200

Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg

Personal homepageMPIA Heidelberg

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Prof. Dr. Mario Trieloff
Professor at Heidelberg University
Phone:+49 6221 54-6022Fax:+49 6221 54-4805

Institute of Earth Sciences, University of Heidelberg,, Im Neuenheimer Feld 234-236, 69120 Heidelberg

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Prof. Dr. Oliver Trapp
Max-Planck-Fellow
Phone:+49 (089) 2180-77461Fax:+49 (089) 2180-77717

Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, Haus F; 81377 München

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Heidelberg Initiative for the Origins of Life – HIFOL

Heidelberg Initiative for the Origins of Life – HIFOL

The Heidelberg Initiative for the Origins of Life (HIFOL) seeks to understands one of the most fundamental questions for humanity: how did life emerge on Earth and whether life exists elsewhere in the Universe. HIFOL facilitates a wide range of interdisciplinary theoretical, experimental, and observational research covering the fields of astronomy, physics, geosciences, chemistry, biology and life sciences from a range of research institutes based in Heidelberg. HIFOL brings together researchers from the Max Planck Institute for Astronomy, the Max Planck Institute for Nuclear Physics, the University of Heidelberg, Heidelberg Institute of Theoretical Studies, and Kirchhoff Institute for Physics, each tackling different aspects of the same problem.

Astrophysicists aim to understand how planets form around stars and search for habitable Earth analogues, characterizing their atmospheres, using both space and ground based telescopes. Using both meteoritic and Earth sample, Geoscientists strive to unravel the past evolutionary history of the Solar System and Earth itself, including its interior, crust and hydrosphere. Chemists focus on studying the conditions at which amino acids, nucleotides and their first chains could be abiogenically synthesized and started the self-catalytic replication cycle, while biologists seek to figure out how transition from a non-living to a living world has occurred and where on early Earth it has happened, and how first cells, their membranes, metabolic and reproduction systems have emerged.

<span><br />Artistic view of a protoplanetary disk made of gas and&nbsp;dust grains&nbsp;resembling the young solar system in which protoplanets&nbsp;are forming.&nbsp;The plot on the top right shows&nbsp;the radial distribution of the ratio&nbsp;of abundances of heavy (HDO) to&nbsp;normal (H<sub>2</sub>O) water.&nbsp;The two thick&nbsp;lines shows the results of comprehensive astrochemical&nbsp;modeling of&nbsp;the HDO and H<sub>2</sub>O with the two different assumptions about&nbsp;the disk:&nbsp;1) quiescent ("laminar") disk&nbsp;and 2) turbulent, dynamically-active&nbsp;("2D-mixing") disk.&nbsp;Representative values of the HDO/H<sub>2</sub>O ratio in&nbsp;the Earth ocean's water,&nbsp;comets, and interstellar medium are&nbsp;indicated by&nbsp;straight lines.<br /><br />Ref.:&nbsp;T. Albertsson, D. Semenov, and Th. Henning:&nbsp;Chemodynamical Deuterium Fractionation In The Early Solar Nebula:&nbsp;The Origin Of Water On Earth And In Asteroids And Comets.&nbsp;The Astrophysical Journal, 784:39 (2014)</span> Zoom Image

Artistic view of a protoplanetary disk made of gas and dust grains resembling the young solar system in which protoplanets are forming. The plot on the top right shows the radial distribution of the ratio of abundances of heavy (HDO) to normal (H2O) water. The two thick lines shows the results of comprehensive astrochemical modeling of the HDO and H2O with the two different assumptions about the disk: 1) quiescent ("laminar") disk and 2) turbulent, dynamically-active ("2D-mixing") disk. Representative values of the HDO/H2O ratio in the Earth ocean's water, comets, and interstellar medium are indicated by straight lines.

Ref.: T. Albertsson, D. Semenov, and Th. Henning: Chemodynamical Deuterium Fractionation In The Early Solar Nebula: The Origin Of Water On Earth And In Asteroids And Comets. The Astrophysical Journal, 784:39 (2014)

The underlying rendering shows an artistic view of a circumstellar protoplanetary disk resembling the young solar system in which protoplanets are forming. New modeling (see plot on the right) of the hydrogen to deuterium ratio shows a dependence from its distance to the sun (at radius = 0).

One of the crucial ingredients for life is liquid water. While Earth possesses a water-rich surface, the origin of this water and where it originated from is still unclear. Scientists have found clues by studying the isotopic composition of meteorites that the water has most likely been delivered to Earth by asteroids or comets.

Unlike terrestrial planets that have been assembled from rocks in the inner, hot region of the solar nebula where water was in a gaseous phase, comets and asteroids have formed at farther distances from the young sun and have been able to retain some of the water as ice (bottom right).

In this plot (top right) we show the distribution of heavy water (HDO) to normal water (H2O) between 1 and 30 AU in the young solar nebula, at the age of 1 million years, before the formation of planets have commenced and disrupted it (see the upper right part). The abundance of HDO is very sensitive to temperature and was high initially, about 3%, in the cold, 10 K gas cloud before the young sun heated it up (upper grey line). This value is in strong contrast to the elemental ratio of D to H in the local universe, which is just about 1.5 × 10-5 (bottom grey line).

The HDO/H2O radial distribution was modeled assuming two scenarios:
(1) quiscent ("laminar"; magenta line) and
(2) dynamically active ("2D mixing"; red line), turbulent solar nebula.

The Earth ocean’s ratio of HDO/H2O at about 1.6 × 10-4 is marked by the straight blue line. The HDO/H2O ratios for the Oort cloud family, long-periodic comets are higher by a factor of several compared to the Earth's value (thick grey line in the middle).

As can be clearly seen, the laminar solar nebula model shows the Earth water D/H ratio between 0.8 and 2.5 AU (astronomical units = Sun-Earth distance). For the dynamically active turbulent nebular model such a HDO/H2O value extends toward the larger radii, 9 AU and above. Similarly, the enhanced HDO/H2O ratios representative of the Oort-family comets are achieved within about 2 to 6 AU and about 2 to 20 AU in the laminar and in the turbulent model, respectively. The latter scenario seems more favorable with regards to the measured HDO/H2O in the Earth ocean's, asteroids, and comets.

 
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