The abundances of gaseous H 2 O and O 2 in dense cloud cores Eric Herbst & Helen Roberts The Ohio State University.

Slides:

Advertisements

Similar presentations

The Future of Astrochemistry

Advertisements

Formation and Evolution of Molecules Behind Shocks GEORGE HASSEL Dept. of Physics, The Ohio State University Eric Herbst (Ohio.

School of Chemistry, University of Nottingham,UK 1 Why Does Star Formation Need Surface Science? Using Laboratory Surface Science to Understand the Astronomical.

Nuria Marcelino (NRAO-CV) Molecular Line Surveys of Dark Clouds Discovery of CH 3 O.

The Basics Balancing Equations. The Reaction Burning METHANE or any hydrocarbon gives WATER and CARBON DIOXIDE Burning METHANE or any hydrocarbon gives.

Jonathan Rawlings (Lured over to the dark side by Neal Evans) University College London.

Calculations in Chemistry You need to know how to carry out several calculations in Additional and Triple Chemistry This booklet gives you a step by step.

Abundance and Distribution of the HNCS/HSCN isomer pair

Chemical evolution from cores to disks

Observations of deuterated molecules as probes of the earliest stages of star formation. Helen Roberts University of Manchester.

Chem. 31 – 4/20 Lecture. Announcements I Exam 2 –Result: average = 75 –Distribution similar to Exam 1 (except a few more high and low scores) Lab Reports.

METO 621 Lesson 24. The Troposphere In the Stratosphere we had high energy photons so that oxygen atoms and ozone dominated the chemistry. In the troposphere.

Submillimeter Wave Astronomy Satellite and Star Formation Di Li Smithsonian Astrophysical Observatory, CfA July, 2002.

Efficient Simulations of Gas-Grain Chemistry Using Moment Equations M.Sc. Thesis by Baruch Barzel preformed under the supervision of Prof. Ofer Biham.

CHAPTER 3b Stoichiometry.

Chemical and Physical Structures of Massive Star Forming Regions Hideko Nomura, Tom Millar (UMIST) ABSTRUCT We have made self-consistent models of the.

AQUEOUS PHASE CHEMISTRY

ISM Lecture 13 H 2 Regions II: Diffuse molecular clouds; C + => CO transition.

The Chemistry in Interstellar Clouds Eric Herbst Departments of Physics, Astronomy, and Chemistry The Ohio State University.

Robin Garrod September 7, 2010 Herschel and the Formation of Stars and Planetary Systems.

In general, the more atoms in its molecules, the greater is the entropy of a substance Entropy is a function of temperature.

ERIC HERBST DEPARTMENTS OF PHYSICS, CHEMISTRY AND ASTRONOMY THE OHIO STATE UNIVERSITY Gas and Dust (Interstellar) Astrochemistry.

Collaborators : Valentine Wakelam (supervisor)

Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s.

The chemistry and physics of interstellar ices Klaus Pontoppidan Leiden Observatory Kees Dullemond (MPIA, Heidelberg) Helen Fraser (Leiden) Ewine van Dishoeck.

ISM & Astrochemistry Lecture 2. Protoplanetary Nebula The evolutionary stage between evolved stars and planetary nebula CRL 618 – many organic molecules.

Stoichiometry. What the heck is stoichiometry? Stoichiometry: The determination of how much stuff you can make in a reaction from some given amount of.

Rates of Reactions Why study rates?

QUESTIONS 1.What molar fraction of HNO 3 do you expect to partition into fog droplets at room temperature? How does this compare to the fraction that would.

A Gas Grain Model of ISM Cores with Moment Equations to Treat Surface Chemistry Yezhe Pei & Eric Herbst The Ohio State University June 25 th, th.

Qiang Chang, Eric Herbst Chemistry department, University of Virginia

Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8233, MONARIS, F-75005, Paris, France FORMATION OF HYDROXYLAMINE FROM AMMONIA AND HYDROXYL RADICALS.

ERIC HERBST DEPARTMENTS OF PHYSICS, CHEMISTRY AND ASTRONOMY THE OHIO STATE UNIVERSITY Interstellar Chemistry: Triumphs & Shortcomings.

Water in Laboratory J.R. Brucato INAF-Arcetri Astrophysical Observatory, Firenze Italy Water in Asteroids and Meteorites Paris.

Astrochemistry Les Houches Lectures September 2005 Lecture 1

Dark Cloud Modeling of the Abundance Ratio of Ortho-to-Para Cyclic C 3 H 2 In Hee Park & Eric Herbst The Ohio State University Yusuke Morisawa & Takamasa.

ISM & Astrochemistry Lecture 3. Models - History – Grain surface chemistry – H 2, CH, CH – Ion-neutral chemistry – HD, DCO

School of Physics and Astronomy FACULTY OF MATHEMATICS & PHYSICAL SCIENCES The IR-mm spectrum of a starburst galaxy Paola Caselli Astrochemistry of the.

Testing grain-surface chemistry in massive hot-core regions and the laboratory (A&A, 465, 913 and A&A submitted) Suzanne Bisschop Jes Jørgensen, Ewine.

IB1 Chemistry Quantitative 1b.. Topic 1: Quantitative chemistry 1.1 The mole concept and Avogadro’s constant Apply the mole concept to substances.

Astrochemistry University of Helsinki, December 2006 Lecture 3 T J Millar, School of Mathematics and Physics Queen’s University Belfast,Belfast BT7 1NN,

ASTROPHYSICAL MODELLING AND SIMULATION Eric Herbst Departments of Physics, Chemistry, and Astronomy The Ohio State University.

Astrochemistry Les Houches Lectures September 2005 Lecture 2 T J Millar School of Physics and Astronomy University of Manchester PO Box88, Manchester M60.

Helen Roberts University of Manchester

Some Chemistry in Assorted Star-forming Regions Eric Herbst.

R. T. Garrod & E. Herbst The Ohio State University R. T. Garrod & E. Herbst Grain Surface Formation of Methyl Formate Grain Surface Formation of Methyl.

ERIC HERBST DEPARTMENTS OF PHYSICS AND ASTRONOMY THE OHIO STATE UNIVERSITY The Production of Complex Molecules in Interstellar and Circumstellar Sources.

Methanol Photodissociation Branching Ratios and Their Influence on Interstellar Organic Chemistry Thank you Susanna. So I’ve been combining both laboratory.

Donghui Quan & Eric Herbst The Ohio State University.

METO 621 CHEM Lesson 4. Total Ozone Field March 11, 1990 Nimbus 7 TOMS (Hudson et al., 2003)

ERIC HERBST DEPARTMENTS OF PHYSICS, CHEMISTRY AND ASTRONOMY THE OHIO STATE UNIVERSITY Gaseous Chemistry in Interstellar Space.

The Solution Process Electrolytes, non-electrolytes.

Interstellar N 2 toward 20 Aql. Observations of the Interstellar Medium.

IC-1/38 Lecture Kinetics IC-2/38 Lecture What is Kinetics ? Analysis of reaction mechanisms on the molecular scale Derivation.

Impulsive spot heating and chemical explosion of interstellar grains revisited Alexei Ivlev Thomas Röcker, Anton Vasyunin, Paola Caselli Max-Planck-Institut.

ERIC HERBST DEPARTMENTS OF PHYSICS AND ASTRONOMY THE OHIO STATE UNIVERSITY Chemistry in Protoplanetary Disks.

Complex Organic Molecules formation on Interstellar Grains Qiang Chang Xinjiang Astronomical Observatory Chinese Academy of Sciences April 22, 2014.

Sorbonne Universités, Université Pierre et Marie Curie, UPMC Univ Paris 06, CNRS, UMR 8233, MONARIS, Paris, France Reactions of ground state nitrogen atoms.

ERIC HERBST DEPARTMENTS OF PHYSICS AND ASTRONOMY THE OHIO STATE UNIVERSITY Interstellar and Circumstellar Chemistries: The Role of Neutral-Neutral Reactions.

Chemistry 141 Wednesday, October 4, 2017 Lecture 13

On the Formation of Molecules on Interstellar Grains

CC9 - Calculating Involving Masses (p26-30)

First Detection of OD outside the Solar System

Chemistry in Interstellar Space

First Detection of OD outside the Solar System

Molecules: Probes of the Interstellar Medium

Interstellar Ice Formation on Dust Grains

Surface Chemistry: New Methods, New Results

Chapter 7 Chemical Quantities

Methanol emission from low mass protostars

Presentation transcript:

The abundances of gaseous H 2 O and O 2 in dense cloud cores Eric Herbst & Helen Roberts The Ohio State University

Successes for quiescent cores: (1)Reproduces 80% of abundances including ions, radicals, isomers (2)Predicts strong deuterium fractionation

10 6 sites

TYPES OF SURFACE REACTIONS REACTANTS: MAINLY MOBILE ATOMS AND RADICALS A + B  AB association H + H  H 2 H + X  XH (X = O, C, N, CO, etc.) WHICH CONVERTS O  OH  H 2 O C  CH  CH 2  CH 3  CH 4 N  NH  NH 2  NH 3 CO  HCO  H 2 CO  H 3 CO  CH 3 OH X + Y  XY ??????????

MODELLING DIFFUSIVE SURFACE CHEMISTRY Rate Equations

Rates of Diffusion Standard astrochemical (e.g. Hasegawa et al. 1991) for silicates Versions for amorphous carbon and for water ice Slow H (P1): H slowed down to olivine (carbon) value of Pirronello et al. (1997) Slow (P2): all other species slowed proportionally All networks contain evaporation and cosmic-ray desorption; some contain photo processes

MORE ACCURATE METHODS FOR SURFACE RATES Modified rate approach – available but semi-empirical; used here and by a few other groups. Stochastic methods – soon to be available

STOCHASTIC METHODS Based on solution of master equation, which is a kinetic-type equation in which one calculates not concentrations but probabilities that certain numbers of species are present. Can solve directly (Hartquist, Biham) or via Monte Carlo realization (Charnley). Current status: not yet programmed for large models

Some predicted gas-phase abundances (10 K; 10 4 cm -3 ) P2 Energies

Some predicted surface abundances (10 K; 10 4 cm -3 )

TMC-1

SWAS UPPER LIMITS WRT H 2 H 2 O O 2 7.0(-08) 3.2(-06) (Odin claims 7.7(-08) towards ammonia)

Overall and particular agreement: pure gas-phase (low metals)

Same but with C/O = 1

Percentage agreement for gas- grain models 2 nd peak despite depletion

Agreement for specific species Is late-time CO depletion serious???

L134N

SWAS UPPER LIMITS WRT H 2 H 2 O O 2 3.0(-07) 3.4(-06) (Odin claims 1.7(-07) towards ammonia)

Percentage agreement for gas-grain models

Ageement for specific species

Source:  Oph

SWAS VALUES WRT H 2 H 2 O O 2 3.0(-09) <3(-07) (Odin claims <9.3(-08) towards a)

Gas-phase abundances for P2, 20 K, 10 5 cm -3 P1 similar at 15 K

Specific agreement

Same with amorphous carbon grains

CONCLUSIONS Current generation of our gas-grain models gives best agreement for water and oxygen at long times for 10 K sources Chemistry and physics of desorption critical and poorly known Depletion at long times from gas in agreement with results on pre-stellar cores including deuterium fractionation