About

Professor Karin Öberg is a member of the Öberg Astrochemistry Group at the Center for Astrophysics | Harvard & Smithsonian. Her research explores the origins of chemical complexity in space and how these processes influence star and planet formation, with a particular focus on the bulk and organic compositions of young planets. Her work encompasses laboratory experiments aimed at simulating the chemistry and physics of interstellar grain mantles, as well as radio and infrared observations, often at high spatial resolution, and astrochemical theory. She investigates how astrophysical processes affect interstellar chemistry and how spatially and spectrally resolved observations of molecular lines can be used to probe star and planet formation. Her recent studies include examining sulfur chemistry in planet-forming disks, utilizing the ALMA interferometer to observe molecules such as CS and H2CS, and developing astrochemical disk models to understand the formation of key sulfur carriers in disks.

Research topics

• Astrophysics
• Physics
• Computer Science
• Astronomy
• Optics
• Environmental science
• Geometry
• Astrobiology

Selected publications

• An Ice Age JWST inventory of dense molecular cloud ices

  Nature Astronomy · 2023 · 325 citations

  • Computer Science
  • Environmental science
  • Astrobiology

  Icy grain mantles are the main reservoir of the volatile elements that link chemical processes in dark, interstellar clouds with the formation of planets and the composition of their atmospheres. The initial ice composition is set in the cold, dense parts of molecular clouds, before the onset of star formation. With the exquisite sensitivity of the James Webb Space Telescope, this critical stage of ice evolution is now accessible for detailed study. Here we show initial results of the Early Release Science programme Ice Age that reveal the rich composition of these dense cloud ices. Weak ice features, including 13CO2, OCN−, 13CO, OCS and complex organic molecule functional groups, are now detected along two pre-stellar lines of sight. The 12CO2 ice profile indicates modest growth of the icy grains. Column densities of the major and minor ice species indicate that ices contribute between 2% and 19% of the bulk budgets of the key C, O, N and S elements. Our results suggest that the formation of simple and complex molecules could begin early in a water-ice-rich environment. Using JWST, the molecules seen in planetary atmospheres can be traced back to their cold origins in ices formed in dense interstellar clouds, before the onset of star formation, revealing that chemical diversity and complexity is achieved early.

  DOI

• Molecules with ALMA at Planet-forming Scales (MAPS). IV. Emission Surfaces and Vertical Distribution of Molecules

  The Astrophysical Journal Supplement Series · 2021 · 139 citations

  • Astrophysics
  • Physics
  • Astronomy

  Abstract The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a unique opportunity to study the vertical distribution of gas, chemistry, and temperature in the protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, and MWC 480. By using the asymmetry of molecular line emission relative to the disk major axis, we infer the emission height ( z ) above the midplane as a function of radius ( r ). Using this method, we measure emitting surfaces for a suite of CO isotopologues, HCN, and C 2 H. We find that 12 CO emission traces the most elevated regions with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>z</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>r</mml:mi> <mml:mo>&gt;</mml:mo> <mml:mn>0.3</mml:mn> </mml:math> , while emission from the less abundant 13 CO and C 18 O probes deeper into the disk at altitudes of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>z</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>r</mml:mi> <mml:mspace width="0.25em"/> <mml:mo>≲</mml:mo> <mml:mspace width="0.25em"/> <mml:mn>0.2</mml:mn> </mml:math> . C 2 H and HCN have lower opacities and signal-to-noise ratios, making surface fitting more difficult, and could only be reliably constrained in AS 209, HD 163296, and MWC 480, with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>z</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>r</mml:mi> <mml:mspace width="0.25em"/> <mml:mo>≲</mml:mo> <mml:mspace width="0.25em"/> <mml:mn>0.1</mml:mn> </mml:math> , i.e., relatively close to the planet-forming midplanes. We determine peak brightness temperatures of the optically thick CO isotopologues and use these to trace 2D disk temperature structures. Several CO temperature profiles and emission surfaces show dips in temperature or vertical height, some of which are associated with gaps and rings in line and/or continuum emission. These substructures may be due to local changes in CO column density, gas surface density, or gas temperatures, and detailed thermochemical models are necessary to better constrain their origins and relate the chemical compositions of elevated disk layers with those of planet-forming material in disk midplanes. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.

  DOI

• A Multifrequency ALMA Characterization of Substructures in the GM Aur Protoplanetary Disk

  The Astrophysical Journal · 2020 · 95 citations

  • Physics
  • Astrophysics
  • Astronomy

  Abstract The protoplanetary disk around the T Tauri star GM Aur was one of the first hypothesized to be in the midst of being cleared out by a forming planet. As a result, GM Aur has had an outsized influence on our understanding of disk structure and evolution. We present 1.1 and 2.1 mm ALMA continuum observations of the GM Aur disk at a resolution of ∼50 mas (∼8 au), as well as HCO + J = 3 − 2 observations at a resolution of ∼100 mas. The dust continuum shows at least three rings atop faint, extended emission. Unresolved emission is detected at the center of the disk cavity at both wavelengths, likely due to a combination of dust and free–free emission. Compared to the 1.1 mm image, the 2.1 mm image shows a more pronounced “shoulder” near R ∼ 40 au, highlighting the utility of longer-wavelength observations for characterizing disk substructures. The spectral index α features strong radial variations, with minima near the emission peaks and maxima near the gaps. While low spectral indices have often been ascribed to grain growth and dust trapping, the optical depth of GM Aur’s inner two emission rings renders their dust properties ambiguous. The gaps and outer disk ( R &gt; 100 au) are optically thin at both wavelengths. Meanwhile, the HCO + emission indicates that the gas cavity is more compact than the dust cavity traced by the millimeter continuum, similar to other disks traditionally classified as “transitional.”

  DOI

Frequent coauthors

• E. F. van Dishoeck

  147 shared

• Romane Le Gal

  Université Grenoble Alpes

  147 shared

• David J. Wilner

  144 shared

• Jane Huang

  130 shared

• Sean M. Andrews

  124 shared

• Viviana V. Guzmán

  123 shared

• Chunhua Qi

  Center for Astrophysics Harvard & Smithsonian

  111 shared

• Edwin A. Bergin

  University of Michigan–Ann Arbor

  108 shared

Education

• Ph.D., Astronomy

  Massachusetts Institute of Technology

  2009

• B.S., Physics

  Harvard University

  2004

Similar researchers at Harvard University

• Walter C Willetth-429
• JoAnn E Mansonh-359
• Randy L. Bucknerh-268
• Edward Giovannuccih-267
• Kristen Andersonh-263