Karin I. Öberg's research while affiliated with Harvard-Smithsonian Center for Astrophysics and other places

Publications (257)

Preprint
High spatial resolution observations of CO isotopologue line emission in protoplanetary disks at mid-inclinations (${\approx}$30-75{\deg}) allow us to characterize the gas structure in detail, including radial and vertical substructures, emission surface heights and their dependencies on source characteristics, and disk temperature profiles. By com...
Article
Full-text available
The chemical reservoir within protoplanetary disks has a direct impact on planetary compositions and the potential for life. A long-lived carbon- and nitrogen-rich chemistry at cold temperatures (≤ 50 K) is observed within cold and evolved planet-forming disks. This is evidenced by bright emission from small organic radicals in 1–10 Myr aged system...
Preprint
Full-text available
Understanding the initial properties of star-forming material and how they affect the star formation process is key. From an observational point of view, the feedback from young high-mass stars on future star formation properties is still poorly constrained. In the framework of the IRAM 30m ORION-B large program, we obtained observations of the tra...
Article
Full-text available
Benzonitrile ( c -C 6 H 5 CN) has been recently detected in cold and dense regions of the interstellar medium, where it has been used as a signpost of a rich aromatic organic chemistry that might lead to the production of polycyclic aromatic hydrocarbons. One possible origin of this benzonitrile is interstellar ice chemistry involving benzene ( c -...
Article
Full-text available
The distribution of molecules between the gas and solid phase during star and planet formation determines the trajectory of gas and grain surface chemistry, as well as the delivery of elements to nascent planets. This distribution is primarily set by the binding energies of different molecules to water ice surfaces. We computationally estimated the...
Preprint
The distribution of molecules between the gas and solid phase during star and planet formation, determines the trajectory of gas and grain surface chemistry, as well as the delivery of elements to nascent planets. This distribution is primarily set by the binding energies of different molecules to water ice surfaces. We computationally estimated th...
Preprint
This work presents water emission spectra at wavelengths covered by JWST (2.9-12.8 $\mu$m) as spectrally-resolved with high resolving powers (R = 30,000-100,000) using ground-based spectrographs. Two new surveys with iSHELL and VISIR are combined with previous spectra from CRIRES and TEXES to cover parts of multiple ro-vibrational and rotational ba...
Article
Full-text available
We present deep high-resolution (∼50 mas, 8 au) Atacama Large Millimeter/submillimeter Array (ALMA) 0.88 and 1.3 mm continuum observations of the LkCa 15 disk. The emission morphology shows an inner cavity and three dust rings at both wavelengths, but with slightly narrower rings at the longer wavelength. Along a faint ring at 42 au, we identify tw...
Preprint
We present deep high-resolution ($\sim$50 mas, 8 au) ALMA 0.88 and 1.3 mm continuum observations of the LkCa 15 disk. The emission morphology shows an inner cavity and three dust rings at both wavelengths, but with slightly narrower rings at the longer wavelength. Along a faint ring at 42 au, we identify two excess emission features at $\sim$10$\si...
Article
Full-text available
The ionization fraction in neutral interstellar clouds is a key physical parameter controlling multiple physical and chemical processes, and varying by orders of magnitude from the UV irradiated surface of the cloud to its cosmic-ray dominated central regions. Traditional observational tracers of the ionization fraction, which mostly rely on deuter...
Article
Full-text available
We report the discovery of a circumplanetary disk (CPD) candidate embedded in the circumstellar disk of the T Tauri star AS 209 at a radial distance of about 200 au (on-sky separation of 1.″4 from the star at a position angle of 161°), isolated via ¹³ CO J = 2−1 emission. This is the first instance of CPD detection via gaseous emission capable of t...
Article
Full-text available
HCN is among the most commonly detected molecules in star- and planet-forming regions. It is of broad interest as a tracer of star formation physics, a probe of nitrogen astrochemistry, and an ingredient in prebiotic chemical schemes. Despite this, one of the most fundamental astrochemical properties of HCN remains poorly characterized: its thermal...
Preprint
Planetary systems such as our own are formed after a long process where matter condenses from diffuse clouds to stars, planets, asteroids, comets and residual dust, undergoing dramatic changes in physical and chemical state in less than a few million years. Several studies have shown that the chemical composition during the early formation of a Sol...
Article
Full-text available
High spatial resolution CO observations of midinclination (≈30°–75°) protoplanetary disks offer an opportunity to study the vertical distribution of CO emission and temperature. The asymmetry of line emission relative to the disk major axis allows for a direct mapping of the emission height above the midplane, and for optically thick, spatially res...
Preprint
High spatial resolution CO observations of mid-inclination (30-75{\deg}) protoplanetary disks offer an opportunity to study the vertical distribution of CO emission and temperature. The asymmetry of line emission relative to the disk major axis allows for a direct mapping of the emission height above the midplane, and for optically-thick, spatially...
Article
Full-text available
The size of a disk encodes important information about its evolution. Combining new Submillimeter Array observations with archival Atacama Large Millimeter/submillimeter Array data, we analyze millimeter continuum and CO emission line sizes for a sample of 44 protoplanetary disks around stars with masses of 0.15–2 M ⊙ in several nearby star-forming...
Article
Full-text available
While protoplanetary disks are often treated as isolated systems in planet formation models, observations increasingly suggest that vigorous interactions between Class II disks and their environments are not rare. DO Tau is a T Tauri star that has previously been hypothesized to have undergone a close encounter with the HV Tau system. As part of th...
Preprint
While protoplanetary disks are often treated as isolated systems in planet formation models, observations increasingly suggest that vigorous interactions between Class II disks and their environments are not rare. DO Tau is a T Tauri star that has previously been hypothesized to have undergone a close encounter with the HV Tau system. As part of th...
Preprint
The size of a disk encodes important information about its evolution. Combining new Submillimeter Array (SMA) observations with archival Atacama Large Millimeter Array (ALMA) data, we analyze mm continuum and CO emission line sizes for a sample of 44 protoplanetary disks around stars with masses of 0.15--2\,$M_{\odot}$ in several nearby star-formin...
Article
The chemistry of phosphorus in star- and planet-forming regions is poorly understood, despite the central role of phosphorus in terrestrial biochemistry. We present Atacama Large Millimeter/submillimeter Array band 3 and 4 observations of PO and PN toward the Class I protostar B1-a, representing the first spatially resolved observations of phosphor...
Article
We report the detection of more than 120 emission lines corresponding to eight complex organic molecules (COMs; CH 3 OH, CH 3 CH 2 OH, CH 3 OCH 3 , CH 3 OCHO, CH 3 COCH 3 , NH 2 CHO, CH 2 DCN, and CH 3 CH 2 CN) and three isotopologues (CH 2 DOH, ¹³ CH 3 CN, and CH 3 C ¹⁵ N) toward the western component of the Ser-emb 11 binary young stellar object...
Article
UV photochemistry in the surface layers of protoplanetary disks dramatically alters their composition relative to previous stages of star formation. The abundance ratio CN/HCN has long been proposed to trace the UV field in various astrophysical objects; however, to date the relationship between CN, HCN, and the UV field in disks remains ambiguous....
Article
We observed HCO+ J = 1 − 0 and H13CO+ J = 1 − 0 emission toward the five protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, and MWC 480 as part of the MAPS project. HCO+ is detected and mapped at 0farcs3 resolution in all five disks, while H13CO+ is detected (S/N > 6σ) toward GM Aur and HD 163296 and tentatively detected (S/N > 3σ) towa...
Article
Sulfur-bearing molecules play an important role in prebiotic chemistry and planet habitability. They are also proposed probes of chemical ages, elemental C/O ratio, and grain chemistry processing. Commonly detected in diverse astrophysical objects, including the solar system, their distribution and chemistry remain, however, largely unknown in plan...
Article
The Molecules with ALMA at Planet-forming Scales Large Program (MAPS LP) surveyed the chemical structures of five protoplanetary disks across more than 40 different spectral lines at high angular resolution (0farcs15 and 0farcs30 beams for Bands 6 and 3, respectively) and sensitivity (spanning 0.3–1.3 mJy beam−1 and 0.4–1.9 mJy beam−1 for Bands 6 a...
Article
Constraining the distribution of gas and dust in the inner 20 au of protoplanetary disks is difficult. At the same time, this region is thought to be responsible for most planet formation, especially around the water ice line at 3–10 au. Under the assumption that the gas is in a Keplerian disk, we use the exquisite sensitivity of the Molecules with...
Article
Understanding the temperature structure of protoplanetary disks is key to interpreting observations, predicting the physical and chemical evolution of the disk, and modeling planet formation processes. In this study, we constrain the two-dimensional thermal structure of the disk around the Herbig Ae star HD 163296. Using the thermochemical code RAC...
Article
Full-text available
Small organic molecules, such as C2H, HCN, and H2CO, are tracers of the C, N, and O budget in protoplanetary disks. We present high-angular-resolution (10–50 au) observations of C2H, HCN, and H2CO lines in five protoplanetary disks from the Molecules with ALMA at Planet-forming Scales (MAPS) ALMA Large Program. We derive column density and excitati...
Article
We explore the dynamical structure of the protoplanetary disks surrounding HD 163296 and MWC 480 as part of the Molecules with ALMA at Planet-forming Scales (MAPS) large program. Using the J = 2–1 transitions of 12CO, 13CO, and C18O imaged at spatial resolutions of ∼0farcs15 and with a channel spacing of 200 m s−1, we find perturbations from Kepler...
Article
Planets form and obtain their compositions in dust- and gas-rich disks around young stars, and the outcome of this process is intimately linked to the disk chemical properties. The distributions of molecules across disks regulate the elemental compositions of planets, including C/N/O/S ratios and metallicity (O/H and C/H), as well as access to wate...
Article
Full-text available
The precursors to larger, biologically relevant molecules are detected throughout interstellar space, but determining the presence and properties of these molecules during planet formation requires observations of protoplanetary disks at high angular resolution and sensitivity. Here, we present 0.″3 observations of HC 3 N, CH 3 CN, and c -C 3 H 2 i...
Article
The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a detailed, high-resolution (∼10–20 au) view of molecular line emission in five protoplanetary disks at spatial scales relevant for planet formation. Here we present a systematic analysis of chemical substructures in 18 molecular lines toward the MAPS sources: IM Lup, GM...
Article
Deuterium fractionation is dependent on various physical and chemical parameters. Thus, the formation location and thermal history of material in the solar system is often studied by measuring its D/H ratio. This requires knowledge about the deuteration processes operating during the planet formation era. We aim to study these processes by radially...
Article
Constraining dust properties of planet-forming disks via high-angular-resolution observations is fundamental to understanding how solids are trapped in substructures and how dust growth may be favored or accelerated therein. We use ALMA dust continuum observations of the Molecules with ALMA at Planet-forming Scales (MAPS) disks and explore a large...
Article
The elemental composition of the gas and dust in a protoplanetary disk influences the compositions of the planets that form in it. We use the Molecules with ALMA at Planet-forming Scales (MAPS) data to constrain the elemental composition of the gas at the locations of potentially forming planets. The elemental abundances are inferred by comparing s...
Article
Emission substructures in gas and dust are common in protoplanetary disks. Such substructures can be linked to planet formation or planets themselves. We explore the observed gas substructures in AS 209 using thermochemical modeling with RAC2D and high-spatial-resolution data from the Molecules with ALMA at Planet-forming Scales (MAPS) program. The...
Article
During the main phase of evolution of a protoplanetary disk, accretion regulates the inner-disk properties, such as the temperature and mass distribution, and in turn, the physical conditions associated with planet formation. The driving mechanism behind accretion remains uncertain; however, one promising mechanism is the removal of a fraction of a...
Article
We report the first detection of the molecule cyanomethyl, CH 2 CN, in a protoplanetary disk. Until now, CH 2 CN had only been observed at earlier evolutionary stages, in the molecular clouds TMC-1, Sgr2, and L483, in the prestellar core L1544, and toward the protostar L1527. We detect six transitions of ortho-CH 2 CN toward the disk around nearby...
Article
The concentric gaps and rings commonly observed in protoplanetary disks in millimeter continuum emission have lent the impression that planet formation generally proceeds within orderly, isolated systems. While deep observations of spatially resolved molecular emission have been comparatively limited, they are increasingly suggesting that some disk...
Article
Here we present high-resolution (15–24 au) observations of CO isotopologue lines from the Molecules with ALMA on Planet-forming Scales (MAPS) ALMA Large Program. Our analysis employs observations of the (J = 2–1) and (1–0) lines of 13CO and C18O and the (J = 1–0) line of C17O for five protoplanetary disks. We retrieve CO gas density distributions,...
Article
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 e...
Article
Gas mass remains one of the most difficult protoplanetary disk properties to constrain. With much of the protoplanetary disk too cold for the main gas constituent, H2, to emit, alternative tracers such as dust, CO, or the H2 isotopologue HD are used. However, relying on disk mass measurements from any single tracer requires assumptions about the tr...
Preprint
Full-text available
Models of terrestrial planet formation predict that the final stages of planetary assembly, lasting tens of millions of years beyond the dispersal of young protoplanetary disks, are dominated by planetary collisions. It is through these giant impacts that planets like the young Earth grow to their final mass and achieve long-term stable orbital con...
Article
Full-text available
Models of terrestrial planet formation predict that the final stages of planetary assembly—lasting tens of millions of years beyond the dispersal of young protoplanetary disks—are dominated by planetary collisions. It is through these giant impacts that planets like the young Earth grow to their final mass and achieve long-term stable orbital confi...
Preprint
Full-text available
The disk around HD 169142 has been suggested to host multiple embedded planets due to the range of structures observed in the dust distributions. We analyze archival ALMA observations of $^{12} \mathrm{CO \ (2-1)}$, $^{13} \mathrm{CO \ (2-1)}$, and $\mathrm{C}^{18} \mathrm{O \ (2-1)}$ to search for large-scale kinematic structures associated with o...
Preprint
Full-text available
We report the first detection of the molecule cyanomethyl, CH$_2$CN, in a protoplanetary disk. Until now, CH$_2$CN had only been observed at earlier evolutionary stages, in the giant molecular clouds TMC-1 and Sgr 2, and the prestellar core L1544. We detect six transitions of ortho-CH$_2$CN towards the disk around nearby T Tauri star TW Hya. An exc...
Preprint
Full-text available
Constraining dust properties of planet-forming disks via high angular resolution observations is fundamental to understanding how solids are trapped in substructures and how dust growth may be favored or accelerated therein. We use ALMA dust continuum observations of the Molecules with ALMA at Planet-forming Scales (MAPS) disks and explore a large...
Preprint
Deuterium fractionation is dependent on various physical and chemical parameters. Thus, the formation location and thermal history of material in the solar system is often studied by measuring its D/H ratio. This requires knowledge about the deuteration processes operating during the planet formation era. We aim to study these processes by radially...
Preprint
We observed HCO$^+$ $J=1-0$ and H$^{13}$CO$^+$ $J=1-0$ emission towards the five protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, and MWC 480 as part of the MAPS project. HCO$^+$ is detected and mapped at 0.3\arcsec\,resolution in all five disks, while H$^{13}$CO$^+$ is detected (SNR$>6 \sigma$) towards GM Aur and HD 163296 and tentat...
Preprint
We explore the dynamical structure of the protoplanetary disks surrounding HD 163296 and MWC 480 as part of the Molecules with ALMA at Planet Forming Scales (MAPS) large program. Using the $J = 2-1$ transitions of $^{12}$CO, $^{13}$CO and C$^{18}$O imaged at spatial resolutions of $\sim 0.^{\prime \prime}15$ and with a channel spacing of $200$ ${\r...
Preprint
Full-text available
The elemental composition of the gas and dust in a protoplanetary disk influences the compositions of the planets that form in it. We use the Molecules with ALMA at Planet-forming Scales (MAPS) data to constrain the elemental composition of the gas at the locations of potentially forming planets. The elemental abundances are inferred by comparing s...
Preprint
The concentric gaps and rings commonly observed in protoplanetary disks in millimeter continuum emission have lent the impression that planet formation generally proceeds within orderly, isolated systems. While deep observations of spatially resolved molecular emission have been comparatively limited, they are increasingly suggesting that some disk...
Preprint
Full-text available
Gas mass remains one of the most difficult protoplanetary disk properties to constrain. With much of the protoplanetary disk too cold for the main gas constituent, H2, to emit, alternative tracers such as dust, CO, or the H2 isotopolog HD are used. However, relying on disk mass measurements from any single tracer requires assumptions about the trac...
Preprint
The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a detailed, high resolution (${\sim}$10-20 au) view of molecular line emission in five protoplanetary disks at spatial scales relevant for planet formation. Here, we present a systematic analysis of chemical substructures in 18 molecular lines toward the MAPS sources: IM...
Preprint
Full-text available
Emission substructures in gas and dust are common in protoplanetary disks. Such substructures can be linked to planet formation or planets themselves. We explore the observed gas substructures in AS 209 using thermochemical modeling with RAC2D and high-spatial resolution data from the Molecules with ALMA at Planet-forming Scales(MAPS) program. The...
Preprint
The precursors to larger, biologically-relevant molecules are detected throughout interstellar space, but determining the presence and properties of these molecules during planet formation requires observations of protoplanetary disks at high angular resolution and sensitivity. Here we present 0.3'' observations of HC$_3$N, CH$_3$CN, and $c$-C$_3$H...
Preprint
Full-text available
Here we present high resolution (15-24 au) observations of CO isotopologue lines from the Molecules with ALMA on Planet-forming Scales (MAPS) ALMA Large Program. Our analysis employs $^{13}$CO and C$^{18}$O ($J$=2-1), (1-0), and C$^{17}$O (1-0) line observations of five protoplanetary disks. We retrieve CO gas density distributions, using three ind...
Preprint
Full-text available
The Molecules with ALMA at Planet-forming Scales large program (MAPS LP) surveyed the chemical structures of five protoplanetary disks across more than 40 different spectral lines at high angular resolution (0.15" and 0.30" beams for Bands 6 and 3, respectively) and sensitivity (spanning 0.3 - 1.3 mJy/beam and 0.4 - 1.9 mJy/beam for Bands 6 and 3,...
Preprint
Sulfur-bearing molecules play an important role in prebiotic chemistry and planet habitability. They are also proposed probes of chemical ages, elemental C/O ratio, and grain chemistry processing. Commonly detected in diverse astrophysical objects, including the Solar System, their distribution and chemistry remain, however, largely unknown in plan...
Preprint
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 e...
Preprint
Full-text available
Constraining the distribution of gas and dust in the inner 20 au of protoplanetary disks is difficult. At the same time, this region is thought to be responsible for most planet formation, especially around the water ice line at 3-10 au. Under the assumption that the gas is in a Keplerian disk, we use the exquisite sensitivity of the Molecules with...
Article
To date, at least three comets—2I/Borisov, C/2016 R2 (PanSTARRS), and C/2009 P1 (Garradd)—have been observed to have unusually high CO concentrations compared to water. We attempt to explain these observations by modeling the effect of drifting solid (ice and dust) material on the ice compositions in protoplanetary disks. We find that, independent...
Article
M-stars are the most common hosts of planetary systems in the Galaxy. Protoplanetary disks around M-stars thus offer a prime opportunity to study the chemistry of planet-forming environments. We present an Atacama Large Millimeter/submillimeter Array survey of molecular line emission toward a sample of five protoplanetary disks around M4–M5 stars (...
Article
Connecting the composition of planet-forming disks with that of gas giant exoplanet atmospheres, in particular through C/O ratios, is one of the key goals of disk chemistry. Small hydrocarbons like C2H and C3H2 have been identified as tracers of C/O, as they form abundantly under high C/O conditions. We present resolved c–C3H2 observations from the...
Preprint
Full-text available
To date, at least three comets -- 2I/Borisov, C/2016 R2 (PanSTARRS), and C/2009 P1 (Garradd) -- have been observed to have unusually high CO concentrations compared to water. We attempt to explain these observations by modeling the effect of drifting solid (ice and dust) material on the ice compositions in protoplanetary disks. We find that, indepe...
Article
Massive star-forming regions exhibit an extremely rich and diverse chemistry, which in principle provides a wealth of molecular probes, as well as laboratories for interstellar prebiotic chemistry. Since the chemical structure of these sources displays substantial spatial variation among species on small scales (≲10 ⁴ au), high-angular-resolution o...
Article
In this era of Gaia and ALMA, dynamical stellar mass measurements, derived from spatially and spectrally resolved observations of the Keplerian rotation of circumstellar disks, provide benchmarks that are independent of observations of stellar characteristics and their uncertainties. These benchmarks can then be used to validate and improve stellar...
Preprint
Massive star-forming regions exhibit an extremely rich and diverse chemistry, which in principle provides a wealth of molecular probes, as well as laboratories for interstellar prebiotic chemistry. Since the chemical structure of these sources displays substantial spatial variation among species on small scales (${\lesssim}10^4$ au), high angular r...
Preprint
In this era of Gaia and ALMA, dynamical stellar mass measurements provide benchmarks that are independent of observations of stellar characteristics and their uncertainties. These benchmarks can then be used to validate and improve stellar evolutionary models, which can lead to both imprecise and inaccurate mass predictions for pre-main-sequence, l...
Article
Molecular D/H ratios are frequently used to probe the chemical past of solar system volatiles. Yet it is unclear which parts of the solar nebula hosted an active deuterium fractionation chemistry. To address this question, we present 0farcs2–0farcs4 Atacama Large Millimeter/submillimeter Array (ALMA) observations of DCO⁺ and DCN 2–1, 3–2, and 4–3 t...
Conference Paper
SPHEREx, the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and ices Explorer, is a NASA MIDEX mission planned for launch in 2024. SPHEREx will carry out the first all-sky spectral survey at wavelengths between 0.75µm and 5µm with spectral resolving power ~40 between 0.75 and 3.8µm and ~120 between 3.8 and 5µm At the end...
Article
The thermal structure of protoplanetary disks is a fundamental characteristic of the system that has wide reaching effects on disk evolution and planet formation. In this study, we constrain the 2D thermal structure of the protoplanetary disk TW Hya structure utilizing images of seven CO lines. This includes new ALMA observations of ¹²CO J=2-1 and...
Article
Formaldehyde (H₂CO) is an important precursor to organics like methanol (CH₃OH). It is important to understand the conditions that produce H₂CO and prebiotic molecules during star and planet formation. H₂CO possesses both gas-phase and solid-state formation pathways, involving either UV-produced radical precursors or CO ice and cold (≲20 K) dust gr...
Preprint
Formaldehyde (H$_2$CO) is an important precursor to organics like methanol (CH$_3$OH). It is important to understand the conditions that produce H$_2$CO and prebiotic molecules during star and planet formation. H$_2$CO possesses both gas-phase and solid-state formation pathways, involving either UV-produced radical precursors or CO ice and cold ($\...