A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk.

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula.

Binarity of a protostar affects the evolution of the disk and planets.

Nearly half of all stars similar to our Sun are in binary or multiple systems, which may affect the evolution of the stars and their protoplanetary disks during their earliest stages. NGC 1333-IRAS2A is a young, Class 0, low-mass protostellar system located in the Perseus molecular cloud. It is known to drive two bipolar outflows that are almost perpendicular to each other on the sky and is resolved into binary components, VLA1 and VLA2, through long wavelength continuum observations.

Early volatile depletion on planetesimals inferred from C-S systematics of iron meteorite parent bodies.

During the formation of terrestrial planets, volatile loss may occur through nebular processing, planetesimal differentiation, and planetary accretion. We investigate iron meteorites as an archive of volatile loss during planetesimal processing. The carbon contents of the parent bodies of magmatic iron meteorites are reconstructed by thermodynamic modeling.

Meridional flows in the disk around a young star.

Protoplanetary disks are known to possess a variety of substructures in the distribution of their millimetre-sized grains, predominantly seen as rings and gaps, which are frequently interpreted as arising from the shepherding of large grains by either hidden, still-forming planets within the disk or (magneto-)hydrodynamic instabilities. The velocity structure of the gas offers a unique probe of both the underlying mechanisms driving the evolution of the disk-such as movement of planet-building material from volatile-rich regions to the chemically inert midplane-and the details of the required removal of angular momentum. Here we report radial profiles of the three velocity components of gas in the upper layers of the disk of the young star HD 163296, as traced by emission from CO molecules.

EXPLORING THE ORIGINS OF DEUTERIUM ENRICHMENTS IN SOLAR NEBULAR ORGANICS.

Deuterium-to-hydrogen (D/H) enrichments in molecular species provide clues about their original formation environment. The organic materials in primitive solar system bodies generally have higher D/H ratios and show greater D/H variation when compared to D/H in solar system water. We propose this difference arises at least in part due to (1) the availability of additional chemical fractionation pathways for organics beyond that for water, and (2) the higher volatility of key carbon reservoirs compared to oxygen.

Tracing the ingredients for a habitable earth from interstellar space through planet formation.

We use the C/N ratio as a monitor of the delivery of key ingredients of life to nascent terrestrial worlds. Total elemental C and N contents, and their ratio, are examined for the interstellar medium, comets, chondritic meteorites, and terrestrial planets; we include an updated estimate for the bulk silicate Earth (C/N = 49.0 ± 9.

The ancient heritage of water ice in the solar system.

Identifying the source of Earth's water is central to understanding the origins of life-fostering environments and to assessing the prevalence of such environments in space. Water throughout the solar system exhibits deuterium-to-hydrogen enrichments, a fossil relic of low-temperature, ion-derived chemistry within either (i) the parent molecular cloud or (ii) the solar nebula protoplanetary disk. Using a comprehensive treatment of disk ionization, we find that ion-driven deuterium pathways are inefficient, which curtails the disk's deuterated water formation and its viability as the sole source for the solar system's water.

Ortho/para ratio of H2O+ toward Sagittarius B2(M) revisited.

The HIFI instrument aboard the Herschel satellite has allowed the observation and characterization of light hydrides, the building blocks of interstellar chemistry. In this article, we revisit the ortho/para ratio for H2O(+) toward the Sgr B2(M) cloud core. The line of sight toward this star forming region passes through several spiral arms and the gas in the Bar potential in the inner Galaxy.

Ortho-to-para ratio in interstellar water on the sightline toward Sagittarius B2(N).

The determination of the water ortho-to-para ratio (OPR) is of great interest for studies of the formation and thermal history of water ices in the interstellar medium and protoplanetary disk environments. We present new Herschel observations of the fundamental rotational transitions of ortho- and para-water on the sightline toward Sagittarius B2(N), which allow improved estimates of the measurement uncertainties due to instrumental effects and assumptions about the excitation of water molecules. These new measurements, suggesting a spin temperature of 24-32 K, confirm the earlier findings of an OPR below the high-temperature value on the nearby sightline toward Sagittarius B2(M).

An old disk still capable of forming a planetary system.

From the masses of the planets orbiting the Sun, and the abundance of elements relative to hydrogen, it is estimated that when the Solar System formed, the circumstellar disk must have had a minimum mass of around 0.01 solar masses within about 100 astronomical units of the star. (One astronomical unit is the Earth-Sun distance.

Hot, metastable hydronium ion in the Galactic centre: formation pumping in X-ray-irradiated gas?

With a 3.5 m diameter telescope passively cooled to approximately 80 K, and a science payload comprising two direct detection cameras/medium resolution imaging spectrometers (PACS and SPIRE) and a very high spectral resolution heterodyne spectrometer (HIFI), the Herschel Space Observatory is providing extraordinary observational opportunities in the 55-670 μm spectral range. HIFI has opened for the first time to high-resolution spectroscopy the submillimetre band that includes the fundamental rotational transitions of interstellar hydrides, the basic building blocks of astrochemistry.

Water in star- and planet-forming regions.

In this paper, we discuss the astronomical search for water vapour in order to understand the disposition of water in all its phases throughout the processes of star and planet formation. Our ability to detect and study water vapour has recently received a tremendous boost with the successful launch and operation of the Herschel Space Observatory. Herschel spectroscopic detections of numerous transitions in a variety of astronomical objects, along with previous work by other space-based observatories, will be threaded throughout this paper.

Detection of the water reservoir in a forming planetary system.

Icy bodies may have delivered the oceans to the early Earth, yet little is known about water in the ice-dominated regions of extrasolar planet-forming disks. The Heterodyne Instrument for the Far-Infrared on board the Herschel Space Observatory has detected emission lines from both spin isomers of cold water vapor from the disk around the young star TW Hydrae. This water vapor likely originates from ice-coated solids near the disk surface, hinting at a water ice reservoir equivalent to several thousand Earth oceans in mass.

Ocean-like water in the Jupiter-family comet 103P/Hartley 2.

For decades, the source of Earth's volatiles, especially water with a deuterium-to-hydrogen ratio (D/H) of (1.558 ± 0.001) × 10(-4), has been a subject of debate.