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We present velocity resolved SOFIA/upGREAT observations of [OI] and [CII] lines toward a Class I protostar, L1551 IRS 5, and its outflows. The SOFIA observations detect [OI] emission toward only the protostar and [CII] emission toward the protostar and the red-shifted outflow. The [OI] emission has a width of $\sim$100 km s$^{-1}$ only in the blue-shifted velocity, suggesting an origin in shocked gas. The [CII] lines are narrow, consistent with an origin in a photodissociation region. Differential dust extinction from the envelope due to the inclination of the outflows is the most likely cause of the missing red-shifted [OI] emission. Fitting the [OI] line profile with two Gaussian components, we find one component at the source velocity with a width of $\sim$20 km s$^{-1}$ and another extremely broad component at -30 km s$^{-1}$ with a width of 87.5 km s$^{-1}$, the latter of which has not been seen in L1551 IRS 5. The kinematics of these two components resemble cavity shocks in molecular outflows and spot shocks in jets. Radiative transfer calculations of the [OI], high-J CO, and H$_2$O lines in the cavity shocks indicate that [OI] dominates the oxygen budget, making up more than 70% of the total gaseous oxygen abundance and suggesting [O]/[H] of $\sim$1.5$\times$10$^{-4}$. Attributing the extremely broad [OI] component to atomic winds, we estimate the intrinsic mass loss rate of (1.3$\pm$0.8)$\times$ 10$^{-6}$ M$_{\odot}$ yr$^{-1}$. The intrinsic mass loss rates derived from low-J CO, [OI], and HI are similar, supporting the model of momentum-conserving outflows, where the atomic wind carries most momentum and drives the molecular outflows., 19 pages, 14 figures, accepted for publication in The Astrophysical Journal

We report the detection of four new hot corino sources, G211.47-19.27S, G208.68-19.20N1, G210.49-19.79W and G192.12-11.10 from a survey study of Planck Galactic Cold Clumps in the Orion Molecular Cloud Complex with the Atacama Compact Array (ACA). Three sources had been identified as low mass Class 0 protostars in the Herschel Orion Protostar Survey (HOPS). One source in the lambda Orionis region is firstly reported as a protostellar core. We have observed abundant complex organic molecules (COMs), primarily methanol but also other oxygen-bearing COMs (in G211.47-19.27S and G208.68-19.20N1) and the molecule of prebiotic interest NH2CHO (in G211.47-19.27S), signifying the presence of hot corinos. While our spatial resolution is not sufficient for resolving most of the molecular emission structure, the large linewidth and high rotational temperature of COMs suggest that they likely reside in the hotter and innermost region immediately surrounding the protostar. In G211.47-19.27S, the D/H ratio of methanol ([CH2DOH]/[CH3OH]) and the 12C/13C ratio of methanol ([CH3OH]/[13CH3OH]) are comparable to those of other hot corinos. Hydrocarbons and long carbon-chain molecules such as c-C3H2 and HCCCN are also detected in the four sources, likely tracing the outer and cooler molecular envelopes., 37 pages, 51 figures, to be published in ApJ

We present results from a comprehensive submillimeter spectral survey toward the source Orion South, based on data obtained with the Heterodyne Instrument for the Far-Infrared instrument on board the Herschel Space Observatory, covering the frequency range of 480 to 1900 GHz. We detect 685 spectral lines with signal-to-noise ratios (S/Ns) > 3 sigma, originating from 52 different molecular and atomic species. We model each of the detected species assuming conditions of Local Thermodynamic Equilibrium. This analysis provides an estimate of the physical conditions of Orion South (column density, temperature, source size, and VLSR). We find evidence for three different cloud components: a cool (T-ex similar to 20-40 K), spatially extended (> 60 ''), and quiescent (Delta V-FWHM similar to 4 km s(-1)) component; a warmer (T-ex similar to 80-100 K), less spatially extended (similar to 30 ''), and dynamic (Delta V-FWHM similar to 8 km s(-1)) component, which is likely affected by embedded outflows; and a kinematically distinct region (T-ex > 100 K; V-LSR similar to 8 km s(-1)), dominated by emission from species that trace ultraviolet irradiation, likely at the surface of the cloud. We find little evidence for the existence of a chemically distinct "hot-core" component, likely due to the small filling factor of the hot core or hot cores within the Herschel beam. We find that the chemical composition of the gas in the cooler, quiescent component of Orion South more closely resembles that of the quiescent ridge in Orion-KL. The gas in the warmer, dynamic component, however, more closely resembles that of the Compact Ridge and Plateau regions of Orion-KL, suggesting that higher temperatures and shocks also have an influence on the overall chemistry of Orion South.

While warm dense gas is prevalent around low-mass protostars, the presence of complex saturated molecules-the chemical inventory characteristic of hot cores-has remained elusive in such environments. Here we report the results of an IRAM 30 m study of the molecular composition associated with the low-mass protostar IRAS 16293-2422. Our observations highlight an extremely rich organic inventory in this source with abundant amounts of complex O- and N-bearing molecules such as formic acid, HCOOH, acetaldehyde, CH3CHO, methyl formate, CH3OCHO, dimethyl ether, CH3OCH3, acetic acid, CH3COOH, methyl cyanide, CH3CN, ethyl cyanide, C2H5CN, and propyne, CH3CCH. We compare the composition of the hot core around this low-mass young stellar object with those around massive protostars and address the chemical processes involved in molecular complexity in regions of star formation.

A compilation of the available spectroscopic millimeter- and submillimeter-wave data of the ground and first excited states of C-13(1)-methyl formate ((HCOOCH3)-C-13) has been carried out. The exhaustive analysis of the available transition lines of (HCOOCH3)-C-13 has led to the assignment of 7457 spectral lines by means of a global fit of 45 parameters, using the Rho-Axis Method and the BELGI-Cs code, with a resulting unitless standard deviation of 0.57. Over 1600 lines are included for the first time in the fit. In addition, the line strengths of spectral lines are also calculated using the most recent experimental measurement of the electric dipole moment. In conclusion, the present study represents a notable improvement with respect to previous (HCOOCH3)-C-13 spectral analyses. Therefore, the better accuracy of the present analysis may help the future identification of new (HCOOCH3)-C-13 lines in the interstellar and circumstellar media, and may contribute to decrease some of the spectral confusion due to these species in astronomical surveys.

Water is a crucial molecule in molecular astrophysics as it controls much of the gas/grain chemistry, including the formation and evolution of more complex organic molecules in ices. Pre-stellar cores provide the original reservoir of material from which future planetary systems are built, but few observational constraints exist on the formation of water and its partitioning between gas and ice in the densest cores. Thanks to the high sensitivity of the Herschel Space Observatory, we report on the first detection of water vapor at high spectral resolution toward a dense cloud on the verge of star formation, the pre-stellar core L1544. The line shows an inverse P-Cygni profile, characteristic of gravitational contraction. To reproduce the observations, water vapor has to be present in the cold and dense central few thousand AU of L1544, where species heavier than Helium are expected to freeze-out onto dust grains, and the ortho:para H2 ratio has to be around 1:1 or larger. The observed amount of water vapor within the core (about 1.5x10^{-6} Msun) can be maintained by Far-UV photons locally produced by the impact of galactic cosmic rays with H2 molecules. Such FUV photons irradiate the icy mantles, liberating water wapor in the core center. Our Herschel data, combined with radiative transfer and chemical/dynamical models, shed light on the interplay between gas and solids in dense interstellar clouds and provide the first measurement of the water vapor abundance profile across the parent cloud of a future solar-type star and its potential planetary system., Comment: The Astrophysical Journal Letters, in press