The Radio Ammonia Mid-Plane Survey (RAMPS) is a molecular line survey that aims to map a portion of the Galactic midplane in the first quadrant of the Galaxy (l = 10 • − 40 • , |b| ≤ 0.4 • ) using the Green Bank Telescope. We present results from the pilot survey, which has mapped approximately 6.5 square degrees in fields centered at l = 10 • , 23 • , 24 • , 28 • , 29 • , 30 • , 31 • , 38 • , 45 • , and 47 • . RAMPS observes the NH 3 inversion transitions NH 3 (1, 1) − (5, 5), the H 2 O 6 1,6 − 5 2,3 maser line at 22.235 GHz, and several other molecular lines. We present a representative portion of the data from the pilot survey, including NH 3 (1, 1) and NH 3 (2, 2) integrated intensity maps, H 2 O maser positions, maps of NH 3 velocity, NH 3 line width, total NH 3 column density, and NH 3 rotational temperature. These data and the data cubes from which they were produced are publicly available on the RAMPS website a .

The physical and chemical properties of cold and dense molecular clouds are key to understanding how stars form. Using the IRAM 30 m and NRO 45 m telescopes, we carried out a Multiwavelength line-Imaging survey of the 70 µm-dArk and bright clOuds (MIAO). At a linear resolution of 0.1-0.5 pc, this work presents a detailed study of pc-scale CO depletion and HCO + deuterium (D-) fractionation toward four sources (G 11.38+0.81, G 15.21-0.43, G 14.49-0.13, and G 34.74-0.12) included in our full sample. In each source with T < 20 K and n H ∼ 10 4 -10 5 cm −3 , we compared pairs of neighboring 70 µm bright and dark clumps and find that: (1) The H 2 column density and dust temperature of each source show strong spatial anti-correlation; (2) The spatial distribution of CO isotopologue lines and dense gas tracers such as 1-0 lines of H 13 CO + and DCO + are anti-correlated;(3) The abundance ratio between C 18 O and DCO + shows a strong correlation with the source temperature; (4) Both the C 18 O depletion factor and D-fraction of HCO + show robust decrease from younger clumps to more evolved clumps by a factor of more than 3; (5) Preliminary chemical modeling indicates chemical ages of our sources are ∼8 × 10 4 yr, which is comparable to their free-fall timescales and smaller than their contraction timescales, indicating that our sources are likely dynamically and chemically young.

G23.33-0.30 is a 600 M infrared dark molecular filament that exhibits large NH 3 velocity dispersions (σ ∼ 8 km s −1 ) and bright, narrow NH 3 (3,3) line emission. We have probed G23.33-0.30 at the < 0.1 pc scale and confirmed that the narrow NH 3 (3,3) line is emitted by four rare NH 3 (3,3) masers, which are excited by a large-scale shock arXiv:1910.13070v1 [astro-ph.GA] 29 Oct 2019Hogge et al.impacting the filament. G23.33-0.30 also displays a velocity gradient along its length, a velocity discontinuity across its width, shock-tracing SiO(5-4) emission extended throughout the filament, broad turbulent line widths in NH 3 (1,1) through (6,6), CS(5-4), and SiO(5-4), as well as an increased NH 3 rotational temperature (T rot ) and velocity dispersion (σ) associated with the shocked, blueshifted component. The correlations among T rot , σ, and V LSR implies that the shock is accelerating, heating, and adding turbulent energy to the filament gas. Given G23.33-0.30's location within the giant molecular cloud G23.0-0.4, we speculate that the shock and NH 3 (3,3) masers originated from the supernova remnant W41, which exhibits additional evidence of an interaction with G23.0-0.4. We have also detected the 1.3 mm dust continuum emission from at least three embedded molecular cores associated with G23.33-0.30. Although the cores have moderate gas masses (M = 7 − 10 M ), their large virial parameters (α = 4 − 9) suggest that they will not collapse to form stars. The turbulent line widths of the cores may indicate negative feedback due to the SNR shock.

Star formation primarily occurs in filaments where magnetic fields are expected to be dynamically important. The largest and densest filaments trace the spiral structure within galaxies. Over a dozen of these dense (∼104 cm−3) and long (>10 pc) filaments have been found within the Milky Way, and they are often referred to as “bones.” Until now, none of these bones has had its magnetic field resolved and mapped in its entirety. We introduce the SOFIA legacy project FIELDMAPS which has begun mapping ∼10 of these Milky Way bones using the HAWC+ instrument at 214 μm and 18.″2 resolution. Here we present a first result from this survey on the ∼60 pc long bone G47. Contrary to some studies of dense filaments in the Galactic plane, we find that the magnetic field is often not perpendicular to the spine (i.e., the center line of the bone). Fields tend to be perpendicular in the densest areas of active star formation and more parallel or random in other areas. The average field is neither parallel nor perpendicular to the Galactic plane or the bone. The magnetic field strengths along the spine typically vary from ∼20 to ∼100 μG. Magnetic fields tend to be strong enough to suppress collapse along much of the bone, but for areas that are most active in star formation, the fields are notably less able to resist gravitational collapse.

Because the 157.74 μm [C ii] line is the dominant coolant of star-forming regions, it is often used to infer the global star formation rates of galaxies. By characterizing the [C ii] and far-infrared emission from nearby Galactic star-forming molecular clumps, it is possible to determine whether extragalactic [C ii] emission arises from a large ensemble of such clumps, and whether [C ii] is indeed a robust indicator of global star formation. We describe [C ii] and far-infrared observations using the FIFI-LS instrument on the Stratospheric Observatory For Infrared Astronomy (SOFIA) airborne observatory toward four dense, high-mass, Milky Way clumps. Despite similar far-infrared luminosities, the [C ii] to far-infrared luminosity ratio, /L FIR, varies by a factor of at least 140 among these four clumps. In particular, for AGAL313.576+0.324, no [C ii] line emission is detected despite a FIR luminosity of 24,000 . AGAL313.576+0.324 lies a factor of more than 100 below the empirical correlation curve between /L FIR and found for galaxies. AGAL313.576+0.324 may be in an early evolutionary “protostellar” phase with insufficient ultraviolet flux to ionize carbon, or in a deeply embedded “‘hypercompact” region phase where dust attenuation of UV flux limits the region of ionized carbon to undetectably small volumes. Alternatively, its apparent lack of [C ii] emission may arise from deep absorption of the [C ii] line against the 158 μm continuum, or self-absorption of brighter line emission by foreground material, which might cancel or diminish any emission within the FIFI-LS instrument’s broad spectral resolution element ( km s−1).