SOFIA’s new instrument, HIRMES, will offer new capabilities for studies of some of the most pristine objects in the solar system, comets. HIRMES is unique in its ability to access water-ice bands with significant sensitivity to determine the crystalline to amorphous abundance ratio in comets, as well as the wavelength coverage to determine the dust size. Understanding the compositions of comets and related bodies in their source reservoirs will reveal the conditions by which they were formed as well as the native volatile composition of key species.
The Giant Planets in the outer solar system are composed primarily of molecular hydrogen, helium, and methane. Deuterium is an important indicator of the formation mechanism for these planets. We plan to measure HD and a thermometer, such as H2 or CH4, on all 4 Giant Planets using SOFIA/HIRMES. High spectral resolution and a broad bandpass are required. From formation models, Jupiter and Saturn are expected to exhibit the protosolar value of deuterium to hydrogen (D/H) in the Solar Nebula.
The end of the cryogenic Spitzer and Herschel missions left a lasting legacy and set the present stage for the Stratospheric Observatory For Infrared Astronomy. Since reaching full operational capability in 2014, SOFIA has taken on the mantle of being the world’s only open access resource for studies of the mid- to far-infrared universe. SOFIA’s arsenal of instruments extend beyond Spitzer’s wavelength and spectral resolution coverage, and will complement the future capabilities of JWST.
Debris disks are exoplanetary systems containing not only planets but also minor bodies, such as asteroids, comets, and Kuiper Belt Objects in our Solar System. In these systems, planets induce collisions among planets and minor bodies generating debris dust and gas. The outstanding sensitivity and spectral resolution of the High Resolution Mid Infrared Spectrograph (HIRMES) at 25-122 micron is expected to enable new studies of the kinematics and composition of the circumstellar dust and gas.
We have investigated the physical and kinematical properties of massive star forming regions at various evolutionary stages via near-infrared to centimeter observations. We first explore the initial conditions of the massive star formation by examining the properties of infrared dark clouds (IRDCs) and their natal Giant Molecular Clouds (GMCs). This study shows the observational evidences of grain growth for the first time in such extreme environments with the mid- to far-infrared data. We also show the potential importance of turbulence and magnetic field to form IRDCs.
HIRMES will provide the SOFIA community with access to many key probes of protostellar outflow and star-formation feedback. In this teletalk I'll briefly review the spectral-line emission from shocks that lie within the HIRMES grasp; the key roles this emission plays in characterizing outflows and their interactions with their surroundings; and the opportunities within our grasp with HIRMES's unprecedented combination of sensitivity and spectral resolution.
The collapse of dying massive stars results in hugely energetic supernovae (SNe), depositing enriched material into the interstellar medium and ultimately determining the evolution of the host galaxy. It is therefore crucial that we understand how massive stars evolve and die, which in turn requires accurate knowledge of the physical properties of stars just before they explode. The mass loss rates of red supergiants (RSGs) govern their evolution towards supernova and dictate the appearance of the resulting explosion.
Investigating the Early Stages of Massive Star Formation in Protocluster Environments: Multiwavelength Studies of Extended Green Objects
Massive Young Stellar Objects (MYSOs) are not found in isolation, but rather have a predilection for forming in clustered environments with other protostars. Therefore, the study of MYSOs necessarily requires the study of proto-clusters as a whole. Extended Green Objects (EGOs) are massive young protoclusters believed to be in an evolutionary state just prior to the emergence of UC HII regions - a phase which is critical for distinguishing between competing theories of massive star formation.
In addition to UV radiation, young T Tauri stars emit copious amounts of X-rays that impinge on dust during the mega-year lifetimes of protoplanetary disks. Yet, unlike UV photons, X-rays have longer penetration depths in solids and can deposit more energetic secondary electrons, potentially activating new chemical pathways in dust grains. These could lead to dust growth, and could significantly impact the primordial stages of planet formation. However, such processes remain largely unknown due to a lack of fundamental X-ray photochemical data.
The physical processes that shape the structure of the interstellar medium can be studied in detail using bright photodissociation regions (PDRs) as laboratories. The energetics and physical properties of PDRs can be determined through carbon radio recombination lines (CRRLs) and the 158 micron-[CII] line. The nimble SOFIA observatory with its upGREAT instrument produced a velocity resolved one square degree map of the Orion nebula in [CII].
SOFIA/EXES Observations of Warm H2 at High Spectral Resolution: Witnessing Para-to-Ortho Conversion Behind a Molecular Shock Wave in HH7
Spectrally-resolved observations of three pure rotational lines of H2, conducted with the EXES instrument on SOFIA toward the classic bow shock HH7, reveal systematic velocity shifts between the S(5) line of ortho-H2 and the two para-H2 lines [S(4) and S(6)] lying immediately above and below it on the rotational ladder. These shifts, which we observed for the first time, imply that we are witnessing the conversion of para-H2 to ortho-H2 within a shock wave driven by an outflow from a young stellar object.