Spectroscopy Archives

The distribution of upper level energies Eu and Einstein-A coefficients (top left and right plots, with color-coding reflecting Eu values) across infrared wavelengths naturally traces radial temperature gradients in inner disks within and across the water snowline (bottom plot, where the spectrum is scaled to a distance of 130 pc). Adapted from Figure 1 in Blevins et al. (2016) and Figure 13 in Banzatti et al. (2023). The MIRI lines used in the analysis in Section 3 are marked with black circles. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Imaging & Spectroscopy, Status Report

JWST Reveals Excess Cool Water Near The Snowline In Compact Disks, Consistent With Pebble Drift

by Keith CowingJuly 11, 2023July 11, 2023

Previous analyses of mid-infrared water spectra from young protoplanetary disks observed with the Spitzer-IRS found an anti-correlation between water luminosity and the millimeter dust disk radius observed with ALMA.

The dependence of the 𝐼3.3 over the 𝐼6.2 (blue), 𝐼7.7 (orange), 𝐼8.6 (green), and 𝐼11.2 (red; presented in MPR23) PAH band intensities on ⟨NC⟩. The discontinuities at ∼110 ⟨NC⟩ are due to the different data sets used corresponding to different cases of PAH processing (see Section 2 and MPR23 for details.) -- astro-ph.GA

Astrochemistry, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Status Report

Polycyclic Aromatic Hydrocarbon Size Tracers

by Keith CowingJuly 9, 2023July 9, 2023

We examine the dependence of polycyclic aromatic hydrocarbon (PAH) band intensity ratios as a function of the average number of carbon atoms and assess their effectiveness as tracers for PAH […]

Pure rotational transition (J Ka′Kc′ ← J ′′ Ka′′Kc′′ = 818 ← 717) of H2CCCH+ recorded using the double resonance spectroscopic scheme. For this measurement, the IR laser frequency (red arrow) was kept fixed on resonance with the 919 ← 818 rovibrational transition within the ν1 band. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Imaging & Spectroscopy, Interstellar, Status Report

Discovery of H2CCCH+ in TMC-1

by Keith CowingJuly 6, 2023July 6, 2023

Based on a novel laboratory method, 14 mm-wave lines of the molecular ion H2CCCH+ have been measured in high resolution, and the spectroscopic constants of this asymmetric rotor determined with […]

Analysis of the R(11) region of the far-infrared spectrum of 12CH4, taken at room temperature with a mixture of nitrogen at 133 mbar (see Ref. [13]). The observed spectrum is shown in the upper part, in red and the fitted spectrum in blue. The fit residuals are presented in the lower panel. A water vapor line, included in the fit, is also identified. astro-ph.EP

Astrogeology, Icy Worlds, Imaging & Spectroscopy, Status Report, Titan

Self and N2 Collisional Broadening Of Far-infrared Methane Lines At Low-temperature With Application To Titan

by Keith CowingJuly 5, 2023July 5, 2023

We report the measurement of broadening coefficients of pure rotational lines of methane at different pressure and temperature conditions.

Astrochemistry, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Status Report

Deep Search For Glycine Conformers In Barnard 5

by Keith CowingJuly 3, 2023July 3, 2023

One of the most fundamental hypotheses in astrochemistry and astrobiology states that crucial biotic molecules like glycine (NH2CH2COOH) found in meteorites and comets are inherited from early phases of star […]

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Imaging & Spectroscopy, Interstellar, Status Report

Complex Organic Molecules In A Very Young Hot Corino, HOPS 373SW

by Keith CowingJune 29, 2023

We present the spectra of Complex Organic Molecules (COMs) detected in HOPS 373SW with the Atacama Large Millimeter/submillimeter Array (ALMA). HOPS 373SW, which is a component of a protostellar binary […]

Comparison between HST and AstroSat-measured SEDs of HIP 23309 in the FUV (1300-1700 A). Top plot shows data in linear y-scale with error bars; bottom plot is identical to top plot except with log y-scale and omission of error bars for easier viewing. The cyan and black data correspond to the unbinned HST and UVIT data, respectively. The blue points correspond to HST data degraded to the approximate quality of the AstroSat data, to enable a closer comparison. The green points correspond to the AstroSat data binned down by a factor of 5, to improve SNR and enable better visual comparison. We assumed Gaussian uncorrelated noise when rebinning the AstroSat data. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

UV Spectral Characterization of Low-Mass Stars With AstroSat UVIT for Exoplanet Applications: The Case Study of HIP 23309

by Keith CowingJune 29, 2023June 29, 2023

Characterizing rocky exoplanet atmospheres is a key goal of exoplanet science, but interpreting such observations will require understanding the stellar UV irradiation incident on the planet from its host star.

Manifestation of the scattering transparency effect in the transit spectrum of TRAPPIST-1e system having a water cloud with 𝜏=1 and 𝑍c=100 km. The transit spectrum is simulated with MC calculations for cloud particles having an 𝑟eff=20 µm. The dashed lines are the spectra obtained for constant values of 𝑔. The actual spectra, after considering the spectral variations of 𝑔, are shown in bold lines. They are obtained by interpolating among the dashed spectra. The blue curves do not consider the spectral variations of 𝜔 whereas the red curves consider the realistic variation 𝜔 for water clouds which leads to the spectral features of water droplets. Gas absorption is not considered. The spectral rise towards shorter wavelengths in the dashed curves is due to Rayleigh scattering. A color gradient for 𝑓 × 𝜔, which is a measure of scattering transparency, is shown in the background. This gradient of 𝑓 × 𝜔 is same as that shown in figure 3 for TRAPPIST-1e system. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Scattering Transparency of Clouds in Exoplanet Transit Spectra

by Keith CowingJune 27, 2023June 27, 2023

The presence of aerosols in an exoplanet atmosphere can veil the underlying material and can lead to a flat transmission spectrum during primary transit observations.

Model transmission spectrum of our canonical Hycean world K2-18 b. The model spectrum with all the molecules included is shown in grey. The spectra with the individual contributions of the different molecular species are shown as denoted in the legend. The synthetic JWST observations corresponding to the full model are shown as the gold-centered black points with error bars binned to a resolution of R= 40. The observations include one transit with NIRISS SOSS, three transits with NIRSpec G395H and two transits with MIRI LRS, as discussed in section 4. -- astro-ph.EP

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Chemical Conditions On Hycean Worlds

by Keith CowingJune 26, 2023June 26, 2023

Traditionally, the search for life on exoplanets has been predominantly focused on rocky exoplanets. Hycean worlds are a class of habitable sub-Neptunes with planet-wide oceans and H2-rich atmospheres. Their broad […]

The Orion Bar region (NIRCam image) - ESA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release

Webb Makes First Detection Of Crucial Carbon Molecule Methyl Cation (CH3+) In A Planet-forming Disc

by Keith CowingJune 26, 2023June 26, 2023

An international team of scientists have used data collected by the NASA/ESA/CSA James Webb Space Telescope to detect a molecule [1] known as the methyl cation (CH3+) for the first […]