Rotational spectroscopy of CH${}_3$OD with a reanalysis of CH${}_3$OD toward IRAS 16293$-$2422

Abstract

We have started a measurement campaign of numerous methanol isotopologs in low-lying torsional states in order to provide extensive line lists for radio astronomical observations from an adequate spectroscopic model and to investigate how the intricate vibration-torsion-rotation interactions manifest themselves in the spectra of different isotopic species. After CD${}_3$OH and CD${}_3$OD, we turn our focus to CH${}_3$OD, which is an important species for studying deuteration in prestellar cores and envelopes that enshroud protostars. Notably, deuteration is frequently viewed as a diagnostic tool for star formation. The measurements used in this study were obtained in two spectroscopic laboratories and cover large fractions of the 34 GHz--1.35 THz range. As done in previous studies, we employed a torsion-rotation Hamiltonian model for our analysis that is based on the rho-axis method. The resulting model describes the ground and first excited torsional states of CH${}_3$OD well up to quantum numbers $J⩽51$ and $K_a⩽18$. We derived a line list for radio astronomical observations from this model that is accurate up to at least 1.35~THz and should be sufficient for all types of radio astronomical searches for this methanol isotopolog in these two lowest torsional states. This line list was applied to a reinvestigation of CH${}_3$OD in data from the Protostellar Interferometric Line Survey of IRAS 16293--2422 obtained with the Atacama Large Millimeter/submillimeter Array. The new accurately determined value for the column density of CH${}_3$OD implies that the deuteration in methanol differs in its two functional groups by a factor of $\sim$7.5.

12 pages including figures, tables, references and appendix. Astron. Astrophys., in press

References in corpus (12)

• The ALMA Protostellar Interferometric Line Survey (PILS): First results from an unbiased submillimeter wavelength line survey of the Class 0 protostellar binary IRAS 16293-2422 with ALMA
• A Survey of CH2DOH Towards Starless and Prestellar Cores in the Taurus Molecular Cloud
• Successive deuteration in low-mass star-forming regions: the case of D${}_2$-methanol (CHD${}_2$OH) in IRAS 16293-2422
• Methanol deuteration in high-mass protostars
• Chemical Differentiation and Temperature Distribution on a Few au Scale around the Protostellar Source B335
• Rotational spectroscopy of mono-deuterated oxirane ($c$-C${}_2$H${}_3$DO) and its detection towards IRAS 16293$-$2422 B
• Rotational and rovibrational spectroscopy of CD${}_3$OH with an account of CD${}_3$OH toward IRAS 16293$-$2422
• Toward a global model of the interactions in low-lying states of methyl cyanide: rotational and rovibrational spectroscopy of the $v_4=1$ state and tentative interstellar detection of the $v_4=v_8=1$ state in Sgr B2(N)
• Rotational spectroscopy of isotopic oxirane, $c$-C${}_2$H${}_4$O
• First detection of CHD${}_2$OH towards pre-stellar cores
• On the Relationship between CH${}_3$OD Abundance and Temperature in the Orion KL Nebula
• Investigation of the rotational spectrum of CD${}_3$OD and an astronomical search toward IRAS 16293$-$2422

Cited by in corpus (2)

• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• Investigation of the rotational spectrum of CH${}_3$${}^{17}$OH and its tentative detection toward Sagittarius B2(N)