Opacity Database (Gas-Phase)
Molecular, atomic, and aerosol opacities are a required input to any radiative transfer code. This page summarises the gas-phase opacities included in POSEIDON.
Line-by-line Cross Sections
POSEIDON v1.2 includes a comprehensive update to the opacity database to reflect recent theoretical and experimental advances:
New line lists.
Updated \(\mathrm{H_2}\) + \(\mathrm{He}\) broadening.
Improved line position accuracy for high-resolution analyses (i.e. ExoMol’s MARVEL procedure).
UV-Visible wavelength coverage (down to \(0.2 \, \mathrm{\mu m}\), where available).
Note: POSEIDON v1.4 uses the same opacity database as v1.2.
The current line-by-line opacity sources included in POSEIDON are summarised below:
Species |
Line List (Version) |
Reference |
Broadening |
Updates vs. POSEIDON 1.0 |
Plot (Click) |
|---|---|---|---|---|---|
\(\mathrm{\textbf{Common}}\) \(\mathrm{\textbf{Species}}\) |
|||||
\(\mathrm{H_2O}\) |
(2023-06-21) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
MARVELised |
|
|
\(\mathrm{CO_2}\) |
(2020-06-30) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List |
|
|
\(\mathrm{CH_4}\) |
(2024-01-13) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List |
|
|
\(\mathrm{CO}\) |
(2017-01-31) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
6 Isotopes* |
|
|
\(\mathrm{Na}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{K}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{NH_3}\) |
(2020-07-30) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
MARVELised |
|
|
\(\mathrm{HCN}\) |
(2016-12-05) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
No Change |
|
|
\(\mathrm{SO_2}\) |
(2017-01-31) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
MARVELised |
|
|
\(\mathrm{H_2 S}\) |
(2022-09-18) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{PH_3}\) |
(2017-01-31) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
No Change |
|
|
\(\mathrm{C_2 H_2}\) |
(2022-09-18) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List |
|
|
\(\mathrm{\textbf{Metal}}\) \(\mathrm{\textbf{Oxides}}\) |
|||||
\(\mathrm{TiO}\) |
(2024-05-09) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
MARVELised SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{VO}\) |
(2016-07-26) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{AlO}\) |
(2021-06-22) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
MARVELised SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{SiO}\) |
(2021-11-05) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{CaO}\) |
(2023-02-20) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{MgO}\) |
(2019-04-01) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added Species |
|
|
\(\mathrm{NaO}\) |
(2021-11-17) |
Added Species |
|
||
\(\mathrm{LaO}\) |
(2023-09-23) |
Added Species |
|
||
\(\mathrm{ZrO}\) |
(2023-07-13) |
Added Species |
|
||
\(\mathrm{SO}\) |
(2023-09-14) |
Fixed \(\gamma_L = 0.07\) \(n_L = 0.5\) |
Added Species |
|
|
\(\mathrm{NO}\) |
(2021-04-22) |
Air |
New Line List |
|
|
\(\mathrm{PO}\) |
(2017-09-10) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{\textbf{Metal}}\) \(\mathrm{\textbf{Hydrides}}\) |
|||||
\(\mathrm{TiH}\) |
(2016-07-26) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{CrH}\) |
(2016-07-26) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{FeH}\) |
(2016-07-26) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{ScH}\) |
(2016-07-26) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{AlH}\) |
(2024-03-07) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{SiH}\) |
(2017-11-01) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{BeH}\) |
(2018-02-12) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{CaH}\) |
(2022-02-11) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{MgH}\) |
(2022-02-11) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{LiH}\) |
(2016-09-27) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{NaH}\) |
(2016-09-27) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{OH}\) |
(2018-07-19) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List Air Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{OH^{+}}\) |
(2022-07-13) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added Species |
|
|
\(\mathrm{CH}\) |
(2019-02-14) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{NH}\) |
(2024-03-01) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{SH}\) |
(2019-08-01) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List Air Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{\textbf{Misc.}}\) |
|||||
\(\mathrm{OCS}\) |
(2024-04-25) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added Species |
|
|
\(\mathrm{PN}\) |
(2024-05-05) |
Semenov et al. (2024) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
New Line List SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
\(\mathrm{PS}\) |
(2017-09-10) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
SB’07 Broad to \(\mathrm{H_2}\) + \(\mathrm{He}\) |
|
|
\(\mathrm{CS}\) |
(2016-07-26) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added Species |
|
|
\(\mathrm{C_2}\) |
(2020-06-28) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added Species |
|
|
\(\mathrm{CH_3}\) |
(2019-05-01) |
Fixed \(\gamma_L = 0.05\) \(n_L = 0.5\) |
Added Species |
|
|
\(\mathrm{H_{3}^{+}}\) |
(2017-03-30) |
Fixed \(\gamma_L = 0.07\) \(n_L = 0.5\) |
No Change |
|
|
\(\mathrm{N_2 O}\) |
Air |
New Line List |
|
||
\(\mathrm{NO_2}\) |
Air |
New Line List |
|
||
\(\mathrm{\textbf{HITRAN}}\) \(\mathrm{\textbf{Line-by-line}}\) \(\mathrm{\textbf{(Low-T)}}\) |
|||||
\(\mathrm{C_2 H_4}\) |
Air |
Added Species |
|
||
\(\mathrm{C_2 H_6}\) |
Air |
Added Species |
|
||
\(\mathrm{CH_3 CN}\) |
Air |
Added Species |
|
||
\(\mathrm{CH_3 OH}\) |
Air |
Added Species |
|
||
\(\mathrm{CH_3 Cl}\) |
Air |
Added Species |
|
||
\(\mathrm{GeH_4}\) |
Air |
Added Species |
|
||
\(\mathrm{CS_2}\) |
Air |
Added Species |
|
||
\(\mathrm{O_2}\) |
Air |
New Line List |
|
||
\(\mathrm{O_3}\) |
Laboratory |
Air |
New Line List |
|
|
\(\mathrm{\textbf{HITRAN}}\) \(\mathrm{\textbf{Lab xsec}}\) \(\mathrm{\textbf{(Room T)}}\) |
|||||
\(\mathrm{DMS}\) \(\mathrm{(C_2 H_6 S)}\) |
Laboratory |
Air |
Added Species (v1.3.1) |
|
|
\(\mathrm{DMDS}\) \(\mathrm{(C_2 H_6 S_2)}\) |
Laboratory |
Air |
Added Species (v1.3.1) |
|
|
\(\mathrm{C H_3 S H}\) |
Laboratory |
Air |
Added Species (v1.3.1) |
|
|
\(\mathrm{C_3 H_4}\) |
Laboratory |
Air |
Added Species (v1.3.1) |
|
|
\(\mathrm{\textbf{Atoms}}\) \(\mathrm{\textbf{and Ions}}\) |
|||||
\(\mathrm{Al}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added Species |
|
||
\(\mathrm{Ba}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added Species |
|
||
\(\mathrm{Ba^{+}}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added Species |
|
||
\(\mathrm{Ca}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Ca^{+}}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Cr}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added Species |
|
||
\(\mathrm{Cs}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Fe}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Fe^{+}}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Li}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Mg}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Mg^{+}}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Mn}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Ni}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added species |
|
||
\(\mathrm{O}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added species |
|
||
\(\mathrm{Rb}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Sc}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Added species |
|
||
\(\mathrm{Ti}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{Ti^{+}}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{V}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
||
\(\mathrm{V^{+}}\) |
\(\mathrm{H_2}\) + \(\mathrm{He}\) |
Air Wave. to Vacuum |
|
* For CO, POSEIDON defaults to a weighted average using terrestrial isotope ratios. Users can also treat each CO isotopologue as separate species (e.g. 12C-16O, 13C-16O, 12C-17O, etc.) for modelling and retrieval purposes. All other chemical species use cross sections for the principal isotopologue only.
\(\mathrm{H_2 + He}\) broadening data are mostly sourced from ExoMol’s H2.broad and He.broad files and we include the J dependence (a0). Where these data are not available, we use the estimated \(\mathrm{H_2 + He}\) pressure broadening parameters from Chubb et al. (2022).
The continuum opacity sources, including collision-induced absorption (CIA) and Rayleigh scattering cross sections, are unchanged from POSEIDON v1.0.
A description of the original public release POSEIDON opacity database can be found in MacDonald & Lewis (2022) (Appendix C).
Is your favourite molecule missing? Has a revolutionary new line list just been released? Please address any request for new opacities to: Ryan.MacDonald@st-andrews.ac.uk.