Stringent upper limits of minor species at the cloud top of Venus: PH3, HCN, and NH3

T. Encrenaz*, T. K. Greathouse, R. Giles, T. Widemann, B. Bézard, F. Lefèvre, M. Lefèvre, W. Shao, H. Sagawa, E. Marcq, A. Arredondo

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Aims. Following several reports announcing the detection or non-detection of minor species above the clouds of Venus, we have searched for other possible signatures of PH3, HCN, and NH3 in the infrared range.

Methods. Since 2012, we have performed ground-based observations of Venus in the thermal infrared at various wavelengths to monitor the behavior of SO2 and H2O at the cloud top. We have identified spectral intervals where transitions of PH3 (around 955 cm−1), HCN (around 747 cm−1), and NH3 (around 951cm−1) are present.

Results. From the absence of any feature at these frequencies, we derive, on the disk-integrated spectrum, a 3-σ upper limit of 3 ppbv for the PH3 mixing ratio, 0.5 ppbv for HCN, and 0.3 ppbv for NH3, assuming that these species have a constant mixing ratio throughout the atmosphere. Maps of the Venus disk recorded at the center position of the lines show that there is no evidence for local detection anywhere over the Venus disk.

Conclusions. Our results bring new constraints on the maximum abundance of these species at the cloud top and in the lower mesosphere of Venus.

Original languageEnglish
Article numberA304
JournalAstronomy and Astrophysics
Volume690
Number of pages7
ISSN0004-6361
DOIs
Publication statusPublished - 2024

Keywords

  • Planets
  • Planets and satellites: atmospheres
  • Planets and satellites: composition
  • Satellites: terrestrial planets

Fingerprint

Dive into the research topics of 'Stringent upper limits of minor species at the cloud top of Venus: PH3, HCN, and NH3'. Together they form a unique fingerprint.

Cite this