11:30 〜 11:45
[PPS04-14] Ground-based observations of the Venusian O2 airglow emission using WINERED
キーワード：金星上層大気、酸素分子大気光、地上観測、分光
One of the various research questions regarding the Venusian atmosphere is to understand the details of the temperature field and atmospheric circulation in the upper atmosphere. Although it is thought that atmospheric waves excited at the cloud layer propagate upward and deposit angular momentum where they break, observational information that can constrain such a meteorological process is still insufficient. With regard to the temperature distribution, there is a variation of several tens of Kelvins at altitudes above 85 km in the results measured by Venus Express instruments and ground-based observations [e.g., Limaye et al., 2017]. This disagreement remains to be discussed whether it is indicative of actual temperature variability or whether it includes systematic biases from one instrument to another. The first and foremost challenge is to increase the number of more observational data in the future.
To address this issue, we focus on the oxygen (O2) airglow emission emitted at an altitude of around 95 km in the Venusian atmosphere and derive the O2 rotational temperature from its high-dispersion spectra to constrain the temperature field in this altitude region. Although observations of Venusian O2 airglow itself have been conducted for many years [e.g., Connes et al., 1979; Crisp et al., 1996; Ohtsuki et al., 2008; Krasnopolsky 2010; Gerad et al., 2017], most of the previous studies analyzed the spatial distribution of the emission intensity using spectrometers with relatively low/moderate spectral resolutions. There are only a limited number of studies in which the rotational temperature was derived with high-dispersion spectroscopy. Most of them were conducted with spectrometers at that time, which had a narrow instantaneous spectral coverage, and only a few lines of O2 airglow were acquired simultaneously.
A new and sensitive Venusian O2 airglow observation became a reality with the recent installation of a new instrument, named WINERED, on the Magellan Clay 6.5-m telescope in the Las Campanas Observatory, Chile. WINERED [Ikeda et al., 2022] is a cross-dispersed echelle spectrograph with a very high throughput. It achieves high spectral resolution (resolving power of 28,000 or 70,000) with a sufficiently wide instantaneous wavelength coverage that captures the entire O2 emission lines at the 1.27-micron band. This should significantly improve the precision of the rotational temperature derivation. Needless to say, the high spatial resolution of the Magellan telescope and the high sensitivity of WINERED are beneficial for mapping the O2 rotational temperature.
To assess the performance of Magellan/WINERED for Venusian O2 observations with the aim of realizing long-term continuous observations in the future, we piloted Venus observations in June and November 2023 when Venus was in favorable positions for the airglow observation. As a result, it was confirmed that spectra of O2 airglow emission can be obtained with sufficient quality for scientific analysis, although stray light contaminations from the dayside of Venus exist. This talk will discuss the results of these initial observations and our plan for future continued observations.
To address this issue, we focus on the oxygen (O2) airglow emission emitted at an altitude of around 95 km in the Venusian atmosphere and derive the O2 rotational temperature from its high-dispersion spectra to constrain the temperature field in this altitude region. Although observations of Venusian O2 airglow itself have been conducted for many years [e.g., Connes et al., 1979; Crisp et al., 1996; Ohtsuki et al., 2008; Krasnopolsky 2010; Gerad et al., 2017], most of the previous studies analyzed the spatial distribution of the emission intensity using spectrometers with relatively low/moderate spectral resolutions. There are only a limited number of studies in which the rotational temperature was derived with high-dispersion spectroscopy. Most of them were conducted with spectrometers at that time, which had a narrow instantaneous spectral coverage, and only a few lines of O2 airglow were acquired simultaneously.
A new and sensitive Venusian O2 airglow observation became a reality with the recent installation of a new instrument, named WINERED, on the Magellan Clay 6.5-m telescope in the Las Campanas Observatory, Chile. WINERED [Ikeda et al., 2022] is a cross-dispersed echelle spectrograph with a very high throughput. It achieves high spectral resolution (resolving power of 28,000 or 70,000) with a sufficiently wide instantaneous wavelength coverage that captures the entire O2 emission lines at the 1.27-micron band. This should significantly improve the precision of the rotational temperature derivation. Needless to say, the high spatial resolution of the Magellan telescope and the high sensitivity of WINERED are beneficial for mapping the O2 rotational temperature.
To assess the performance of Magellan/WINERED for Venusian O2 observations with the aim of realizing long-term continuous observations in the future, we piloted Venus observations in June and November 2023 when Venus was in favorable positions for the airglow observation. As a result, it was confirmed that spectra of O2 airglow emission can be obtained with sufficient quality for scientific analysis, although stray light contaminations from the dayside of Venus exist. This talk will discuss the results of these initial observations and our plan for future continued observations.