Waves in Pluto’s Upper Atmosphere
نویسندگان
چکیده
Observations of the 2007 March 18 occultation of the star P445.3 (2UCAC 25823784; R = 15.3) by Pluto were obtained at high time resolution at five sites across the western United States and reduced to produce light curves for each station using standard aperture photometry. Global models of Pluto’s upper atmosphere are fitted simultaneously to all resulting light curves. The results of these model fits indicate that the structure of Pluto’s upper atmosphere is essentially unchanged since the previous occultation observed in 2006, leading to a well-constrained measurement of the atmospheric half-light radius at 1291 ± 5 km. These results also confirm that the significant increase in atmospheric pressure detected between 1988 and 2002 has ceased. Inversion of the Multiple Mirror Telescope Observatory light curves with unprecedented signal-to-noise ratios reveals significant oscillations in the number density, pressure, and temperature profiles of Pluto’s atmosphere. Detailed analysis of this highest resolution light curve indicates that these variations in Pluto’s upper atmospheric structure exhibit a previously unseen oscillatory structure with strong correlations of features among locations separated by almost 1200 km in Pluto’s atmosphere. Thus, we conclude that these variations are caused by some form of large-scale atmospheric waves. Interpreting these oscillations as Rossby (planetary) waves allows us to establish an upper limit of less than 3 m s−1 for horizontal wind speeds in the sampled region (radius 1340–1460 km) of Pluto’s upper atmosphere.
منابع مشابه
Long-wavelength Density Fluctuations Resolved in Pluto’s High Atmosphere
Near-infrared measurements of the occultation of star P445.3 by Pluto on 2007 March 18 reveal that Pluto’s upper atmosphere (∼200–400 km altitude) is unexpectedly dynamic. At a wavelength of 1.6 μm, numerous vertical fluctuations (8–20 km) of density are detected with unprecedented signal-to-noise ratio. These fluctuations are achromatic, nearly limb-aligned, and fully resolved along a ∼1000 km...
متن کاملObservations of a successive stellar occultation by Charon and graze by Pluto in 2011
Introduction: Since the late 1980s, stellar occultations have provided snapshots of the Pluto system and specifically of Pluto’s atmospheric evolution. The lower atmosphere, below roughly half-light level in an occultation light curve, has changed distinctly over time (e.g. [1, 2]). Theorized explanations for the lower atmospheric structure include a steep thermal gradient and/or extinction, th...
متن کاملPluto’s lower atmosphere structure and methane abundance from high-resolution spectroscopy and stellar occultations
Context. Pluto possesses a thin atmosphere, primarily composed of nitrogen, in which the detection of methane has been reported. Aims. The goal is to constrain essential but so far unknown parameters of Pluto’s atmosphere such as the surface pressure, lower atmosphere thermal stucture, and methane mixing ratio. Methods. We use high-resolution spectroscopic observations of gaseous methane, and a...
متن کاملNOTE: Detection of Gaseous Methane on Pluto
0.5% CO, 1.5% CH4 (by mass), and N2 in an intimate mixture (Owen et al. 1993). Assuming the N2–CO–CH4 frost acts like an ideal mixture, We obtained Pluto’s spectrum using the CSHELL echelle one finds that XCH4 is only 0.0001% to 0.001%. However, Lellouch (1994) spectrograph at NASA’s IRTF on Mauna Kea, on 25–26 May points out that Triton’s XCH4 is several hundred times greater than that 1992, w...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2008