ترغب بنشر مسار تعليمي؟ اضغط هنا

High Spatial and Spectral Resolution Observations of the Forbidden 1.707 micron Rovibronic SO Emissions on Io: Evidence for Widespread Stealth Volcanism

90   0   0.0 ( 0 )
 نشر من قبل Imke de Pater
 تاريخ النشر 2021
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

We present observations obtained with the 10-m Keck telescopes of the forbidden SO rovibronic transition at 1.707 micron on Io while in eclipse. We show its spatial distribution at a resolution of ~0.12 and a spectral resolution of R ~2500, as well as disk-integrated spectra at a high spectral resolution (R~15,000). Both the spatial distribution and the spectral shape of the SO emission band vary considerably across Io and over time. In some cases the SO emissions either in the core or the wings of the emission band can be identified with volcanoes, but the largest areas of SO emissions usually do not coincide with known volcanoes. We suggest that the emissions are caused by a large number of stealth plumes, produced through the interaction of silicate melts with superheated SO2 vapor at depth. The spectra, in particular the elevated wing of the emission band near 1.69 micron, and their spatial distribution strongly suggest the presence of non-LTE processes in addition to the direct ejection of excited SO from the (stealth and other) volcanic vents.



قيم البحث

اقرأ أيضاً

Magmatic segregation and volcanic eruptions transport tidal heat from Ios interior to its surface. Several observed eruptions appear to be extremely high temperature ($geq$ 1600 K), suggesting either very high degrees of melting, refractory source re gions, or large amounts of viscous heating on ascent. To address this ambiguity, we develop a model that couples crust and mantle dynamics to a simple compositional system. We analyse the model to investigate chemical structure and evolution. We demonstrate that magmatic segregation and volcanic eruptions lead to differentiation of the mantle, the extent of which depends on how easily high temperature melts from the more refractory lower mantle can migrate upwards. We propose that Ios highest temperature eruptions originate from this lower mantle region, and that such eruptions act to limit the degree of compositional differentiation.
We have acquired high spectral resolution observations (R=150,000) of the planetary nebulae NGC 7009 and NGC 6153, using bHROS on Gemini South. Observations of this type may provide a key to understanding why optical recombination lines (ORLs) yield systematically higher heavy element abundances for photoionized nebulae than do the classical forbidden collisionally excited lines (CELs) emitted by the same ions; NGC 7009 and NGC 6153 have notably high ORL/CEL abundance discrepancy factors (ADFs) of 5 and 10, respectively. Due to the opposite temperature dependences of ORLs and CELs, ORLs should be preferentially emitted by colder plasma. Our bHROS observations of NGC 7009 reveal that the [O III] 4363A CEL has a FWHM linewidth that is 1.5 times larger than that shown by O II ORLs in the same spectrum, despite the fact that all of these lines are emitted by the O2+ ion. The bHROS spectra of NGC 6153 also show that its O II ORLs have significantly narrower linewidths than do the [O III] 4363A and 5007A lines but, in addition, the [O III] 4363A and 5007A lines show very different velocity profiles, implying the presence of large temperature variations in the nebula.
Apart from being an important coolant, H2O is known to be a tracer of high-velocity molecular gas. Recent models predict relatively high abundances behind interstellar shockwaves. The dynamical and physical conditions of the H2O emitting gas, however , are not fully understood yet. We aim to determine the abundance and distribution of H2O, its kinematics and the physical conditions of the gas responsible for the H2O emission. The observed line profile shapes help us understand the dynamics in molecular outflows. We mapped the VLA1623 outflow, in the ground-state transitions of o-H2O, with the HIFI and PACS instruments. We also present observations of higher energy transitions of o-H2O and p-H2O obtained with HIFI and PACS towards selected outflow positions. From comparison with non-LTE radiative transfer calculations, we estimate the physical parameters of the water emitting regions. The observed water emission line profiles vary over the mapped area. Spectral features and components, tracing gas in different excitation conditions, allow us to constrain the density and temperature of the gas. The H2O emission originates in a region where temperatures are comparable to that of the warm H2 gas (Tgtrsim200K). Thus, the H2O emission traces a gas component significantly warmer than the gas responsible for the low-J CO emission. The H2O column densities at the CO peak positions are low, i.e. N(H2O) simeq (0.03-10)x10e14 cm-2. The H2O abundance with respect to H2 in the extended outflow is estimated at X(H2O)<1x10e-6, significantly lower than what would be expected from most recent shock models. The H2O emission traces a gas component moving at relatively high velocity compared to the low-J CO emitting gas. However, other dynamical quantities such as the momentum rate, energy and mechanical luminosity are estimated to be the same, independent of the molecular tracer used, CO or H2O.
Zirconium oxide(ZrO) is an important astrophysical molecule that defines the S-star classification class for cool giant stars. Accurate, empirical rovibronic energy levels, with associated labels and uncertainties, are reported for 9 low-lying electr onic states of the diatomic 90Zr16O molecule. These 8088 empirical energy levels are determined using the Marvel (Measured Active Rotational-Vibrational Energy Levels) algorithm with 23 317 input assigned transition frequencies, 22 549 of which were validated. A temperature-dependent partition function is presented alongside updated spectroscopic constants for the 9 low-lying electronic states.
Recently, Nadir and Occultation for Mars Discovery (NOMAD) ultraviolet and visible spectrometer instrument on board the European Space Agencys ExoMars Trace Gas Orbiter (TGO) simultaneously measured the limb emission intensities for both [OI] 2972 an d 5577 {AA} (green) emissions in the dayside of Martian upper atmosphere. We aim to explore the photochemistry of all these forbidden atomic oxygen emissions ([OI] 2972, 5577, 6300, 6464 {AA}) in the Martian daylight upper atmosphere and suitable conditions for the simultaneous detection of these emissions lines in the dayside visible spectra. A photochemical model is developed to study the production and loss processes of O(1S) and O(1D) by incorporating various chemical reactions of different O-bearing species in the upper atmosphere of Mars. By reducing Fox (2004) modelled neutral density profiles by a factor of 2, the calculated limb intensity profiles for [OI] 5577 and 2972 {AA} emissions are found to be consistent with the NOMAD-TGO observations. In this case, at altitudes below 120 km, our modelled limb intensity for [OI] 6300 {AA} emission is smaller by a factor 2 to 5 compared to that of NOMAD-TGO observation for [OI] 2972 {AA} emission, and above this distance it is comparable with the upper limit of the observation. We studied various parameters which can influence the limb intensities of these atomic oxygen forbidden emission lines. Our calculated limb intensity for [OI] 6300 {AA} emission, when the Mars is at near perihelion and for solar maximum condition, suggests that all these forbidden emissions should be observable in the NOMAD-TGO visible spectra taken on the dayside of Martian upper atmosphere. More simultaneous observations of forbidden atomic oxygen emission lines will help to understand the photochemical processes of oxygen-bearing species in the dayside Martian upper atmosphere.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا