Is the Sun Lighter than the Earth? Isotopic CO in the Photosphere, Viewed through the Lens of 3D Spectrum Synthesis

We consider the formation of solar infrared (2-6 micron) rovibrational bands of carbon monoxide (CO) in CO5BOLD 3D convection models, with the aim to refine abundances of the heavy isotopes of carbon (13C) and oxygen (18O,17O), to compare with direct capture measurements of solar wind light ions by the Genesis Discovery Mission. We find that previous, mainly 1D, analyses were systematically biased toward lower isotopic ratios (e.g., R23= 12C/13C), suggesting an isotopically "heavy" Sun contrary to accepted fractionation processes thought to have operated in the primitive solar nebula. The new 3D ratios for 13C and 18O are: R23= 91.4 +/- 1.3 (Rsun= 89.2); and R68= 511 +/- 10 (Rsun= 499), where the uncertainties are 1 sigma and "optimistic." We also obtained R67= 2738 +/- 118 (Rsun= 2632), but we caution that the observed 12C17O features are extremely weak. The new solar ratios for the oxygen isotopes fall between the terrestrial values and those reported by Genesis (R68= 530, R6= 2798), although including both within 2 sigma error flags, and go in the direction favoring recent theories for the oxygen isotope composition of Ca-Al inclusions (CAI) in primitive meteorites. While not a major focus of this work, we derive an oxygen abundance of 603 +/- 9 ppm (relative to hydrogen; 8.78 on the logarithmic H= 12 scale). That the Sun likely is lighter than the Earth, isotopically speaking, removes the necessity to invoke exotic fractionation processes during the early construction of the inner solar system

Preface

Arnd Wedemeyer and Christoph F. E. Holzhey, ‘Preface’, in Re-: An Errant Glossary, ed. by Christoph F. E. Holzhey and Arnd Wedemeyer, Cultural Inquiry, 15 (Berlin: ICI Berlin Press, 2019), p. vii-xv <https://doi.org/10.25620/ci-15_01

Errans:Going Astray, Being Adrift, Coming to Nothing

Today’s critical discourses and theorizing vanguards agree on the importance of getting lost, of failure, of erring — as do life coaches and business gurus. The taste for a departure from progress and other teleologies, the fascination with disorder, unfocused modes of attention, or improvisational performances cut across wide swaths of scholarly and activist discourses, practices in the arts, but also in business, warfare, and politics. Yet often the laudible failures are only those that are redeemed by subsequent successes. What could it mean to think errancy beyond such restrictions? And what would a radical critique of productivity, success, and fixed determination look like that doesn’t collapse into the infamous ‘I would prefer not to’? This volume looks for an answer in the complicated word field branching and stretching from the Latin errāre. Its contributions explore the implications of embracing error, randomness, failure, non-teleological temporalities across different disciplines, discourses, and practices, with critical attention to the ambivalences such an impossible embrace generates.‘Submit Your References’: Introduction | ARND WEDEMEYER | 1–18The Punakawans Make an Untimely Appearance: In Praise of Caves, Shadows, and Fire (or A Response to Plato’s Doctrine of Truth) | PRECIOSA DE JOYA | 19–47The Animal That Laughs at Itself: False False Alarms about the End of ‘Man’ | JAMES BURTON | 49–74Not Yet: Duration as Detour in Emmanuelle Demoris’s Mafrouza Cycle | ROSA BAROTSI | 75–92Incomplete and Self-Dismantling Structures: The Built Space, the Text, the Body | ANTONIO CASTORE | 93–112Camera Fog; or, The Pendulum of Austerity in Contemporary Portugal | MARIA JOSÉ DE ABREU | 113–40Rinko Kawauchi: Imperfect Photographs | CLARA MASNATTA | 141–58Inbuilt Errans: What Is and Is Not ‘Radical Indifference’ | ZAIRONG XIANG | 159–75Errant Counterpublics: ‘Solidarność’ and the Politics of the Weak | EWA MAJEWSKA | 177–99‘The Exile from the Law’: Keeping and Transgressing the Limits in Jewish Law | FEDERICO DAL BO | 201–31Errans: Going Astray, Being Adrift, Coming to Nothing, ed. by Christoph F. E. Holzhey and Arnd Wedemeyer, Cultural Inquiry, 24 (Berlin: ICI Berlin Press, 2022) <https://doi.org/10.37050/ci-24

Weathering:Ecologies of Exposure

Weathering is atmospheric, geological, temporal, transformative. It implies exposure to the elements and processes of wearing down, disintegration, or accrued patina. Weathering can also denote the ways in which subjects and objects resist and pass through storms and adversity. This volume contemplates weathering across many fields and disciplines; its contributions examine various surfaces, environments, scales, temporalities, and vulnerabilities. What does it mean to weather or withstand? Who or what is able to pass through safely? What is lost or gained in the process

Re-:An Errant Glossary

What’s in a prefix? How to read a prefix as short as ‘re-’? Does ‘re-’ really signify? Can it point into a specific direction? Can it reverse? Can it become the shibboleth of a ‘postcritical’ reboot? At first glance transparent and directional, ‘re-’ complicates the linear and teleological models commonly accepted as structuring the relations between past, present, and future, opening onto errant temporalities

A 3D radiative transfer framework: VII. Arbitrary velocity fields in the Eulerian frame

A solution of the radiative-transfer problem in 3D with arbitrary velocity fields in the Eulerian frame is presented. The method is implemented in our 3D radiative transfer framework and used in the PHOENIX/3D code. It is tested by comparison to our well- tested 1D co-moving frame radiative transfer code, where the treatment of a monotonic velocity field is implemented in the Lagrangian frame. The Eulerian formulation does not need much additional memory and is useable on state-of-the-art computers, even large-scale applications with 1000's of wavelength points are feasible

On The Evolution of Magnetic White Dwarfs

We present the first radiation magnetohydrodynamics simulations of the atmosphere of white dwarf stars. We demonstrate that convective energy transfer is seriously impeded by magnetic fields when the plasma-beta parameter, the thermal to magnetic pressure ratio, becomes smaller than unity. The critical field strength that inhibits convection in the photosphere of white dwarfs is in the range B = 1-50 kG, which is much smaller than the typical 1-1000 MG field strengths observed in magnetic white dwarfs, implying that these objects have radiative atmospheres. We have then employed evolutionary models to study the cooling process of high-field magnetic white dwarfs, where convection is entirely suppressed during the full evolution (B > 10 MG). We find that the inhibition of convection has no effect on cooling rates until the effective temperature (Teff) reaches a value of around 5500 K. In this regime, the standard convective sequences start to deviate from the ones without convection owing to the convective coupling between the outer layers and the degenerate reservoir of thermal energy. Since no magnetic white dwarfs are currently known at the low temperatures where this coupling significantly changes the evolution, effects of magnetism on cooling rates are not expected to be observed. This result contrasts with a recent suggestion that magnetic white dwarfs with Teff < 10,000 K cool significantly slower than non-magnetic degenerates.Comment: 11 pages, 12 figures, accepted for publication in the Astrophysical Journa

Can we trust elemental abundances derived in late-type giants with the classical 1D stellar atmosphere models?

We compare the abundances of various chemical species as derived with 3D hydrodynamical and classical 1D stellar atmosphere codes in a late-type giant characterized by T_eff=3640K, log g = 1.0, [M/H] = 0.0. For this particular set of atmospheric parameters the 3D-1D abundance differences are generally small for neutral atoms and molecules but they may reach up to 0.3-0.4 dex in case of ions. The 3D-1D differences generally become increasingly more negative at higher excitation potentials and are typically largest in the optical wavelength range. Their sign can be both positive and negative, and depends on the excitation potential and wavelength of a given spectral line. While our results obtained with this particular late-type giant model suggest that 1D stellar atmosphere models may be safe to use with neutral atoms and molecules, care should be taken if they are exploited with ions.Comment: Poster presented at the IAU Symposium 265 "Chemical Abundances in the Universe: Connecting First Stars to Planets", Rio de Janeiro, 10-14 August 2009; 2 pages, 1 figur

Unresolved fine-scale structure in solar coronal loop-tops

New and advanced space-based observing facilities continue to lower the resolution limit and detect solar coronal loops in greater detail. We continue to discover even finer substructures within coronal loop cross-sections, in order to understand the nature of the solar corona. Here, we push this lower limit further to search for the finest coronal loop substructures, through taking advantage of the resolving power of the Swedish 1 m Solar Telescope/CRisp Imaging Spectro-Polarimeter (CRISP), together with co-observations from the Solar Dynamics Observatory/Atmospheric Image Assembly (AIA). High-resolution imaging of the chromospheric Hα 656.28 nm spectral line core and wings can, under certain circumstances, allow one to deduce the topology of the local magnetic environment of the solar atmosphere where its observed. Here, we study post-flare coronal loops, which become filled with evaporated chromosphere that rapidly condenses into chromospheric clumps of plasma (detectable in Hα) known as a coronal rain, to investigate their fine-scale structure. We identify, through analysis of three data sets, large-scale catastrophic cooling in coronal loop-tops and the existence of multi-thermal, multi-stranded substructures. Many cool strands even extend fully intact from loop-top to footpoint. We discover that coronal loop fine-scale strands can appear bunched with as many as eight parallel strands within an AIA coronal loop cross-section. The strand number density versus cross-sectional width distribution, as detected by CRISP within AIA-defined coronal loops, most likely peaks at well below 100 km, and currently, 69% of the substructure strands are statistically unresolved in AIA coronal loops.Publisher PDFPeer reviewe