Measuring Dust Attenuation Curves of SINGS/KINGFISH Galaxies Using Swift/UVOT Photometry

We present Swift/Ultraviolet Optical Telescope (UVOT) integrated light photometry of the Spitzer Infrared Nearby Galaxies Survey (SINGS) and the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel (KINGFISH) samples of nearby galaxies. Combining the Swift/UVOT data with archival photometry, we investigate a variety of dust attenuation curves derived using MCSED, a flexible spectral energy distribution fitting code. We fit the panchromatic data using three different star formation history (SFH) parameterizations: a decaying exponential, a double power law, and a piecewise function with breaks at physically motivated ages. We find that the average attenuation law of the sample changes slightly based on the SFH assumed. Specifically, the exponential SFH leads to the shallowest attenuation curves. Using simulated data, we also find the exponential SFH fails to outperform the more complex SFHs. Finally, we find a systematic offset in the derived bump strength between SED fits with and without UVOT data, where the inclusion of UVOT data leads to smaller bump strengths, highlighting the importance of the UVOT data. This discrepancy is not seen in fits to mock photometry. Understanding dust attenuation in the local universe is key to understanding high redshift objects where rest-frame far-infrared data is unavailable.Comment: 30 pages, 13 figures, accepted for publication in Ap

JINGLE – IV. Dust, H I gas and metal scaling laws in the local Universe

Scaling laws of dust, Hi gas and metal mass with stellar mass, specific star formation rate and metallicity are crucial to our understanding of the buildup of galaxies through their enrichment with metals and dust. In this work, we analyse how the dust and metal content varies with specific gas mass (MHI/M?) across a diverse sample of 423 nearby galaxies. The observed trends are interpreted with a set of Dust and Element evolUtion modelS (DEUS) – including stellar dust production, grain growth, and dust destruction – within a Bayesian framework to enable a rigorous search of the multi-dimensional parameter space. We find that these scaling laws for galaxies with −1.0 . logMHI/M? . 0 can be reproduced using closed-box models with high fractions (37-89%) of supernova dust surviving a reverse shock, relatively low grain growth efficiencies (=30-40), and long dust lifetimes (1-2Gyr). The models have present-day dust masses with similar contributions from stellar sources (50-80%) and grain growth (20-50%). Over the entire lifetime of these galaxies, the contribution from stardust (>90%) outweighs the fraction of dust grown in the interstellar medium (<10%). Our results provide an alternative for the chemical evolution models that require extremely low supernova dust production efficiencies and short grain growth timescales to reproduce local scaling laws, and could help solving the conundrum on whether or not grains can grow efficiently in the interstellar medium

Glacier discharge in the Sor-Rondane, a contribution to the mass balance of Dronning Maud Land, Antarctica

Mass transport and mass flux values for the different types of glaciers in the Sor-Rondane are calculated from computer models, based upon gravity data and geodetic stake velocity measurements. The results are interpreted in the light of a general flow line analysis, glacial geological investigations and of the ablation terms of the mass balance for Dronning Maud Land and Antarctica

Glaciation of the central part of the Soer Rondane, Antarctica: glaciological evidence

Ice thickness measurements, carried out by radio echo sounder and gravimeter in the central part of the Sor Rondane Mountains, reveal a subglacial topography of the outlet glaciers and itstributaries characterized by U-shaped valley profiles and overdeepened bedrock. Mass-flux measurements highlight the reduced flow of at least one glacier (Jenningsbreen). This glacier isin the process of being cut off from the main ice supply and may serve as an example for the deglaciation process. An interesting feature of this deglaciation is that, once decoupled from themain ice supply, this glacier is probably characterized by an increased lowering of the ice surface gradient due to the ablation which is characteristic for the upper part of the present outletglacier. In the end this will result in a southward flow of which examples can be found elsewhere in the mountains. On the basis of the field evidence a numerical flow line model ispresented to simulate the behaviour of the outlet glaciers of the central part of the mountains during the last glacial maximum. These experiments show an increase of 300-400 m in icethickness under realistic assumptions for mass balance, temperature and sea level. Some of the higher glacial levels are then attributed to an environment characterized by a higheraccumulation predating the last glacial maximum

Modelling glacier fluctuations in the Soer Rondane, Dronning Maud Land, Antarctica

Morainic deposits found above the present glacier surface in the central Sor Rondane Mountains give evidence of former glaciations. In this paper, an attemptis made to interprete these observed glacier fluctuations in terms of environmental change. To do this, a numerical flowline model, taking into accountthermodynamics and a coupled ice shelf, has been developed and is applied to two outlet glaciers through the mountain range, Gunnestadbreen andJenningsbreen. It is found that lower ice temperatures accompagned by a reduced accumulation, further enhanced by a drop in sea level corresponding totypical glacial conditions account for a 150 - 200 m rise in glacier level. From a comparison of these results with palaeogeographical reconstruction for a'maximum' glacial stage for Jenningsbreen by Hirakawa et al. (1989) it is argued that their morainic deposits relate to an earlier Cenozoic glaciation involvinga full grown ice sheet

Report of the glaciological field party in the Soer Rondane Mountains region, 1989-1990 Summer Season (JARE-31)

Summer party of the 31st Japanese Antarctic Research Experdition (JARE-31) carried out maintenance of automatic meteorological stations, glaciological observation, and drilling test for"Antarctic Climate Research (ACR)" project from late December 1989 to January 1990 around the Soer Rondane Mountains region. This party is constituted by four glaciologists includingtwo Belgian observers and one JARE-30 member.Three prototypes of electromechanical ice drill for deep core sampling using antifreezing liquid were successfully tested on a bare glacier at Jenningsbreen. On the same glacier, dynamicsof glacier movement were studied by Belgian observers. Mass balance measurement were conducted on Goosenbreen of Brattnipane.Two helicopters were employed for geological and topographical survey in the Soer Rondane region, so that we were able to fly to Nansenisen, south of Soer Rondane, and to obtainsurface bare ice within dust band (volcanic ash?)

Numerical modeling of Glacier d'Argentiere and its historic front variations

A numerical glacier model has been developed for Glacier d'Argentiere (France) in order to study its relation with climate and investigate possible causes forthe observed variations in the terminus record since the beginning of the Little Ice Age. At first results are presented from a basic sensitivity investigation,with plots of steady state glacier length versus perturbations in mass balance and glacier reaction with respect to sinusoidal net balance oscillations. An attemptis then made to simulate the historic front variations. The mass balance history of the glacier is constructed assuming a linear relationship with (i) summertemperature anomalies and (ii) mean annual temperature anomalies for Basel dating back to the beginning of the 16th century. Although model run (ii) turnsout to yield better agreement with the observations, both simulations have in common that the observed glacier retreat comes too late. Improved simulationscan only be obtained assuming an additional negative mass balance perturbation of around 0.1 m/year over roughly the last 150 years. These results indicatethat the assumption of a linear relationship between summer temperature and the glacier's mass balance may not be valid anymore when extrapolated to pastenvironments. This might be evidence of additional micrometeorological and glacier surface conditions prevailing in valleys at maximum glacier extent, thatare not absorbed well in the climatic records

Dynamics of the Antarctic ice cap: I. Ice thickness measurements related to the damming effect of the Sør Rondane, Dronning Maud Land, Antarctica

Preliminary results of the 1986-87 Belgian Participation in the JARE 28 Expedition to the Sør Rondane, Antarctica, are presented. The principles of ice thickness calculations, based on gravity measurements, are given. The subglacial results illustrate the damming effect of a coastal mountain range and indicate an ice covered landscape in the process of being cut-off from the main plateau ice supply