Molecular line study of the very young protostar IRAM 04191 in Taurus: Infall, rotation, and outflow

We present a detailed millimeter line study of the circumstellar environment of the low-luminosity Class 0 protostar IRAM 04191+1522 in the Taurus molecular cloud. New line observations demonstrate that the ~14000 AU radius protostellar envelope is undergoing both extended infall and fast, differential rotation. Radiative transfer modeling of multitransition CS and C34S maps indicate an infall velocity v_inf ~ 0.15 km/s at r ~ 1500 AU and v_inf ~ 0.1 km/s up to r ~ 11000 AU, as well as a rotational angular velocity Omega ~ 3.9 x 10^{-13} rad/s, strongly decreasing with radius beyond 3500 AU down to a value Omega ~ 1.5-3 x 10^{-14} rad/s at ~ 11000 AU. Two distinct regions, which differ in both their infall and their rotation properties, therefore seem to stand out: the inner part of the envelope (r ~< 2000-4000 AU) is rapidly collapsing and rotating, while the outer part undergoes only moderate infall/contraction and slower rotation. These contrasted features suggest that angular momentum is conserved in the collapsing inner region but efficiently dissipated due to magnetic braking in the slowly contracting outer region. We propose that the inner envelope is in the process of decoupling from the ambient cloud and corresponds to the effective mass reservoir (~0.5 M_sun) from which the central star is being built. Comparison with the rotational properties of other objects in Taurus suggests that IRAM 04191 is at a pivotal stage between a prestellar regime of constant angular velocity enforced by magnetic braking and a dynamical, protostellar regime of nearly conserved angular momentum. The rotation velocity profile we derive for the inner IRAM 04191 envelope should thus set some constraints on the distribution of angular momentum on the scale of the outer Solar system at the onset of protostar/disk formation.Comment: 23 pages, 16 figures, 1 table, Accepted by Astronomy & Astrophysic

Another look into the factor model black box: factor interpretation and structural (in)stability

This paper considers two families of methods allowing to get interpretable factors without imposing their interpretation a priori: factor rotations and sparse PCA. Monte Carlo simulations show their performance in recovering the correct factor structure. In an empirical application with a large U.S. macroeconomic dataset, they recover the same factor structure, offering a clear economic interpretation. This factor representation seems more natural and informative than competitors, offering new lens to disentangle the driving forces within a factor model. In particular, the structural instability appears to be more limited, and of different nature than what was previously found

The permeability of virtual macroporous structures generated by sphere packing models: comparison with analytical models

Realistic porous structures typical of those made by replication of packed beds of spherical particles have been produced by a novel modelling method. Fluid dynamics simulation of the permeability of these structures agrees well with experimental measurements and similar modelling of structures derived from X-ray tomographic images. By varying the model structures the “bottleneck” flow concept proposed by analytical models in the literature was substantiated, confirming the high dependence of permeability on the size of the windows connecting the pores but also highlighting the need for accurate determination of the connectivity of the pores for these models to be accurate

Observations of cometary parent molecules with the IRAM radio telescope

Several rotational transitions of HCN, H2S, H2CO, and CH3OH were detected in comets P/Brorsen-Metcalf 1989 X, Austin (1989c1) and Levy (1990c) with the Institute for Millimeter Radioastronomy (IRAM) 30-m radio telescope. This allows us to determine the production rates of these molecules and to probe the physical conditions of the coma

Aluminum Alloy Stamping with a First Warm Step and a Second Cold Step

This paper describes a way to simultaneously improve the formability and final strength of 6xxx aluminum alloys by doing a two-step stamping process, namely a warm forming step followed by a cold forming step

AgingMapGAN (AMGAN): High-Resolution Controllable Face Aging with Spatially-Aware Conditional GANs

Existing approaches and datasets for face aging produce results skewed towards the mean, with individual variations and expression wrinkles often invisible or overlooked in favor of global patterns such as the fattening of the face. Moreover, they offer little to no control over the way the faces are aged and can difficultly be scaled to large images, thus preventing their usage in many real-world applications. To address these limitations, we present an approach to change the appearance of a high-resolution image using ethnicity-specific aging information and weak spatial supervision to guide the aging process. We demonstrate the advantage of our proposed method in terms of quality, control, and how it can be used on high-definition images while limiting the computational overhead.Comment: Project page: https://despoisj.github.io/AgingMapGAN

HCOOCH3 as a probe of temperature and structure of Orion-KL

We studied the O-bearing molecule HCOOCH3 to characterize the physical conditions of the different molecular source components in Orion-KL. We identify 28 methyl formate emission peaks throughout the 50" field of observations. The two strongest peaks are in the Compact Ridge (MF1) and in the SouthWest of the Hot Core (MF2). Spectral confusion is still prevailing as half of the expected transitions are blended over the region. Assuming that the transitions are thermalized, we derive the temperature at the five main emission peaks. At the MF1 position we find a temperature of 80K in a 1.8"x0.8" beam size and 120K on a larger scale (3.6" x2.2"), suggesting an external source of heating, whereas the temperature is about 130K at the MF2 position on both scales. Transitions of HCOOCH3 in vt=1 are detected as well and the good agreement of the positions on the rotational diagrams between the vt=0 and the vt=1 transitions suggests a similar temperature. The velocity of the gas is between 7.5 and 8.0km/s depending on the positions and column density peaks vary from 1.6x10^16 to 1.6x10^17cm^-2. A second velocity component is observed around 9-10 km/s in a North-South structure stretching from the Compact Ridge up to the BN object; this component is warmer at the MF1 peak. The two other C2H4O2 isomers are not detected and the derived upper limit for the column density is <3x10^14cm^-2 for glycolaldehyde and <2x10^15cm^-2 for acetic acid. From the 223GHz continuum map, we identify several dust clumps with associated gas masses in the range 0.8 to 5.8Msun. Assuming that the HCOOCH3 is spatially distributed as the dust, we find relative abundances of HCOOCH3 in the range <0.1x10^-8 to 5.2x10^-8. We suggest a relation between the methyl formate distribution and shocks as traced by 2.12 mum H2 emission.Comment: Accepted for publication in A&

Learning Long-Term Style-Preserving Blind Video Temporal Consistency

When trying to independently apply image-trained algorithms to successive frames in videos, noxious flickering tends to appear. State-of-the-art post-processing techniques that aim at fostering temporal consistency, generate other temporal artifacts and visually alter the style of videos. We propose a postprocessing model, agnostic to the transformation applied to videos (e.g. style transfer, image manipulation using GANs, etc.), in the form of a recurrent neural network. Our model is trained using a Ping Pong procedure and its corresponding loss, recently introduced for GAN video generation, as well as a novel style preserving perceptual loss. The former improves long-term temporal consistency learning, while the latter fosters style preservation. We evaluate our model on the DAVIS and videvo.net datasets and show that our approach offers state-of-the-art results concerning flicker removal, and better keeps the overall style of the videos than previous approaches

A New Family of Planets ? "Ocean Planets"

A new family of planets is considered which is between rochy terrestrial planets and gaseous giant ones: "Ocean-Planets". We present the possible formation, composition and internal models of these putative planets, including that of their ocean, as well as their possible Exobiology interest. These planets should be detectable by planet detection missions such as Eddington and Kepler, and possibly COROT (lauch scheduled in 2006). They would be ideal targets for spectroscopic missions such as Darwin/TPF.Comment: 15 pages, 3 figures submitted to Icarus notes (10 july 2003