Searching for Trans Ethyl Methyl Ether in Orion KL

We report on the tentative detection of $trans$ Ethyl Methyl Ether (tEME), $t-CH_3CH_2OCH_3$, through the identification of a large number of rotational lines from each one of the spin states of the molecule towards Orion KL. We also search for $gauche$-$trans$-n-propanol, $Gt-n-CH_3CH_2CH_2OH$, an isomer of tEME in the same source. We have identified lines of both species in the IRAM 30m line survey and in the ALMA Science Verification data. We have obtained ALMA maps to establish the spatial distribution of these species. Whereas tEME mainly arises from the compact ridge component of Orion, Gt-n-propanol appears at the emission peak of ethanol (south hot core). The derived column densities of these species at the location of their emission peaks are $\leq(4.0\pm0.8)\times10^{15} cm^{-2}$ and $\leq(1.0\pm0.2)\times10^{15} cm^{-2}$ for tEME and Gt-n-propanol, respectively. The rotational temperature is $\sim100 K$ for both molecules. We also provide maps of $CH_3OCOH$, $CH_3CH_2OCOH$, $CH_3OCH_3$, $CH_3OH$, and $CH_3CH_2OH$ to compare the distribution of these organic saturated O-bearing species containing methyl and ethyl groups in this region. Abundance ratios of related species and upper limits to the abundances of non-detected ethers are provided. We derive an abundance ratio $N(CH_3OCH_3)/N(tEME)\geq150$ in the compact ridge of Orion.Comment: Accepted in A&A Letter

Red Supergiants in the Disk of M81: Tracing the Spatial Distribution of Star Formation 25 Million Years in the Past

Near-infrared images are used to investigate the brightest red stars in the disk of the nearby spiral galaxy M81. Red supergiants (RSGs) form a well-defined sequence on the color-magnitude diagrams (CMDs) that peaks near M_K = -11.5; RSGs with this peak brightness are seen throughout all fields that were studied, indicating that star formation occured over a large part of the M81 disk only ~ 10 Myr in the past. The number of RSGs per unit integrated K-band light is compared at various locations in the disk. We conclude that star-forming activity in M81 during the past 10 - 25 Myr (1) was distributed over a larger fraction of the disk than it is at the present day, and (2) was not restricted to a given radial interval, but was distributed in a manner that closely followed the stellar mass profile. Star counts indicate that the mean SFR of M81 between 10 and 25 Myr in the past was ~ 0.1 solar masses per year, which is not greatly different from the present day SFR estimated from Halpha and FUV emission.Comment: 21 pages of text and 7 postscript figures; to appear in the PAS

Antifreeze in the hot core of Orion - First detection of ethylene glycol in Orion-KL

Comparison of their chemical compositions shows, to first order, a good agreement between the cometary and interstellar abundances. However, a complex O-bearing organic molecule, ethylene glycol (CH$_{2}$OH)$_{2}$, seems to depart from this correlation because it was not easily detected in the interstellar medium although it proved to be rather abundant with respect to other O-bearing species in comet Hale-Bopp. Ethylene glycol thus appears, together with the related molecules glycolaldehyde CH$_{2}$OHCHO and ethanol CH$_{3}$CH$_{2}$OH, as a key species in the comparison of interstellar and cometary ices as well as in any discussion on the formation of cometary matter. We focus here on the analysis of ethylene glycol in the nearest and best studied hot core-like region, Orion-KL. We use ALMA interferometric data because high spatial resolution observations allow us to reduce the line confusion problem with respect to single-dish observations since different molecules are expected to exhibit different spatial distributions. Furthermore, a large spectral bandwidth is needed because many individual transitions are required to securely detect large organic molecules. Confusion and continuum subtraction are major issues and have been handled with care. We have detected the aGg' conformer of ethylene glycol in Orion-KL. The emission is compact and peaks towards the Hot Core close to the main continuum peak, about 2" to the south-west; this distribution is notably different from other O-bearing species. Assuming optically thin lines and local thermodynamic equilibrium, we derive a rotational temperature of 145 K and a column density of 4.6 10$^{15}$ cm$^{-2}$. The limit on the column density of the gGg' conformer is five times lower.Comment: 19 pages, 10 figures, A&A accepte

Gemini Spectroscopy and HST Imaging of the Stellar Cluster Population in Region B of M82

We present new spectroscopic observations of the stellar cluster population of region B in the prototype starburst galaxy M82 obtained with the Gillett Gemini-North 8.1-metre telescope. By coupling the spectroscopy with UBVI photometry acquired with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST), we derive ages, extinctions and radial velocities for seven young massive clusters (YMCs) in region B. We find the clusters to have ages between 70 and 200 Myr and velocities in the range 230 to 350 km/s, while extinctions Av vary between ~1-2.5 mag. We also find evidence of differential extinction across the faces of some clusters which hinders the photometric determination of ages and extinctions in these cases. The cluster radial velocities indicate that the clusters are located at different depths within the disk, and are on regular disk orbits. Our results overall contradict the findings of previous studies, where region B was thought to be a bound region populated by intermediate-age clusters that formed in an independent, offset starburst episode that commenced 600 Myr-1 Gyr ago. Our findings instead suggest that region B is optically bright because of low extinction patches, and this allows us to view the cluster population of the inner M82 disk, which probably formed as a result of the last encounter with M81. This study forms part of a series of papers aimed at studying the cluster population of M82 using deep optical spectroscopy and multi-band photometry.Comment: 12 pages, 8 figures; accepted for publication in The Astrophysical Journa

[CII] emission and star formation in the spiral arms of M31

The CII 158 microns line is the most important coolant of the interstellar medium in galaxies but substantial variations are seen from object to object. The main source of the emission at a galactic scale is still poorly understood. Previous studies of the CII emission in galaxies have a resolution of several kpc or more so the observed emission is an average of different ISM components. The aim of this work is to study, for the first time, the CII emission at the scale of a spiral arm. We want to investigate the origin of this line and its use as a tracer of star formation. We present CII and OI observations of a segment of a spiral arm of M~31 using the Infrared Space Observatory. The CII emission is compared with tracers of neutral gas (CO, HI) and star formation (H\alpha, Spitzer 24 mu.) The similarity of the CII emission with the Ha and 24 mu images is striking when smoothed to the same resolution, whereas the correlation with the neutral gas is much weaker. The CII cooling rate per H atom increases dramatically from ~2.7e-26 ergs/s/atom in the border of the map to ~ 1.4e-25 ergs/s/atom in the regions of star formation. The CII/FIR(42-122) ratio is almost constant at 2%, a factor 3 higher than typically quoted. However, we do not believe that M~31 is unusual. Rather, the whole-galaxy fluxes used for the comparisons include the central regions where the CII/FIR ratio is known to be lower and the resolved observations neither isolate a spiral arm nor include data as far out in the galactic disk as the observations presented here. A fit to published PDR models yields a plausible average solution of G_0~100 and n~3000 for the PDR emission in the regions of star formation in the arm of M31.Comment: 8 pages, 5 figures. To be published by A&A. Low quality figures. High quality version in http://www.obs.u-bordeaux1.fr/Radio/NRodriguez/out/m31.pd

Evidence for the Large-Scale Dissociation of Molecular Gas in the Inner Spiral Arms of M81

We compare the detailed distributions of HI, H alpha, and 150 nm far-UV continuum emission in the spiral arms of M81 at a resolution of 9" (linear resolution 150 pc at 3.7 Mpc distance). The bright H alpha emission peaks are always associated with peaks in the far-UV emission. The converse is not always true; there are many regions of far-UV emission with little corresponding H alpha. The HI and the far-UV are always closely associated, in the sense that the HI is often brightest around the edges of the far-UV emission. The effects of extinction on the morphology are small, even in the far-UV. Extensive far-UV emission, often with little corresponding H alpha, indicates the presence of many ``B-stars'', which produce mostly non-ionizing UV photons. These far-UV photons dissociate a small fraction of an extensive layer of H_2 into HI. The observed morphology can be understood if ``chimneys'' are common in the spiral arms of M81, where holes are blown out of the galactic disk, exposing the bright HII regions and the corresponding far-UV associated with vigorous star formation. These ``naked'' star-forming regions show little obscuration. H_2 is turned into HI by UV photons impinging on the interior surfaces of these chimneys. The intensity of the far-UV radiation measured by UIT can dissociate the underlying H_2 with a typical density of ~10 H nucleii cm**-3 to produce the observed amount of HI in the spiral arms of M81. Except for thin surface layers locally heated in these photo-dissociation regions close to the far-UV sources, the bulk of the molecular gas in the inner disk of M81 is apparently too cold to produce much 12CO(1-0) emission.Comment: 12 pages, Latex. 8 postscript files. Better quality versions of the figures available from ftp://star.herts.ac.uk/pub/Knapen/m81uv . Accepted, Ap

Ogden Type I to III tibial tubercle fractures in skeletally immature patients: Is routine anterior compartment fasciotomy of the leg indicated?

PURPOSE: Determine the frequency of compartment syndrome of the leg after displaced, operatively treated modified Ogden I to III tibial tubercle fractures (TTFxs), evaluate the preoperative assessment and use of advanced imaging, and need for prophylactic fasciotomies. METHODS: Retrospective analysis of operatively treated, displaced modified Ogden I to III TTFxs, at our level 1 paediatric trauma centre between 2007 and 2019. Modified Ogden Type IV and V fracture patterns were excluded. Fracture patterns were determined by plain radiographs. RESULTS: There were 49 modified Ogden I to III TTFxs in 48 patients. None had signs nor symptoms of vascular compromise, compartment syndromes or impending compartment syndromes preoperatively. In all, 13 of the 49 fractures underwent anterior compartment fasciotomy at surgery; eight of the 13 had traumatic fascial disruptions, which were extended surgically. All incisions were primarily closed. There were no instances of postoperative compartment syndromes, growth arrest, leg-length discrepancy or recurvatum deformity postoperatively. All patients achieved radiographic union and achieved full range of movement. CONCLUSION: The potentially devastating complications of compartment syndrome or vascular compromise following TTFx did not occur in this consecutive series of patients over 12 years. The presence of an intact posterior proximal tibial physis and posterior metaphyseal cortex (Modified Ogden TTFx Type I to III) may mitigate the occurrence of vascular injury and compartment syndrome. Plain radiographs appear appropriate as the primary method of imaging TTFxs, with use of advanced imaging as the clinical scenario dictates. Routine, prophylactic fasciotomies do not appear necessary in Ogden I to III TTFxs, but should be performed for signs and symptoms of compartment syndrome. LEVEL OF EVIDENCE: Level IV

Deep Near-Infrared Imaging of a Field in the Outer Disk of M82 with the ALTAIR Adaptive Optics System on Gemini North

Deep H and K' images, recorded with the ALTAIR adaptive optics system and NIRI imager on Gemini North, are used to probe the red stellar content in a field with a projected distance of 1 kpc above the disk plane of the starburst galaxy M82. The data have an angular resolution of 0.08 arcsec FWHM, and individual AGB and RGB stars are resolved. The AGB extends to at least 1.7 mag in K above the RGB-tip, which occurs at K = 21.7. The relative numbers of bright AGB stars and RGB stars are consistent with stellar evolution models, and one of the brightest AGB stars has an H-K color and K brightness that is consistent with it being a C star. The brightnesses of the AGB stars suggest that they formed during intermediate epochs, possibily after the last major interaction with M81. Therefore, star formation in M82 during intermediate epochs may not have been restricted to the plane of the disk.Comment: 16 pages of text plus 7 postscript figures; to appear in the PAS

The Eastern Arm of M83 Revisited: High-Resolution Mapping of 12CO 1-0 Emission

We have used the Owens Valley Millimeter Array to map 12CO (J=1-0) along a 3.5 kpc segment of M83's eastern spiral arm at resolutions of 6.5"x3.5", 10", and 16". The CO emission in most of this segment lies along the sharp dust lane demarking the inner edge of the spiral arm, but beyond a certain point along the arm the emission shifts downstream from the dust lane to become better aligned with the young stars seen in blue and H-beta images. This morphology resembles that of the western arm of M100. Three possibilities, none of which is wholly satisfactory, are considered to explain the deviation of the CO arm from the dust lane: heating of the CO by UV radiation from young stars, heating by low-energy cosmic rays, and a molecular medium consisting of two (diffuse and dense) components which react differently to the density wave. Regardless, the question of what CO emission traces along this spiral arm is a complicated one. Strong tangential streaming is observed where the arm crosses the kinematic major axis of the galaxy, implying that the shear becomes locally prograde in the arms. Inferred from the streaming is a very high gas surface density of about 230 solar masses/pc**2 and an arm-interarm contrast greater than 2.3 in the part of the arm near the major axis. Using two different criteria, we find that the gas at this location is well above the threshold for gravitational instability -- much more clearly so than in either M51 or M100.Comment: Accepted for publication in ApJ. 25 pages, 5 figures. Manuscript in LaTeX, figures in pdf. Fig 3 in colo

Relations between cognition and motricity in children with neonatal arterial ischemic stroke

Introduction and goalPerinatal arterial ischemic stroke (PAIS) affects one child for 4000 births. The few studies about cognitive development specific to PAIS showed that cognitive performances in this population do not follow up a normal development (Westmacott et al., 2010; Ricci et al., 2008). Based on new data about relation between motricity and cognition (Smits-Engelsman et Hill, 2012), and on the theory of the embodied cognition, led us to hypothesize that cognitive performances would be correlated to the motor performances in children with PAIS.Patients and methodologyWe tested 77 7 years old children meeting the criteria of neonatal AIS, with a diagnosis before the 28th day of life relying on cerebral imagery. After excluding children with seizure and bi-hemispheric lesion, 56 children participated to our study. The cognitive evaluation was performed with the Wechsler Intelligence Scale for Children (WISC-4), the motor evaluation relied on testing of gross motor of the upper arm (Box and Block Test) and fine prehension test (“Nine Hole Peg Test”). The localisation of the lesion, the economic level of parents, the gender, sensory impairments and the presence of hemiplegia were collected. We analyzed these results with simple linear regression.ResultsThe main result of our study is the significative correlation (P<0.03) between scores of the WISC4 (except for working memory index) and motor results. In contrast we did not find any correlation between the scores of the WISC4 and the presence of hemiplegia or with lesion localization.DiscussionMany brain networks develop during the first year through sensorimotor experiences, which contribute to the emergence of knowledge. This concept of development, supported by the approach embodied cognition, can explain the correlations between cognition and motor found in our work and in several studies with children with other early neurological damage