TIMASSS : The IRAS16293-2422 Millimeter And Submillimeter Spectral Survey: Tentative Detection of Deuterated Methyl Formate (DCOOCH3)

High deuterium fractionation is observed in various types of environment such as prestellar cores, hot cores and hot corinos. It has proven to be an efficient probe to study the physical and chemical conditions of these environments. The study of the deuteration of different molecules helps us to understand their formation. This is especially interesting for complex molecules such as methanol and bigger molecules for which it may allow to differentiate between gas-phase and solid-state formation pathways. Methanol exhibits a high deuterium fractionation in hot corinos. Since CH3OH is thought to be a precursor of methyl formate we expect that deuterated methyl formate is produced in such environments. We have searched for the singly-deuterated isotopologue of methyl formate, DCOOCH3, in IRAS 16293-2422, a hot corino well-known for its high degree of methanol deuteration. We have used the IRAM/JCMT unbiased spectral survey of IRAS 16293-2422 which allows us to search for the DCOOCH3 rotational transitions within the survey spectral range (80-280 GHz, 328-366 GHz). The expected emission of deuterated methyl formate is modelled at LTE and compared with the observations.} We have tentatively detected DCOOCH3 in the protostar IRAS 16293-2422. We assign eight lines detected in the IRAM survey to DCOOCH3. Three of these lines are affected by blending problems and one line is affected by calibration uncertainties, nevertheless the LTE emission model is compatible with the observations. A simple LTE modelling of the two cores in IRAS 16293-2422, based on a previous interferometric study of HCOOCH3, allows us to estimate the amount of DCOOCH3 in IRAS 16293-2422. Adopting an excitation temperature of 100 K and a source size of 2\arcsec and 1\farcs5 for the A and B cores, respectively, we find that N(A,DCOOCH3) = N(B,DCOOCH3) ~ 6.10^14 /cm2. The derived deuterium fractionation is ~ 15%, consistent with values for other deuterated species in this source and much greater than that expected from the deuterium cosmic abundance. DCOOCH3, if its tentative detection is confirmed, should now be considered in theoretical models that study complex molecule formation and their deuteration mechanisms. Experimental work is also needed to investigate the different chemical routes leading to the formation of deuterated methyl formate

Clues to Nuclear Star Cluster Formation from Edge-on Spirals

We find 9 nuclear cluster candidates in a sample of 14 edge-on, late-type galaxies observed with HST/ACS. These clusters have magnitudes (M_I ~ -11) and sizes (r_eff ~ 3pc) similar to those found in previous studies of face-on, late-type spirals and dE galaxies. However, three of the nuclear clusters are significantly flattened and show evidence for multiple, coincident structural components. The elongations of these three clusters are aligned to within 10 degrees of the galaxies' major axes. Structurally, the flattened clusters are well fit by a combination of a spheroid and a disk or ring. The nuclear cluster disks/rings have F606W-F814W (~V-I) colors 0.3-0.6 magnitudes bluer than the spheroid components, suggesting that the stars in these components have ages < 1 Gyr. In NGC 4244, the nearest of the nuclear clusters, we further constrain the stellar populations and provide a lower limit on the dynamical mass via spectroscopy. We also present tentative evidence that another of the nuclear clusters (in NGC 4206) may also host a supermassive black hole. Based on our observational results we propose an in situ formation mechanism for nuclear clusters in which stars form episodically in compact nuclear disks, and then lose angular momentum or heat vertically to form an older spheroidal structure. We estimate the period between star formation episodes to be 0.5 Gyr and discuss possible mechanisms for tranforming the disk-like components into spheroids. We also note the connection between our objects and massive globular clusters (e.g. $\omega$ Cen), UCDs, and SMBHs. (Abridged)Comment: Accepted for publication in the A

A Broad Search for Counterrotating Gas and Stars: Evidence for Mergers and Accretion

We measure the frequency of bulk gas-stellar counterrotation in a sample of 67 galaxies drawn from the Nearby Field Galaxy Survey, a broadly representative survey of the local galaxy population down to M_B-15. We detect 4 counterrotators among 17 E/S0's with extended gas emission (24% +8 -6). In contrast, we find no clear examples of bulk counterrotation among 38 Sa-Sbc spirals, although one Sa does show peculiar gas kinematics. This result implies that, at 95% confidence, no more than 8% of Sa-Sbc spirals are bulk counterrotators. Among types Sc and later, we identify only one possible counterrotator, a Magellanic irregular. We use these results together with the physical properties of the counterrotators to constrain possible origins for this phenomenon.Comment: 19 pages, 4 figures, AJ, accepte

Near-arcsecond resolution observations of the hot corino of the solar type protostar IRAS 16293-2422

Complex organic molecules have previously been discovered in solar type protostars, raising the questions of where and how they form in the envelope. Possible formation mechanisms include grain mantle evaporation, interaction of the outflow with its surroundings or the impact of UV/X-rays inside the cavities. In this Letter we present the first interferometric observations of two complex molecules, CH3CN and HCOOCH3, towards the solar type protostar IRAS16293-2422. The images show that the emission originates from two compact regions centered on the two components of the binary system. We discuss how these results favor the grain mantle evaporation scenario and we investigate the implications of these observations for the chemical composition and physical and dynamical state of the two components.Comment: 5 pages (apjemulate), 2 figures; accepted by ApJ

State of the art in bile analysis in forensic toxicology

AbstractIn forensic toxicology, alternative matrices to blood are useful in case of limited, unavailable or unusable blood sample, suspected postmortem redistribution or long drug intake-to-sampling interval. The present article provides an update on the state of knowledge for the use of bile in forensic toxicology, through a review of the Medline literature from 1970 to May 2015. Bile physiology and technical aspects of analysis (sampling, storage, sample preparation and analytical methods) are reported, to highlight specificities and consequences from an analytical and interpretative point of view. A table summarizes cause of death and quantification in bile and blood of 133 compounds from more than 200 case reports, providing a useful tool for forensic physicians and toxicologists involved in interpreting bile analysis. Qualitative and quantitative interpretation is discussed. As bile/blood concentration ratios are high for numerous molecules or metabolites, bile is a matrix of choice for screening when blood concentrations are low or non-detectable: e.g., cases of weak exposure or long intake-to-death interval. Quantitative applications have been little investigated, but small molecules with low bile/blood concentration ratios seem to be good candidates for quantitative bile-based interpretation. Further experimental data on the mechanism and properties of biliary extraction of xenobiotics of forensic interest are required to improve quantitative interpretation

Extragalactic database. VII Reduction of astrophysical parameters

The Lyon-Meudon Extragalactic database (LEDA) gives a free access to the main astrophysical parameters for more than 100,000 galaxies. The most common names are compiled allowing users to recover quickly any galaxy. All these measured astrophysical parameters are first reduced to a common system according to well defined reduction formulae leading to mean homogeneized parameters. Further, these parameters are also transformed into corrected parameters from widely accepted models. For instance, raw 21-cm line widths are transformed into mean standard widths after correction for instrumental effect and then into maximum velocity rotation properly corrected for inclination and non-circular velocity. This paper presents the reduction formulae for each parameter: coordinates, morphological type and luminosity class, diameter and axis ratio, apparent magnitude (UBV, IR, HI) and colors, maximum velocity rotation and central velocity dispersion, radial velocity, mean surface brightness, distance modulus and absolute magnitude, and group membership. For each of these parameters intermediate quantities are given: galactic extinction, inclination, K-correction etc.. All these parameters are available from direct connexion to LEDA (telnet lmc.univ-lyon1.fr, login: leda, no passwd OR http://www-obs.univ-lyon1.fr/leda ) and distributed on a standard CD-ROM (PGC-ROM 1996) by the Observatoire de Lyon via the CNRS (mail to [email protected]).Comment: 13 pages, 12 figures. The CDROM of the extragalactic database LEDA is available by mailing to: [email protected]

The Baryon Content of Extremely Low Mass Dwarf Galaxies

We investigate the gas content and baryonic Tully-Fisher relationship for extremely low luminosity dwarf galaxies in the absolute magnitude range -13.5 > Mr > -16. The sample is selected from the Sloan Digital Sky Survey and consists of 101 galaxies for which we have obtained follow-up HI observations using the Arecibo Observatory and Green Bank Telescope. This represents the largest homogeneous sample of dwarfs at low luminosities with well-measured HI and optical properties. The sample spans a range of environments, from dense groups to truly isolated galaxies. The average neutral gas fraction is f_gas=0.6, significantly exceeding that of typical gas-rich galaxies at higher luminosities. Dwarf galaxies are therefore less efficient at turning gas into stars over their lifetimes. The strong environmental dependence of the gas fraction distribution demonstrates that while internal processes can reduce the gas fractions to roughly f_gas=0.4, external processes are required to fully remove gas from a dwarf galaxy. The average rotational velocity of our sample is vrot=50 km/s. Including more massive galaxies from the literature, we fit a baryonic Tully-Fisher slope of M_baryon \propto vrot^(3.70+/- 0.15). This slope compares well with CDM models that assume an equal baryon to dark matter ratio at all masses. While gas stripping or other processes may modify the baryon to dark matter ratio for dwarfs in the densest environments, the majority of dwarf galaxies in our sample have not preferentially lost significant baryonic mass relative to more massive galaxies.Comment: 33 pages, 8 figures. Accepted to ApJ. Data available at http://www.ociw.edu/~mgeha/researc

Mid-infrared sources in the ELAIS Deep X-ray Survey

We present a cross‐correlation of the European Large Area Infrared Space Observatory (ISO) survey (ELAIS) with the ELAIS Deep X‐ray Survey of the N1 and N2 fields. There are seven Chandra point sources with matches in the ELAIS Final Analysis 15‐μm catalogue, out of a total of 28 extragalactic ISO sources present in the Chandra fields. Five of these are consistent with active galactic nuclei (AGN) giving an AGN fraction of ∼19 per cent in the 15‐μm flux range 0.8–6 mJy. We have co‐added the hard X‐ray fluxes of the individually undetected ISO sources and find a low significance detection consistent with star formation in the remaining population. We combine our point source cross‐correlation fraction with the XMM–Newton observations of the Lockman Hole and Chandra observations of the Hubble Deep Field North to constrain source count models of the mid‐infrared galaxy population. The low dust‐enshrouded AGN fraction in ELAIS implied by the number of cross‐identifications between the ELAIS mid‐infrared sample and the Chandra point sources is encouraging for the use of mid‐infrared surveys to constrain the cosmic star formation history, provided there are not further large undetected populations of Compton‐thick AGN

HI studies of the Sculptor group galaxies. VIII. The background galaxies: NGC 24 and NGC 45

In order to complete our HI survey of galaxies in the Sculptor group area, VLA observations of NGC 24 and NGC 45 are presented. These two galaxies of similar magnitude M_B ~ -17.4 lie in the background of the Sculptor group and are low surface brightness galaxies, especially NGC 45. The HI distribution and kinematics are regular for NGC 24 while NGC 45 exhibits a kinematical twist of its major axis. A tilted-ring model shows that the position angle of the major axis changes by ~25 degrees. A best-fit model of their mass distribution gives mass-to-light ratios for the stellar disk of 2.5 and 5.2 for NGC 24 and NGC 45 respectively. These values are higher than the ones expected from stellar population synthesis models. Despite the large dark matter contribution, the galaxy mass is still dominated by the stellar component in their very inner regions. These high mass-to-light ratios are typical of what is seen in low surface brightness galaxies and may indicate that, in those galaxies, disks are far from the maximum disk case. The halo parameters derived from the best-fit models are thus lower limits.Comment: 23 pages, 10 figures, accepted for publication in The Astronomical Journa

Planetary Nebulae as standard candles XI. Application to Spiral Galaxies

We report the results of an [O III] lambda 5007 survey for planetary nebulae (PN) in three spiral galaxies: M101 (NGC 5457), M51 (NGC 5194/5195) and M96 (NGC 3368). By comparing on-band/off-band [O III] lambda 5007 images with images taken in H-alpha and broadband R, we identify 65, 64 and 74 PN candidates in each galaxy, respectively. From these data, an adopted M31 distance of 770 kpc, and the empirical planetary nebula luminosity function (PNLF), we derive distances to M101, M51, and M96 of 7.7 +/- 0.5, 8.4 +/- 0.6, and 9.6 +/- 0.6 Mpc. These observations demonstrate that the PNLF technique can be successfully applied to late-type galaxies, and provide an important overlap between the Population I and Population II distance scales. We also discuss some special problems associated with using the PNLF in spiral galaxies, including the effects of dust and the possible presence of [O III] bright supernova remnants.Comment: 38 pages, TeX, with tables included but not figures. Uses epsf.tex and kpnobasic.tex. To be published in the Astophysical Journal. Full paper is available at http://www.astro.psu.edu/users/johnf/Text/research.htm