Gas-phase processes were long thought to be the key formation mechanisms for complex organic molecules in star-forming regions. However, recent experimental and theoretical evidence has cast doubt on efficiency of such processes. Grain-surface chemistry is frequently invoked as a solution, but until now there have been no quantitative models taking into account both high degree chemical complexity evolving physical conditions Here, we introduce new gas-grain network, wherein wide array...

(Abridged) Protoplanetary disks are vital objects in star and planet formation, possessing all the material which may form a planetary system orbiting new star. We investigate synthesis of complex organic molecules (COMs) to constrain achievable chemical complexity predict species transitions be observable with ALMA. have coupled 2D model protoplanetary disk around T Tauri gas-grain network including COMs. compare synthesised line intensities calculated column densities observations...

Memory problems are a major source of concern among older adults. The goal this research was to evaluate methods for improving memory performance and beliefs about ability control. Men women between the ages 60 85 were randomly assigned one five treatment groups: (1) cognitive restructuring promote adaptive memory, (2) skills training, (3) combined (4) practice on tasks, (5) no-contact control group. Beliefs (ability control) (working recall text materials, categorizable word list, names...

ABSTRACT The first detection of gas-phase methanol in a protoplanetary disk (TW Hya) is presented. In addition to being one the largest molecules detected disks date, also organic molecule with an unambiguous ice chemistry origin. stacked emission, as observed Atacama Large Millimeter/submillimeter Array, spectrally resolved and across six velocity channels ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>&gt;</mml:mo> <mml:mn>3</mml:mn>...

Both grain surface and gas phase chemistry have been invoked to explain the disparate relative abundances of methyl formate its structural isomers acetic acid glycolaldehyde in Sgr B2(N) star-forming region. While a network involving radical–radical reactions during warm-up hot core is most chemically viable option proposed date, neither qualitative nor quantitative agreement between modeling observation has yet obtained. In this study, we seek test additional processes further investigate...

Using CARMA, we imaged the 87 GHz SiO v = 0 J 2–1 line toward Orion-KL with 045 angular resolution. The maps indicate that radio source I drives a bipolar outflow into surrounding molecular cloud along NE–SW axis, in agreement model of Greenhill et al. extended high-velocity from appears to be continuation this compact outflow. High-velocity gas extends farthest NW–SE suggesting direction changes on timescales few hundred years.

We present the analysis of NOEMA interferometric observations high-mass star-forming region W75N(B) with a focus on molecular composition and distribution prebiotic molecules in source's multiple cores. Over twenty are identified across region, many being fit for column density, rotational temperature, spectral line full width half maximum, v$_{lsr}$. This work includes first known detection initial complex organic MM2 MM3 regions. Furthermore, parameter maps were created from six that well...

The presence of over 300 molecules in the interstellar medium, majority which are organic compounds, raises question extent to protostellar chemistry is responsible for Solar System bodies (e.g., comets, asteroids, planets). systematic surveys cold cores have focused on TMC-1 core Taurus complex, along with lesser other northern hemisphere facilitated by several telescopes available below 45 GHz, where most relatively strong emission under conditions cores. A few southern sources been...

Abstract We present the analysis of NOEMA interferometric observations high-mass star-forming region W75N(B) with a focus on molecular composition and distribution prebiotic molecules in source’s multiple cores. Over 20 are identified across region, many being fit for column density, rotational temperature, spectral line FWHM, v lsr . This work includes first known detection initial complex organic MM2 MM3 regions. Furthermore, parameter maps were created from six that well The emission was...

Methyl formate presents a challenge for the conventional chemical mechanisms assumed to guide interstellar organic chemistry. Previous studies of potential formation pathways methyl in clouds ruled out gas-phase chemistry as major production route, and more recent kinetics models indicate that it may form efficiently from radical-radical on ice surfaces. Yet, imaging molecules potentially related its suggest through previously unexplored Motivated by these findings, two new ion-molecule...

A computational study of O(1D) insertion reactions with methanol (CH3OH), dimethyl ether (CH3OCH3), and methyl amine (CH3NH2) was performed to guide laboratory investigations the product molecules methanediol (HOCH2OH), methoxymethanol (CH3OCH2OH), aminomethanol (HOCH2NH2), respectively. The minimum energy higher conformer geometries products were determined at MP2/aug-cc-pVTZ level theory, CCSD(T)/aug-cc-pVTZ calculations on reactants, products, transitions states examine reaction...

Abstract Spectral line surveys are an indispensable tool for exploring the physical and chemical evolution of astrophysical environments due to vast amount data that can be obtained in a relatively short time. We present deep, broadband spectral 30 interstellar clouds using two λ = 1.3 mm receivers at Caltech Submillimeter Observatory. This information used probe influence environment on molecular complexity. observed wide variety sources examine relative abundances organic molecules as they...

Glycolaldehyde (HOCH2CHO) is a sugar-related interstellar prebiotic molecule that has been detected in two star-forming regions, Sgr B2(N) and G31.41+0.31. suspected to form from photodissociation-driven ice chemistry, therefore can be used trace complex organic chemistry environments. The relative abundance of glycolaldehyde its structural isomers, methyl formate (HCOOCH3) acetic acid (CH3COOH), constrain astrochemical models. Given central role the medium, suggested as prime molecular...

Although molecular oxygen, O2, has long been thought to be present in interstellar environments, it only tentatively detected toward one cloud. The fractional abundance of O2 determined from these observations is well below that predicted by astrochemical models. Given the difficulty ground-based telescopes, identification a molecule could used as tracer environments would quite useful. To this end, we have undertaken collaborative examination HO+2 an attempt evaluate feasibility its...

It has recently been suggested that chemical processing can shape the spatial distributions of complex molecules in Orion-KL region and leads to nitrogen–oxygen "chemical differentiation" seen previous observations this source. is a very dynamic region, it therefore also possible physical conditions molecular Only high resolution provide information needed disentangle these effects. Here, we present millimeter imaging studies at various beam sizes using Combined Array for Research...

The birth environment of the Sun will have influenced physical and chemical structure pre-solar nebula, including attainable complexity reached in disk, important for prebiotic chemistry. formation distribution complex organic molecules (COMs) a disk around T Tauri star is investigated two scenarios: (i) an isolated (ii) irradiated externally by nearby massive star. chemistry calculated along accretion flow from outer inwards using comprehensive network which includes gas-phase reactions,...

A new laboratory technique has been developed that utilizes gas-phase, direct-absorption millimeter and submillimeter spectroscopy to detect identify desorbed species from interstellar cometary ice analogues. Rotational is a powerful structure-specific for detecting isomers other possessing the same mass are indistinguishable with spectrometry. Furthermore, resultant spectra directly comparable observational data far-infrared telescopes. Here, we present proof-of-concept measurements of...

The recent advancements in far-infrared (far-IR) astronomy brought about by the Herschel, SOFIA, and ALMA observatories have led to technological millimeterwave submillimeterwave laboratory spectroscopy that is used support molecular observations. This review gives an overview of rotational its relationship with observational astronomy, as well spectroscopic techniques focusing on both historical approaches new advancements. Additional topics discussed include production detection for...

Glycolaldehyde (CHOCH2OH), the simplest two-carbon α-hydroxy aldehyde, has become of great interest in field astrochemistry due to its recent detection toward Sagittarius B2 (N-LMH) molecular cloud. The original interstellar identification was based on an extrapolation prior microwave rotational spectroscopy glycolaldehyde. millimeter and submillimeter spectra this molecule from 128 354 GHz were subsequently measured after detection. We present here spectrum 72 122.5 along with a combined...

A new instrument has been constructed that couples a supersonic expansion source to continuous wave cavity ringdown spectrometer using Fabry–Perot quantum cascade laser (QCL). The purpose of the is enable acquisition cold, rotationally resolved gas phase spectrum buckminsterfullerene (C60). As first test system, high resolution spectra ν8 vibrational band CH2Br2 have acquired at ∼1197 cm−1. To our knowledge, this time not previously recorded with rotational QCL-based spectrometer. 62...

We present here the results of an initial search for 1,3-dihydroxyacetone [or DHA, CO(CH2OH)2], simplest ketose monosaccharide, toward Sagittarius B2(N-LMH) hot core. Nine possible DHA emission lines have been observed with Caltech Submillimeter Observatory, from which a rotational excitation temperature 220 ± 65 K and beam-averaged column density (4.9 2.2) × 1015 cm-2 are derived. If confirmed by additional observations, would be among most abundant complex molecules yet detected. is not...

Recent interferometric observations have called into question the traditional view of Orion-KL region, which displays one most well-defined cases chemical differentiation in a star-forming region. Previous, lower-resolution images show emission signatures for oxygen-bearing organic molecules toward Orion Compact Ridge, and nitrogen-bearing Hot Core. However, more recent at higher spatial resolution indicate that bulk molecular is arising from many smaller, compact clumps are spatially...