A deeply embedded young protoplanetary disk around L1489 IRS observed by the submillimeter array

Circumstellar disks are expected to form early in the process that leads to the formation of a young star, during the collapse of the dense molecular cloud core. It is currently not well understood at what stage of the collapse the disk is formed or how it subsequently evolves. We aim to identify whether an embedded Keplerian protoplanetary disk resides in the L1489 IRS system. Given the amount of envelope material still present, such a disk would respresent a very young example of a protoplanetary disk. Using the Submillimeter Array (SMA) we have observed the HCO$^+$ $J=$ 3--2 line with a resolution of about 1$''$. At this resolution a protoplanetary disk with a radius of a few hundred AUs should be detectable, if present. Radiative transfer tools are used to model the emission from both continuum and line data. We find that these data are consistent with theoretical models of a collapsing envelope and Keplerian circumstellar disk. Models reproducing both the SED and the interferometric continuum observations reveal that the disk is inclined by 40$^\circ$ which is significantly different to the surrounding envelope (74$^\circ$). This misalignment of the angular momentum axes may be caused by a gradient within the angular momentum in the parental cloud or if L1489 IRS is a binary system rather than just a single star. In the latter case, future observations looking for variability at sub-arcsecond scales may be able to constrain these dynamical variations directly. However, if stars form from turbulent cores, the accreting material will not have a constant angular momentum axis (although the average is well defined and conserved) in which case it is more likely to have a misalignment of the angular momentum axes of the disk and the envelope.Comment: 11 pages, 13 figures, accepted by A&

Classifying the embedded young stellar population in Perseus and Taurus & the LOMASS database

Context. The classification of young stellar objects (YSOs) is typically done using the infrared spectral slope or bolometric temperature, but either can result in contamination of samples. More accurate methods to determine the evolutionary stage of YSOs will improve the reliability of statistics for the embedded YSO population and provide more robust stage lifetimes. Aims. We aim to separate the truly embedded YSOs from more evolved sources. Methods. Maps of HCO+ J=4-3 and C18O J=3-2 were observed with HARP on the James Clerk Maxwell Telescope (JCMT) for a sample of 56 candidate YSOs in Perseus and Taurus in order to characterize emission from high (column) density gas. These are supplemented with archival dust continuum maps observed with SCUBA on the JCMT and Herschel PACS to compare the morphology of the gas and dust in the protostellar envelopes. The spatial concentration of HCO+ J=4-3 and 850 micron dust emission are used to classify the embedded nature of YSOs. Results. Approximately 30% of Class 0+I sources in Perseus and Taurus are not Stage I, but are likely to be more evolved Stage II pre-main sequence (PMS) stars with disks. An additional 16% are confused sources with an uncertain evolutionary stage. Conclusions. Separating classifications by cloud reveals that a high percentage of the Class 0+I sources in the Perseus star forming region are truly embedded Stage I sources (71%), while the Taurus cloud hosts a majority of evolved PMS stars with disks (68%). The concentration factor method is useful to correct misidentified embedded YSOs, yielding higher accuracy for YSO population statistics and Stage timescales. Current estimates (0.54 Myr) may overpredict the Stage I lifetime on the order of 30%, resulting in timescales of 0.38 Myr for the embedded phase.Comment: 33 pages, 21 figures, 6 tables, Accepted to be published in A&

Methanol maps of low-mass protostellar systems: the Serpens Molecular Core

Observations of Serpens have been performed at the JCMT using Harp-B. Maps over a 4.5'x5.4' region were made in a frequency window around 338 GHz, covering the 7-6 transitions of methanol. Emission is extended over each source, following the column density of H2 but showing up also particularly strongly around outflows. The rotational temperature is low, 15-20 K, and does not vary with position within each source. The abundance is typically 10^-9 - 10^-8 with respect to H2 in the outer envelope, whereas "jumps" by factors of up to 10^2 -10^3 inside the region where the dust temperature exceeds 100 K are not excluded. A factor of up to ~ 10^3 enhancement is seen in outflow gas. In one object, SMM4, the ice abundance has been measured to be ~ 3x10^-5 with respect to H2 in the outer envelope, i.e., a factor of 10^3 larger than the gas-phase abundance. Comparison with C18O J=3-2 emission shows that strong CO depletion leads to a high gas-phase abundance of CH3OH not just for the Serpens sources, but for a larger sample of protostars. The observations illustrate the large-scale, low-level desorption of CH3OH from dust grains, extending out to and beyond 7500 AU from each source, a scenario which is consistent with non-thermal (photo-)desorption from the ice. The observations also illustrate the usefulness of CH3OH as a tracer of energetic input in the form of outflows, where methanol is sputtered from the grain surfaces. Finally, the observations provide further evidence of CH3OH formation through CO hydrogenation proceeding on grain surfaces in low-mass envelopes.Comment: Accepted for publication in A&A

The influence of persistent organic pollutants in the traditional Inuit diet on markers of inflammation

Concentrations of persistent organic pollutants (POPs) are high in Inuit living predominately on the traditional marine diet. Adverse effects of POPs include disruption of the immune system and cardiovascular diseases that are frequent in Greenland Inuit. We aimed to assess the association between exposure to POPs from the marine diet and inflammation, taking into account other factors such as vitamin D. We invited Inuit and non-Inuit living in settlements or the town in rural East Greenland or in the capital city Nuuk. Participants completed a food frequency questionnaire and donated a blood sample for measurement of the two markers of inflammation YKL-40 and hsCRP, 25-hydroxy-vitamin D, eleven organochlorine pesticides (OCPs), fourteen polychlorinated biphenyls (PCBs), one polybrominated biphenyl, and nine polybrominated diphenyl ethers (PBDEs) adjusted to the serum lipid content. Participants were 50 through 69 years old, living in settlements, town or city (n = 151/173/211; 95% participation rate). ΣOCP, ΣPCB and ΣPBDE serum levels were higher in Inuit than in non-Inuit (p<0.001/ p<0.001/ p<0.001), in older individuals (p<0.001/p<0.001/p = 0.002) and in participants with the highest intake of Greenlandic food items (p<0.001/p<0.001/p<0.001). Both YKL-40 and hsCRP serum levels were higher in Inuit compared to non-Inuit (p<0.001/p = 0.001), and increased with age (p<0.001/p = 0.001) and with the intake of Greenlandic food items (p<0.001/p = 0.002). Multivariate analysis conformed to a marked influence on both YKL-40 and hsCRP by ΣOCP (p<0.001/p<0.001) and ΣPCBs (p<0.001/p = 0.001) after adjusting for age, BMI, vitamin D, alcohol and smoking. POP levels were associated with the intake of the traditional Inuit diet and with markers of inflammation. This supports a pro-inflammatory role of POPs to promote chronic diseases common to populations in Greenland. These data inform guidelines on 'the Arctic dilemma' and encourage follow-up on the ageing Arctic populations

Open ventral hernia repair with a composite ventral patch : final results of a multicenter prospective study

Background: This study assessed clinical outcomes, including safety and recurrence, from the two-year follow-up of patients who underwent open ventral primary hernia repair with the use of the Parietex (TM) Composite Ventral Patch (PCO-VP). Methods: A prospective single-arm, multicenter study of 126 patients undergoing open ventral hernia repair for umbilical and epigastric hernias with the PCO-VP was performed. Results: One hundred twenty-six subjects (110 with umbilical hernia and 16 with epigastric hernia) with a mean hernia diameter of 1.8cm (0.4-4.0) were treated with PCO-VP. One hundred subjects completed the two-year study. Cumulative hernia recurrence was 3.0% (3/101; 95%CI: 0.0-6.3%) within 24months. Median Numeric Rating Scale pain scores improved from 2 [0-10] at baseline to 0 [0-3] at 1 month (P<0.001) and remained low at 24months 0 [0-6] (P<0.001). 99% (102/103) of the patients were satisfied with their repair at 24months postoperative. Conclusions: The use of PCO-VP to repair primary umbilical and epigastric defects yielded a low recurrence rate, low postoperative and chronic pain, and high satisfaction ratings, confirming that PCO-VP is effective for small ventral hernia repair in the two-year term after implantation. Trial registration: The study was registered publically at clinicaltrials.gov (NCT01848184 registered May 7, 2013)

Manipulating the torsion of molecules by strong laser pulses

A proof-of-principle experiment is reported, where torsional motion of a molecule, consisting of a pair of phenyl rings, is induced by strong laser pulses. A nanosecond laser pulse spatially aligns the carbon-carbon bond axis, connecting the two phenyl rings, allowing a perpendicularly polarized, intense femtosecond pulse to initiate torsional motion accompanied by an overall rotation about the fixed axis. The induced motion is monitored by femtosecond time-resolved Coulomb explosion imaging. Our theoretical analysis accounts for and generalizes the experimental findings.Comment: 4 pages, 4 figures, submitted to PRL; Major revision of the presentation of the material; Correction of ion labels in Fig. 2(a

Current Star Formation in the Ophiuchus and Perseus Molecular Clouds: Constraints and Comparisons from Unbiased Submillimeter and Mid-Infrared Surveys. II

We present a census of the population of deeply embedded young stellar objects (YSOs) in the Ophiuchus molecular cloud complex based on a combination of Spitzer Space Telescope mid-infrared data from the "Cores to Disks" (c2d) legacy team and JCMT/SCUBA submillimeter maps from the COMPLETE team. We have applied a method developed for identifying embedded protostars in Perseus to these datasets and in this way construct a relatively unbiased sample of 27 candidate embedded protostars with envelopes more massive than our sensitivity limit (about 0.1 M_sun). Embedded YSOs are found in 35% of the SCUBA cores - less than in Perseus (58%). On the other hand the mid-infrared sources in Ophiuchus have less red mid-infrared colors, possibly indicating that they are less embedded. We apply a nearest neighbor surface density algorithm to define the substructure in each of the clouds and calculate characteristic numbers for each subregion - including masses, star formation efficiencies, fraction of embedded sources etc. Generally the main clusters in Ophiuchus and Perseus (L1688, NGC1333 and IC348) are found to have higher star formation efficiencies than small groups such as B1, L1455 and L1448, which on the other hand are completely dominated by deeply embedded protostars. We discuss possible explanations for the differences between the regions in Perseus and Ophiuchus, such as different evolutionary timescales for the YSOs or differences, e.g., in the accretion in the two clouds.Comment: Accepted for publication in ApJ (56 pages, 13 figures; abstract abridged). Version with full-resolution figures available at http://www.astro.uni-bonn.de/~jes/paper120.pd

Chemistry of a newly detected circumbinary disk in Ophiuchus

(Abridged) Astronomers recently started discovering exoplanets around binary systems. Therefore, understanding the formation and evolution of circumbinary disks is crucial for a complete scenario of planet formation. The aim of this paper is to present the detection of a circumbinary disk around Oph-IRS67 and analyse its structure. We present high-angular-resolution (0.4", 60 AU) observations of C17O, H13CO+ , C34S, SO2, C2H and c-C3H2 molecular transitions with ALMA at 0.8 mm. The spectrally and spatially resolved maps reveal the kinematics of the circumbinary disk as well as its chemistry. Molecular abundances are estimated using RADEX. The continuum emission reveals the presence of a circumbinary disk around the two sources. This disk has a diameter of ~620 AU and is well traced by C17O and H13CO+ emission. C2H and c-C3H2 trace a higher-density region which is spatially offset from the sources (~430 AU). Finally, SO2 shows compact emission around one of the sources, Oph-IRS67 B. The molecular transitions which trace the circumbinary disk are consistent with a Keplerian profile on disk scales (< 200 AU) and an infalling profile for envelope scales (> 200 AU). The Keplerian fit leads to a mass of 2.2 Msun. Inferred CO abundances w.r.t. H2 are comparable to the canonical ISM value of 2.7e-4. This study proves the first detection of the circumbinary disk associated with Oph-IRS67. The disk is chemically differentiated from the nearby high-density region. The lack of methanol emission suggests the extended disk dominates the mass budget in the inner- most regions of the protostellar envelope, generating a flat density profile where less material is exposed to high temperatures. Thus, complex organic molecules would be associated with lower column densities. Finally, Oph-IRS67 is a promising candidate for the detection of both circumstellar disks with higher-angular-resolution observations.Comment: 19 pages, 14 figures, 6 table