A Combined Spitzer and Herschel Infrared Study of Gas and Dust in the Circumbinary Disk Orbiting V4046 Sgr

We present results from a spectroscopic Spitzer and Herschel mid-to-far-infrared study of the circumbinary disk orbiting the evolved (age ~12-23 Myr) close binary T Tauri system V4046 Sgr. Spitzer IRS spectra show emission lines of [Ne II], H_2 S(1), CO_2 and HCN, while Herschel PACS and SPIRE spectra reveal emission from [O I], OH, and tentative detections of H_2O and high-J transitions of CO. We measure [Ne III]/[Ne II] < 0.13, which is comparable to other X-ray/EUV luminous T Tauri stars that lack jets. We use the H_2 S(1) line luminosity to estimate the gas mass in the relatively warm surface layers of the inner disk. The presence of [O I] emission suggests that CO, H_2O, and/or OH is being photodissociated, and the lack of [C I] emission suggests any excess C may be locked up in HCN, CN and other organic molecules. Modeling of silicate dust grain emission features in the mid-infrared indicates that the inner disk is composed mainly of large (r~5 um) amorphous pyroxene and olivine grains (~86% by mass) with a relatively large proportion of crystalline silicates. These results are consistent with other lines of evidence indicating that planet building is ongoing in regions of the disk within ~30 AU of the central, close binary.Comment: 33 pages, 9 figures, 3 tables. Accepted for publication in Ap

Detecting weak spectral lines in interferometric data through matched filtering

Funding: R.A.L. and J.H. gratefully acknowledge funding from National Science Foundation Graduate Research Fellowships (Grant No. DGE-1144152). R.A.L. also acknowledges funding from the NRAO Student Observing Support Program. K.I.Ö. acknowledges funding from the Alfred P. Sloan Foundation and the David and Lucile Packard Foundation. C.W. acknowledges financial support from the Netherlands Organisation for Scientific Research (NWO, grant 639.041.335) and start-up funds from the University of Leeds, UK.Modern radio interferometers enable observations of spectral lines with unprecedented spatial resolution and sensitivity. In spite of these technical advances, many lines of interest are still at best weakly detected and therefore necessitate detection and analysis techniques specialized for the low signal-to-noise ratio (S/N) regime. Matched filters can leverage knowledge of the source structure and kinematics to increase sensitivity of spectral line observations. Application of the filter in the native Fourier domain improves S/N while simultaneously avoiding the computational cost and ambiguities associated with imaging, making matched filtering a fast and robust method for weak spectral line detection. We demonstrate how an approximate matched filter can be constructed from a previously observed line or from a model of the source, and we show how this filter can be used to robustly infer a detection significance for weak spectral lines. When applied to ALMA Cycle 2 observations of CH3OH in the protoplanetary disk around TW Hya, the technique yields a ≈53% S/N boost over aperture-based spectral extraction methods, and we show that an even higher boost will be achieved for observations at higher spatial resolution. A Python-based open-source implementation of this technique is available under the MIT license at http://github.com/AstroChem/VISIBLE.Publisher PDFPeer reviewe

Characteristics of Academic Anesthesiologist’s Elected to an Institutional Academy of Master Educators

Background. The educational experience and success of academic anesthesiologists may be elusive to quantify. We wished to examine the characteristics of a cohort of anesthesiology faculty who were inducted into a medical school master educator academy over the last decade. Methods. After IRB approval with waiver of consent, all 10 anesthesiology faculty inductees into the academy supplied relevant data for their accomplishments at the time of induction in multiple educational domains, including teaching and assessment, mentoring and advising, evidence of scholarship and production of enduring materials, and educational leadership. These were deidentified and analyzed. Results. The cohort had evidence of a consistent, visible footprint in the department, medical school, affiliated associations and state and national professional organizations. These included educational leadership positions, numerous teaching recognition and awards, substantial committee service, active mentorship exceeding usual faculty effort and robust portfolios of publications and presentations related to teaching and/or incorporating and supporting mentees as co-authors. Neither time in rank or academic progress was a limitation with several achieving induction in \u3c 5 years. Conclusions. It is possible for full-time anesthesiology clinicians to achieve success in educational recognition within the medical school body. This summary of characteristics of one department’s cohort may be useful to others seeking such recognition and serve. Based on the aggregate findings, we make recommendations for faculty wishing to pursue excellence in education