815 research outputs found

    The SOFIA Massive (SOMA) Star Formation Survey. II. High Luminosity Protostars

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    We present multi-wavelength images observed with SOFIA-FORCAST from ∼\sim10 to 40 μ\mum of seven high luminosity massive protostars, as part of the SOFIA Massive (SOMA) Star Formation Survey. Source morphologies at these wavelengths appear to be influenced by outflow cavities and extinction from dense gas surrounding the protostars. Using these images, we build spectral energy distributions (SEDs) of the protostars, also including archival data from Spitzer, Herschel and other facilities. Radiative transfer (RT) models of Zhang & Tan (2018), based on Turbulent Core Accretion theory, are then fit to the SEDs to estimate key properties of the protostars. Considering the best five models fit to each source, the protostars have masses m∗∼12−64 M⊙m_{*} \sim 12-64 \: M_{\odot} accreting at rates of m˙∗∼10−4−10−3 M⊙ yr−1\dot{m}_{*} \sim 10^{-4}-10^{-3} \: M_{\odot} \: \rm yr^{-1} inside cores of initial masses Mc∼100−500 M⊙M_{c} \sim 100-500 \: M_{\odot} embedded in clumps with mass surface densities Σcl∼0.1−3 g cm−2\Sigma_{\rm cl} \sim 0.1-3 \: \rm g \: cm^{-2} and span a luminosity range of 104−106 L⊙10^{4} -10^{6} \: L_{\odot}. Compared with the first eight protostars in Paper I, the sources analyzed here are more luminous, and thus likely to be more massive protostars. They are often in a clustered environment or have a companion protostar relatively nearby. From the range of parameter space of the models, we do not see any evidence that Σcl\Sigma_{\rm cl} needs to be high to form these massive stars. For most sources the RT models provide reasonable fits to the SEDs, though the cold clump material often influences the long wavelength fitting. However, for sources in very clustered environments, the model SEDs may not be such a good description of the data, indicating potential limitations of the models for these regions.Comment: 30 pages, 19 figures, Accepted for publication in Ap

    The SOFIA Massive (SOMA) Star Formation Survey. I. Overview and First Results

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    We present an overview and first results of the Stratospheric Observatory For Infrared Astronomy Massive (SOMA) Star Formation Survey, which is using the FORCAST instrument to image massive protostars from ∼10\sim10--40 μm40\:\rm{\mu}\rm{m}. These wavelengths trace thermal emission from warm dust, which in Core Accretion models mainly emerges from the inner regions of protostellar outflow cavities. Dust in dense core envelopes also imprints characteristic extinction patterns at these wavelengths, causing intensity peaks to shift along the outflow axis and profiles to become more symmetric at longer wavelengths. We present observational results for the first eight protostars in the survey, i.e., multiwavelength images, including some ancillary ground-based MIR observations and archival {\it{Spitzer}} and {\it{Herschel}} data. These images generally show extended MIR/FIR emission along directions consistent with those of known outflows and with shorter wavelength peak flux positions displaced from the protostar along the blueshifted, near-facing sides, thus confirming qualitative predictions of Core Accretion models. We then compile spectral energy distributions and use these to derive protostellar properties by fitting theoretical radiative transfer models. Zhang and Tan models, based on the Turbulent Core Model of McKee and Tan, imply the sources have protostellar masses m∗∼10m_*\sim10--50 M⊙\:M_\odot accreting at ∼10−4\sim10^{-4}--10−3 M⊙ yr−110^{-3}\:M_\odot\:{\rm{yr}}^{-1} inside cores of initial masses Mc∼30M_c\sim30--500 M⊙\:M_\odot embedded in clumps with mass surface densities Σcl∼0.1\Sigma_{\rm{cl}}\sim0.1--3 g cm−2\:{\rm{g\:cm}^{-2}}. Fitting Robitaille et al. models typically leads to slightly higher protostellar masses, but with disk accretion rates ∼100×\sim100\times smaller. We discuss reasons for these differences and overall implications of these first survey results for massive star formation theories.Comment: Accepted to ApJ, 32 page

    A Massive Protostar Forming by Ordered Collapse of a Dense, Massive Core

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    We present 30 and 40 micron imaging of the massive protostar G35.20-0.74 with SOFIA-FORCAST. The high surface density of the natal core around the protostar leads to high extinction, even at these relatively long wavelengths, causing the observed flux to be dominated by that emerging from the near-facing outflow cavity. However, emission from the far-facing cavity is still clearly detected. We combine these results with fluxes from the near-infrared to mm to construct a spectral energy distribution (SED). For isotropic emission the bolometric luminosity would be 3.3x10^4 Lsun. We perform radiative transfer modeling of a protostar forming by ordered, symmetric collapse from a massive core bounded by a clump with high mass surface density, Sigma_cl. To fit the SED requires protostellar masses ~20-34 Msun depending on the outflow cavity opening angle (35 - 50 degrees), and Sigma_cl ~ 0.4-1 g cm-2. After accounting for the foreground extinction and the flashlight effect, the true bolometric luminosity is ~ (0.7-2.2)x10^5 Lsun. One of these models also has excellent agreement with the observed intensity profiles along the outflow axis at 10, 18, 31 and 37 microns. Overall our results support a model of massive star formation involving the relatively ordered, symmetric collapse of a massive, dense core and the launching bipolar outflows that clear low density cavities. Thus a unified model may apply for the formation of both low and high mass stars.Comment: 6 pages, 4 figures, 1 table, accepted to Ap

    Nurses\u27 Alumnae Association Bulletin - Volume 6 Number 10

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    Financial Report Calendar of Events Attention, Class of 1945! Miss Shafer Retires Review of the Alumnae Association Meetings Institutional Staff Nurses\u27 Section Report of Staff Activites - 1948-1949 The Staff Stockings! Stockings! Stockings! Pop-Up Toaster It\u27s Not Too Soon Any White Elephants? Private Duty Section The Jefferson Hospital Private Duty Nurses\u27 Register Report for Barton Memorial Hospital Progress of the Orthopedic Department Just Under the Date Line Pediatrics at Jefferson Controlled Respiration in Anesthesia Anesthesia Progress Physical Advances at Jefferson During the Past Year The White Haven Division The Clara Melville Scholarship Fund The Relief Fund The Busy Year for the Nurses\u27 Home Committee of the Women\u27s Board The Gray Ladies Memories Lost Miscellaneous Items Medical College News Marriages Births Deaths Condolences Prizes District No. 1 Dues Help! Help! Help! Jap Prison School Spurs Nurse to Win University Degree Twenty Ways to Kill an Organization The Bulletin Committee Attention, Alumnae New Addresse

    Nurses\u27 Alumnae Association Bulletin - Volume 7 Number 11

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    Anna M. Shafer Barton Memorial Division Births Changes in the Ophthalmology Division Change of Address Clara Melville Fund Continental Tour Deceased Digest of Meetings Inter-County Hospitalization Plan Katherine Childs\u27 Letter Lost Members Marriages Miscellaneous Nursing Home Committee\u27s Report Physical Advantages President James L. Kauffman\u27s Letter President\u27s Greeting Private Duty Section Prizes Relief Fund School Nursing Silhouette of a Public Health Nurse Rooming-in of Infant with Mother Staff Activities The Student White Haven Divisio

    Locally advanced adenocarcinoma and adenosquamous carcinomas of the cervix compared to squamous cell carcinomas of the cervix in gynecologic oncology group trials of cisplatin-based chemoradiation

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    OBJECTIVE: Conflicting results have been reported for adeno- and adenosquamous carcinomas of the cervix with respect to their response to therapy and prognosis. The current study sought to evaluate impact of adeno- and adenosquamous histology in the randomized trials of primary cisplatin-based chemoradiation for locally advanced cervical cancer. METHODS: Patients with adeno- and adenosquamous cervical carcinomas were retrospectively studied and compared to squamous cell carcinomas in GOG trials of chemoradiation. RESULTS: Among 1671 enrolled in clinical trials of chemoradiation, 182 adeno- and adenosquamous carcinomas were identified (10.9%). A higher percentage of adeno- and adenosquamous carcinomas were stage IB2 (27.5% versus 20.0%) and fewer had stage IIIB (21.4% versus 28.6%). The mean tumor size was larger for squamous than adeno- and adenosquamous. Adeno- and adenosquamous carcinomas were more often poorly differentiated (46.2% versus 26.8%). When treated with radiation therapy alone, the 70 patients with adeno- and adenosquamous carcinoma of the cervix showed a statistically poorer overall survival (p=0.0499) compared to the 647 patients with squamous cell carcinoma of the cervix. However, when treated with radiation therapy with concurrent cisplatin-based chemotherapy, the 112 patients with adeno- and adenosquamous carcinomas had a similar overall survival (p=0.459) compared the 842 patients with squamous cell carcinoma. Adverse effects to treatment were similar across histologies. CONCLUSION: Adeno- and adenosquamous carcinomas of the cervix are associated with worse overall survival when treated with radiation alone but with similar progression-free and overall survival compared to squamous cell carcinomas of the cervix when treated with cisplatin based chemoradiation

    Contextualizing our Leadership Education Approach to Complex Problem Solving: Shifting Paradigms and Evolving Knowledge: Priority 5 of the National Leadership Education Research Agenda 2020–2025

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    Complex problems characterized by uncertainty, interconnectedness, poorly defined goals, and high risk are not new to the human experience. Yet humanity is increasingly faced with multifaceted and pervasive global challenges, and leadership education must adapt accordingly. These complex problems transcend borders and require a collective, adaptive, and iterative learning response. Complex problems such as failure to act on climate change, unemployment, food crises, governance failures, pandemics, cyberattacks, and involuntary migration are interrelated challenges that require paradigm shifts in responses and leadership (Global Risk Report, 2020)
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