483 research outputs found

    Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region; I. Dispersing and Rotating Core around an Intermediate-mass Protostar MMS 7

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    We report the results of H13CO+(1-0), CO(1-0), and 3.3 mm dust continuum observations toward one of the strongest mm-wave sources in OMC-3, MMS 7, with the Nobeyama Millimeter Array (NMA) and the Nobeyama 45 m telescope. With the NMA, we detected centrally-condensed 3.3 mm dust-continuum emission which coincides with the MIR source and the free-free jet. Our combined H13CO+ observations have revealed a disk-like envelope. The size and the mass of the disk-like envelope are 0.15 times 0.11 pc and 5.1 - 9.1 M_sun, respectively. The combined map also shows that the outer portion of the disk-like envelope has a fan-shaped structure which delineates the rim of the CO(1-0) outflow observed with the NMA. The position-velocity (P-V) diagrams in the H13CO+ (1-0) emission show that the velocity field in the disk-like envelope is composed of a dispersing gas motion and a possible rigid-like rotation. The mass dispersing rate is estimated to be (3.4 - 6.0) times 10^-5 M_sun/yr, which implies that MMS 7 has an ability to disperse ~10 M_sun during the protostellar evolutional time of a few times 10^5 yr. The specific angular momentum of the possible rotation in the disk-like envelope is nearly two orders of magnitude larger than that in low-mass cores. The turn-over point of the power law of the angular momentum distribution in the disk-like envelope (< 0.007 pc), which is likely to be related to the outer radius of the central mass accretion, is similar to the size of the 3.3 mm dust condensation. The intermediate-mass protostar MMS 7 is in the last stage of the main accretion phase and that the substantial portion of the outer gas has already been dispersed, while the mass accretion may still be on-going at the innermost region traced by the dusty condensation.Comment: 19 pages, 9 figures, ApJ accepted pape

    Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region. II. Observational Evidence for Outflow-Triggered Star Formation in the OMC-2 FIR 3/4 Region

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    We have carried out the observations of the OMC-2 FIR 3/4 region with the NMA and ASTE in the H13^{13}CO+^{+} (1--0), 12^{12}CO (3--2, 1--0), SiO (vv=0, JJ=2--1), CS (2--1), and CH3_3OH (JKJ_K=7K_K--6K_K) lines and in the 3.3 mm continuum emission. Our NMA observations in the H13^{13}CO+^{+} emission have revealed 0.07 pc-scale dense gas associated with FIR 4. The 12^{12}CO (3--2,1--0) emission shows high-velocity blue and red shifted components at the both north-east and south-west of FIR 3, suggesting a molecular outflow nearly along the plane of the sky driven by FIR 3. The SiO and the CH3_{3}OH emission are detected around the interface between the outflow and the dense gas. Furthermore, the 12^{12}CO (1--0) emission shows an L-shaped structure in the P-V diagram. These results imply presence of the shock due to the interaction between the molecular outflow driven by FIR 3 and the dense gas associated with FIR 4. Moreover, our high angular-resolution observations of FIR 4 in the 3.3 mm continuum emission have first found that FIR 4 consists of eleven dusty cores. The separation among these cores is on the same order of the Jeans length, suggesting that the fragmentation into these cores has been caused by the gravitational instability. The time scale of the fragmentation is similar to the time scale of the interaction between the molecular outflow and the dense gas. We suggest that the interaction between the molecular outflow from FIR 3 and the dense gas associated with FIR 4 triggered the fragmentation into these dusty cores, and hence the next generation the cluster formation.Comment: 13 pages, 9 figures. Accepted by Ap

    Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region. III. An Extensive Survey for Molecular Outflows

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    Using the ASTE 10 m submillimeter telescope and the 1.4 m Infrared Survey Facility (IRSF), we performed an extensive outflow survey in the Orion Molecular Cloud -2 and -3 region. Our survey, which includes 41 potential star-forming sites, has been newly compiled using multi-wavelength data based on millimeter- and submillimeter-continuum observations as well as radio continuum observations. From the CO (3-2) observations performed with the ASTE 10 m telescope, we detected 14 CO molecular outflows, seven of which were newly identified. This higher detection rate, as compared to previous CO (1-0) results in the same region, suggests that CO (3-2) may be a better outflow tracer. Physical properties of these outflows and their possible driving sources were derived. Derived parameters were compared with those of CO outflows in low- and high-mass starforming regions. We show that the CO outflow momentum correlates with the bolometric luminosity of the driving source and with the envelope mass, regardless of the mass of the driving sources. In addition to these CO outflows, seven sources having NIR features suggestive of outflows were also identified.Comment: Accepted to Astrophysical Journal, high resolution images at http://www.asiaa.sinica.edu.tw/~satoko_t/papers/ms.ST.pd

    Pediatric Refugee Health Care Delivery in the Community Setting: An Educational Workshop for Multidisciplinary Family-Centered Care During Resettlement

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    Introduction: With 70.8 million people displaced worldwide, there is an increasing need for medical professionals to provide medical care to refugees. Insufficient training on refugee health poses a barrier to effective care delivery. Methods: This workshop addressed common challenges in providing family-centered pediatric refugee care in community settings as well as barriers related to policy changes. Presentations covered prearrival experiences, medical screening, and trauma-based care. In small groups, participants discussed cases that featured medical, behavioral health, social, and cultural factors impacting the provision of family-centered pediatric care that was culturally respectful and included shared decision-making. After the breakout session, each small group informed the larger group of topics discussed. Facilitators identified themes and reinforced key learning points. At the workshop\u27s conclusion, participants were guided to create their own personalized action plan. Results: This workshop was presented at two international conferences to more than 47 participants, including clinicians, nurse practitioners, pediatric residents, and medical students. Evaluations were completed by 34 individuals. Participants\u27 overall comfort level with taking care of refugee patients increased from 3.3 to 4.0 (on a 5-point scale, p = .24) during the 3-hour version of the workshop and from 3.8 to 4.0 (p = .43) in the 1-hour version of the workshop. Mean overall ratings of the 3- and 1-hour workshop versions on conference-administered evaluations were 4.8 and 4.2, respectively, on a 5-point scale. Discussions: This workshop was well received and equipped participants with knowledge, tools, and strategies regarding pediatric refugee health in a community setting

    Positional Coincidence of H2O Maser and a Plasma Obscuring Torus in Radio Galaxy NGC 1052

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    We present multi-frequency simultaneous VLBA observations at 15, 22 and 43 GHz towards the nucleus of the nearby radio galaxy NGC 1052. These three continuum images reveal a double-sided jet structure, whose relative intensity ratios imply that the jet axis is oriented close to the sky plane. The steeply rising spectra at 15-43 GHz at the inner edges of the jets strongly suggest that synchrotron emission is absorbed by foreground thermal plasma. We detected H2O maser emission in the velocity range of 1550-1850 km/s, which is redshifted by 50-350 km/s with respect to the systemic velocity of NGC 1052. The redshifted maser gas appears projected against both sides of the jet, in the same manner as the HI seen in absorption. The H2O maser gas are located where the free-free absorption opacity is large. This probably imply that the masers in NGC 1052 are associated with a circumnuclear torus or disk as in the nucleus of NGC 4258. Such circumnuclear structure can be the sence of accreting onto the central engine.Comment: 18 pages, 7 figures, accepted for publication in Ap

    Interferometric 12CO(J=2-1) image of the Nuclear Region of Seyfert 1 Galaxy NGC 1097

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    We have mapped the central region of the Seyfert 1 galaxy NGC 1097 in 12CO(J=2-1) with the Submillieter Array (SMA). The 12CO(J=2-1) map shows a central concentration and a surrounding ring, which coincide respectively with the Seyfert nucleus and a starburst ring. The line intensity peaks at the nucleus, whereas in a previously published 12CO(J=1-0) map the intensity peaks at the starburst ring. The molecular ring has an azimuthally averaged 12CO(J=2-1)/(J=1-0) intensity ratio (R21) of about unity, which is similar to those in nearby active star forming galaxies, suggesting that most of the molecular mass in the ring is involved in fueling the starburst. The molecular gas can last for only about 1.2\times10^8 years without further replenishment assuming a constant star formation rate and a perfect conversion of gas to stars. The velocity map shows that the central molecular gas is rotating with the molecular ring in the same direction, while its velocity gradient is much steeper than that of the ring. This velocity gradient of the central gas is similar to what is usually observed in some Seyfert 2 galaxies. To view the active nucleus directly in the optical, the central molecular gas structure can either be a low-inclined disk or torus but not too low to be less massive than the mass of the host galaxy itself, be a highly-inclined thin disk or clumpy and thick torus, or be an inner part of the galactic disk. The R21 value of ~1.9 of the central molecular gas component, which is significantly higher than the value found at the molecular gas ring, indicates that the activity of the Seyfert nucleus may have a significant influence on the conditions of the molecular gas in the central component.Comment: 22 pages, 4 figures, accepted by Ap

    Dynamical mass generation of a two-component fermion in Maxwell-Chern-Simons QED_3: The lowest ladder approximation

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    Dynamical mass generation of a two-component fermion in QED3QED_3 with a Chern-Simons term is investigated by solving the Schwinger-Dyson equation formulated in the lowest ladder approximation. Dependence of the dynamical fermion mass on a gauge-fixing parameter, a gauge coupling constant, and a topological mass is examined by approximated analytical and also numerical methods. The inclusion of the Chern-Simons term makes impossible to choose a peculiar gauge in which a wave function renormalization is absent. The numerical evaluation shows that the wave function renormalization is fairly close to 1 in the Landau gauge. It means that this gauge is still a specific gauge where the Ward-Takahashi identity is satisfied approximately. We also find that the dynamical mass is almost constant if the topological mass is larger than the coupling constant, while it decreases when the topological mass is comparable to or smaller than the coupling constant and tends to the value in QED3QED_3 without the Chern-Simons term.Comment: 22 pages, 9 figures, Version to appear in Phys. Rev.
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