Papers by Josh Walawender
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Astrophysical Journal, 2010
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Revista Mexicana De Astronomia Y Astrofisica, 2010
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Astronomical Journal, 2005
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Astronomical Journal, 2005
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Astronomical Journal, 2007
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We propose to search for new irradiated jets and protostellar outflows, shocks, protoplanetary di... more We propose to search for new irradiated jets and protostellar outflows, shocks, protoplanetary disks seen in silhouette (dark proplyds), and photo-ablating disks (bright proplyds), in the Carina Nebula with narrow-band filters and the MOSAIC camera on the CTIO 4 meter. Pilot observations obtained last December have demonstrated that this region contains a rich harvest of disks and outflows. A complete MOSAIC survey is needed to determine their population. The Carina Nebula is the most massive star forming region with the largest population of early O stars in which circumstellar disks, irradiated jets, and protostellar jets (Herbig-Haro objects) have so far been found. This is because Carina is much closer to us than other clusters with comparable populations of massive stars. These observations will extend our understanding of low-mass star formation, outflow production and impacts on the surrounding medium, and protoplanetary disk survival - to regions where the most massive stars are born. A detailed investigation of the Carina Nebula will provide a fundamental stepping stone to understanding how these processes operate in luminous H II region complexes in our Galaxy, the LMC and SMC, and in other galaxies.
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We propose to probe the line emission from nearby star forming regions in the 5 to 37 micron spec... more We propose to probe the line emission from nearby star forming regions in the 5 to 37 micron spectral range using the slit-scan mode of IRS. Our goals are: [1] Measure the fluxes produced by the pure rotational lines of molecular hydrogen and other spectral features in the 5 to 38 micrometer region from the surroundings of 4 well-studied and nearby outflow sources. [2] Trace the intermediate velocity (2 to 30 km/sec) shocks in outflow regions. Such emission is predicted by models in which high velocity motions traced by optical and near-IR emission lines (Herbig-Haro objects) accelerate molecular outflows and degrade into turbulent motions. We will obtain slit-scan maps in the LL and SL modes of IRS of arc-minute scale regions surrounding HH 211, HH212, L1448c and, NGC 2071. By observing these four sources, we will compare the mid-IR emission lines produced by regions supporting various levels of star formation activity ranging from the birth of isolated single stars, to small groups, to rich clusters containing over 100 YSOs and stars as massive as 8 to 10 Solar masses.
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Astronomical Journal, 2009
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Astrophysical Journal Supplement Series, 2010
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Astronomical Journal, 2006
We present a survey of shocks and outflows in the Chamaeleon I star-forming complex using Hα, [S ... more We present a survey of shocks and outflows in the Chamaeleon I star-forming complex using Hα, [S II], and SDSS i' images obtained from the ground, an i' image obtained with the Hubble Space Telescope, and 4.5 μm images obtained with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We find new Herbig-Haro (HH) objects and extensions to the previously cataloged shocks that trace parts of at least 20 distinct outflows from young stars. Some HH objects mark the presence of giant outflows, the largest of which is powered by Cha-MMS1 and associated with HH 49/50 near the Ced 110 region. Other large flows are powered by Cha-MMS2 in the Ced 112 region and the IRN in the Ced 111 region. Although some shocks exhibit infrared emission in the IRAC bands, most notably HH 49/50 (the ``tornado''), most outflows in the Cha I clouds are not detected in the Spitzer IRAC bands. This result is consistent with the general lack of extensive 2.12 μm H2 emission from Cha I.
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Astronomical Journal, 2004
... A NEW GIANT HERBIG-HARO FLOW IN L1451 Josh Walawender, 1,2 John Bally, 1,2 Bo Reipurth, 3 and... more ... A NEW GIANT HERBIG-HARO FLOW IN L1451 Josh Walawender, 1,2 John Bally, 1,2 Bo Reipurth, 3 and Colin Aspin 4 ... The flow is driven by the Class I protostar IRAS 03235+3004 embedded in a bright-rimmed, sharp-edged cometary cloud facing northeast. ...
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Astronomical Journal, 2005
... Josh Walawender, 1, 2 John Bally, 1, 2 Helen Kirk, 3, 4 and Doug Johnstone 3, 4 ... To minimi... more ... Josh Walawender, 1, 2 John Bally, 1, 2 Helen Kirk, 3, 4 and Doug Johnstone 3, 4 ... To minimize negative ''bowling'' around bright sources, all points with values outside of Æ5 times the mean noise per pixel were set to those values before convolution. ...
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Astronomical Journal, 2009
New observations of protostellar outflows associated with young stars in two of Orion's outlying ... more New observations of protostellar outflows associated with young stars in two of Orion's outlying cometary clouds, L1622 and L1634, are presented. The Hα surface brightness of the bright rims are used to argue that both clouds are located at a distance of about 400 pc in the interior of the Orion superbubble where they are illuminated by Orion's massive stars. Spitzer IRAC and MIPS images reveal 28 candidate young stellar objects (YSOs). Combined with the 14 spectroscopically confirmed T Tauri stars, there are at least 34 YSOs in L1622. Narrow-band images have led to the identification of about a dozen shock complexes in L1622. At least six belong to a highly collimated externally irradiated, bipolar jet, HH 963, that is powered by a low-luminosity Class II YSO located outside the projected edge of the L1622 dark cloud. However, the sources of most shocks remain unclear. The Spitzer/IRAC images reveal a compact, highly obscured, S-symmetric outflow brightest in the 4.5 μm images. A faint [S II] counter part, HH 962, is associated with the western end of this flow which appears to be powered by an obscured source in the L1622 cloud interior. The currently identified sample of YSOs implies a star formation efficiency of about 4% for L1622. The L1634 cloud contains nine YSOs and three outflows, including the well known HH 240/241 system. A new flow, HH 979, is powered by the embedded YSO IRS7 in L1634 and crosses the eastern lobe of the HH 240 outflow. Spitzer/IRAC images show 4.5 μm emission indicating molecular shocks from the Herbig-Haro objects closest to IRS 7. A YSO embedded in a condensation located 5' north of HH 240/241 is identified in the Spitzer images. This source drives an irradiated outflow, HH 980, whose lobes emerge into the ionized environment of the Orion-Eridanus superbubble interior. The star formation efficiency of L1634 is estimated to be about 3%.
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Astronomical Journal, 2010
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Astronomical Journal, 2006
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Astrophysical Journal Supplement Series, 2011
We present the Bolocam Galactic Plane Survey (BGPS), a 1.1 mm continuum survey at 33'' effective ... more We present the Bolocam Galactic Plane Survey (BGPS), a 1.1 mm continuum survey at 33'' effective resolution of 170 deg2 of the Galactic Plane visible from the northern hemisphere. The BGPS is one of the first large area, systematic surveys of the Galactic Plane in the millimeter continuum without pre-selected targets. The survey is contiguous over the range -10.5 <= l <= 90.5, |b| <= 0.5. Toward the Cygnus X spiral arm, the coverage was flared to |b| <= 1.5 for 75.5 <= l <= 87.5. In addition, cross-cuts to |b| <= 1.5 were made at l= 3, 15, 30, and 31. The total area of this section is 133 deg2. With the exception of the increase in latitude, no pre-selection criteria were applied to the coverage in this region. In addition to the contiguous region, four targeted regions in the outer Galaxy were observed: IC1396 (9 deg2, 97.5 <= l <= 100.5, 2.25 <= b <= 5.25), a region toward the Perseus Arm (4 deg2 centered on l = 111, b = 0 near NGC 7538), W3/4/5 (18 deg2, 132.5 <= l <= 138.5), and Gem OB1 (6 deg2, 187.5 <= l <= 193.5). The survey has detected approximately 8400 clumps over the entire area to a limiting non-uniform 1σ noise level in the range 11-53 mJy beam-1 in the inner Galaxy. The BGPS source catalog is presented in a previously published companion paper. This paper details the survey observations and data reduction methods for the images. We discuss in detail the determination of astrometric and flux density calibration uncertainties and compare our results to the literature. Data processing algorithms that separate astronomical signals from time-variable atmospheric fluctuations in the data timestream are presented. These algorithms reproduce the structure of the astronomical sky over a limited range of angular scales and produce artifacts in the vicinity of bright sources. Based on simulations, we find that extended emission on scales larger than about 5farcm9 is nearly completely attenuated (>90%) and the linear scale at which the attenuation reaches 50% is 3farcm8. Comparison with other millimeter-wave data sets implies a possible systematic offset in flux calibration, for which no cause has been discovered. This presentation serves as a companion and guide to the public data release (http://irsa.ipac.caltech.edu/Missions/bolocam.html) through NASA's Infrared Processing and Analysis Center (IPAC) Infrared Science Archive (IRSA). New data releases will be provided through IPAC-IRSA with any future improvements in the reduction. The BGPS provides a complementary long-wavelength spectral band for the ongoing ATLASGAL and Herschel-SPIRE surveys, and an important database and context for imminent observations with SCUBA-2 and ALMA.
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Astrophysical Journal, 2010
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Papers by Josh Walawender