<i>Herschel</i>observations of the hydroxyl radical (OH) in young stellar objects

Wampfler, S. F.; Herczeg, Gregory J.; Bruderer, S.; Benz, A. O.; Dishoeck, E. F. van; Kristensen, L. E.; Visser, R.; Doty, S. D.; Melchior, M.; Kempen, T. A. van; Yıldız, U. A.; Dedes, C.; Goicoechea, J. R.; Baudry, A.; Melnick, Gary J.; Bachiller, R.; Benedettini, M.; Bergin, Edwin A.; Bjerkeli, P.; Blake, Geoffrey A.; Bontemps, Sylvain; Braine, J.; Caselli, P.; Cernicharo, J.; Codella, C.; Daniel, F.; Giorgio, A. M. Di; Dominik, C.; Encrenaz, P.; Fich, M.; Fuente, A.; Giannini, T.; Graauw, Th. de; Helmich, Frank; Herpin, Fabrice; Hogerheijde, M. R.; Jacq, T.; Johnstone, Doug; Jørgensen, J. K.; Larsson, Bengt; Lis, D. C.; Liseau, R.; Marseille, M.; Coey, C. Mc; Neufeld, David A.; Nisini, B.; Olberg, M.; Parise, B.; Pearson, John C.; Plume, R.; Risacher, C.; Santiago-García, J.; Saraceno, P.; Shipman, R.; Tafalla, M.; Tak, van der Floris; Wyrowski, F.; Roelfsema, Pieter; Jellema, Willem; Dieleman, P.; Caux, E.; Stutzki, J.

doi:10.1051/0004-6361/201015112

Cited by 32 publications

(19 citation statements)

References 31 publications

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“…The low observed 63/146 µm flux ratio is difficult to reproduce using single-component excitation models (Liseau et al 2006), and is at variance with the values of ∼ 20 typically observed in YSOs using Her-schel (e.g. Wampfler et al 2010). Self-absorption of the 63 µm line in tenuous foreground gas was hypothesized by Liseau et al (2006) as a possible explanation for such anomalously low ratios, which seems plausible given the likely presence of diffuse/translucent gas along the line of sight to IRAS 19312+1950, which passes through the Galactic plane (see Section 3.5).…”

Section: O I Linesmentioning

confidence: 68%

ON THE NATURE OF THE ENIGMATIC OBJECT IRAS 19312+1950: A RARE PHASE OF MASSIVE STAR FORMATION?^∗

Cordiner

Boogert

Charnley

et al. 2016

ApJ

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IRAS 19312+1950 is a peculiar object that has eluded firm characterization since its discovery, with combined maser properties similar to an evolved star and a young stellar object (YSO). To help determine its true nature, we obtained infrared spectra of IRAS 19312+1950 in the range 5-550 µm using the Herschel and Spitzer space observatories. The Herschel PACS maps exhibit a compact, slightly asymmetric continuum source at 170 µm, indicative of a large, dusty circumstellar envelope. The far-IR CO emission line spectrum reveals two gas temperature components: ≈ 0.22M of material at 280 ± 18 K, and ≈ 1.6M of material at 157 ± 3 K. The O I 63 µm line is detected on-source but no significant emission from atomic ions was found. The HIFI observations display shocked, high-velocity gas with outflow speeds up to 90 km s −1 along the line of sight. From Spitzer spectroscopy, we identify ice absorption bands due to H 2 O at 5.8 µm and CO 2 at 15 µm. The spectral energy distribution is consistent with a massive, luminous (∼ 2 × 10 4 L ) central source surrounded by a dense, warm circumstellar disk and envelope of total mass ∼ 500-700M , with large bipolar outflow cavities. The combination of distinctive far-IR spectral features suggest that IRAS 19312+1950 should be classified as an accreting high-mass YSO rather than an evolved star. In light of this reclassification, IRAS 19312+1950 becomes only the 5th high-mass protostar known to exhibit SiO maser activity, and demonstrates that 18 cm OH maser line ratios may not be reliable observational discriminators between evolved stars and YSOs.

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Section: O I Linesmentioning

confidence: 68%

ON THE NATURE OF THE ENIGMATIC OBJECT IRAS 19312+1950: A RARE PHASE OF MASSIVE STAR FORMATION?^∗

Cordiner

Boogert

Charnley

et al. 2016

ApJ

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“…WISH has also observed specific [O I] CO, H 2 O and OH lines with PACS in the line observing mode for 8 of the 30 DIGIT sources (van Kempen et al 2010b;Wampfler et al 2010Wampfler et al , 2013. These data sample only a small spectral window around a limited number of individual lines but with higher spectral sampling and somewhat higher sensitivity, which facilitates the detection of weak lines.…”

Section: The Samplementioning

confidence: 99%

EMBEDDED PROTOSTARS IN THE DUST, ICE, AND GAS IN TIME (DIGIT)HERSCHELKEY PROGRAM: CONTINUUM SEDs, AND AN INVENTORY OF CHARACTERISTIC FAR-INFRARED LINES FROM PACS SPECTROSCOPY

Green

Evans

Jørgensen

et al. 2013

ApJ

109

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We present 50-210 µm spectral scans of 30 Class 0/I protostellar sources, obtained with Herschel-PACS, and 0.5-1000 µm SEDs, as part of the Dust, Ice, and Gas in Time (DIGIT) Key Program. Some sources exhibit up to 75 H 2 O lines ranging in excitation energy from 100-2000 K, 12 transitions of OH, and CO rotational lines ranging from J = 14 → 13 up to J = 40 → 39. [O I] is detected in all but one source in the entire sample; among the sources with detectable [O I] are two Very Low Luminosity Objects (VeLLOs). The mean 63/145 µm [O I] flux ratio is 17.2 ± 9.2. The [O I] 63 µm line correlates with L bol , but not with the time-averaged outflow rate derived from low-J CO maps.[C II] emission is in general not local to the source. The sample L bol increased by 1.25 (1.06) and T bol decreased to 0.96 (0.96) of mean (median) values with the inclusion of the Herschel data. Most CO rotational diagrams are characterized by two optically thin components ( N = (0.70 ± 1.12) × 10 49 total particles). N CO correlates strongly with L bol , but neither T rot nor N CO (warm)/N CO (hot) correlates with L bol , suggesting that the total excited gas is related to the current source luminosity, but that the excitation is primarily determined by the physics of the interaction (e.g., UV-heating/shocks). Rotational temperatures for H 2 O ( T rot = 194 ± 85 K) and OH ( T rot = 183 ± 117 K) are generally lower than for CO, and much of the scatter in the observations about the best fit is attributed to differences in excitation conditions and optical depths amongst the detected lines.

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“…APEX observations of higher CO transitions (up to 7-6) of a smaller area (80 × 80 ) surrounding the source show the molecular outflow gas reaches temperatures as high as 100 K (van Kempen et al 2009). Moreover, recent Herschel PACS observations of a region within 30 from the source reveal the existence of hot CO and H 2 O (thought to be partly produced by non-dissociative C-shocks) and OH and [OI] emission from dissociative J-shocks where the protostellar wind interacts with the surrounding dense core (van Kempen et al 2010;Wampfler et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Alma Observations of the Hh 46/47 Molecular Outflow

Arce

Mardones

Corder

et al. 2013

ApJ

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The morphology, kinematics and entrainment mechanism of the HH 46/47 molecular outflow were studied using new ALMA Cycle 0 observations. Results show that the blue and red lobes are strikingly different. We argue that these differences are partly due to contrasting ambient densities that result in different wind components having a distinct effect on the entrained gas in each lobe. A 29-point mosaic, covering the two lobes at an angular resolution of about 3 , detected outflow emission at much higher velocities than previous observations, resulting in significantly higher estimates of the outflow momentum and kinetic energy than previous studies of this source, using the CO(1-0) line. The morphology and the kinematics of the gas in the blue lobe are consistent with models of outflow entrainment by a wide-angle wind, and a simple model describes the observed structures in the position-velocity diagram and the velocity-integrated intensity maps. The red lobe exhibits a more complex structure, and there is evidence that this lobe is entrained by a wide-angle wind and a collimated episodic wind. Three major clumps along the outflow axis show velocity distribution consistent with prompt entrainment by different bow shocks formed by periodic mass ejection episodes which take place every few hundred years. Position-velocity cuts perpendicular to the outflow cavity show gradients where the velocity increases towards the outflow axis, inconsistent with outflow rotation. Additionally, we find evidence for the existence of a small outflow driven by a binary companion.

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Herschelobservations of the hydroxyl radical (OH) in young stellar objects

Cited by 32 publications

References 31 publications

ON THE NATURE OF THE ENIGMATIC OBJECT IRAS 19312+1950: A RARE PHASE OF MASSIVE STAR FORMATION?^∗

ON THE NATURE OF THE ENIGMATIC OBJECT IRAS 19312+1950: A RARE PHASE OF MASSIVE STAR FORMATION?^∗

EMBEDDED PROTOSTARS IN THE DUST, ICE, AND GAS IN TIME (DIGIT)HERSCHELKEY PROGRAM: CONTINUUM SEDs, AND AN INVENTORY OF CHARACTERISTIC FAR-INFRARED LINES FROM PACS SPECTROSCOPY

Alma Observations of the Hh 46/47 Molecular Outflow

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Herschelobservations of the hydroxyl radical (OH) in young stellar objects

Cited by 32 publications

References 31 publications

ON THE NATURE OF THE ENIGMATIC OBJECT IRAS 19312+1950: A RARE PHASE OF MASSIVE STAR FORMATION?∗

ON THE NATURE OF THE ENIGMATIC OBJECT IRAS 19312+1950: A RARE PHASE OF MASSIVE STAR FORMATION?∗

EMBEDDED PROTOSTARS IN THE DUST, ICE, AND GAS IN TIME (DIGIT)HERSCHELKEY PROGRAM: CONTINUUM SEDs, AND AN INVENTORY OF CHARACTERISTIC FAR-INFRARED LINES FROM PACS SPECTROSCOPY

Alma Observations of the Hh 46/47 Molecular Outflow

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Resources

About

ON THE NATURE OF THE ENIGMATIC OBJECT IRAS 19312+1950: A RARE PHASE OF MASSIVE STAR FORMATION?^∗

ON THE NATURE OF THE ENIGMATIC OBJECT IRAS 19312+1950: A RARE PHASE OF MASSIVE STAR FORMATION?^∗