<i>Herschel</i>observations of the Herbig-Haro objects HH 52-54

Bjerkeli, P.; Liseau, R.; Nisini, B.; Tafalla, M.; Benedettini, M.; Bergman, P.; Dionatos, O.; Giannini, T.; Herczeg, Gregory J.; Justtanont, K.; Larsson, Bengt; MCoey, C.; Olberg, M.; Olofsson, A. O. H.

doi:10.1051/0004-6361/201116846

Cited by 23 publications

(48 citation statements)

References 45 publications

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“…The kinetic temperatures generally inferred by those studies for the outflow components are in the range 100-200 K (Yıldız et al 2010;Bjerkeli et al 2011). These values are similar to our lower limits.…”

Section: Discussion: Physical Conditionssupporting

confidence: 91%

High-JCO emission in the Cepheus E protostellar outflow observed with SOFIA/GREAT

Gómez-Ruiz¹,

Leurini²,

Codella³

et al. 2012

A&A

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Context. Owing to the high energy required for their excitation, high-J CO transitions are a valuable tool for the study of protostellar jets and outflows. However, high spectral resolution observations of high-J CO lines, which are essential to distinguish the different components in the line profiles, were impossible until the start of operations of the Herschel Space Observatory and the Stratospheric Observatory For Infrared Astronomy (SOFIA).Aims. We present and analyze two spectrally resolved high-J CO lines toward a protostellar outflow. We study the physical conditions, as a function of velocity, traced by such high-energy transitions in bipolar outflows. Methods. We selected the molecular outflow Cep E, driven by an intermediate-mass class 0 protostar. Using the German REceiver for Astronomy at Terahertz frequencies (GREAT) onboard SOFIA, we observed the CO (12-11) and (13-12) transitions (E u ∼ 430 and 500 K, respectively) toward one position in the blue lobe of this outflow, that had been known to display high-velocity molecular emission. Results. We detect the outflow emission in both transitions, up to extremely high velocities (∼100 km s −1 with respect to the systemic velocity). We divide the line profiles into three velocity ranges that each have interesting spectral features: standard, intermediate, and extremely high-velocity. One distinct bullet is detected in each of the last two. A large velocity gradient analysis for these three velocity ranges provides constraints on the kinetic temperature and volume density of the emitting gas, 100 K and 10 4 cm −3 , respectively. These results are in agreement with previous ISO observations and are comparable with results obtained by Herschel for similar objects. Conclusions. High-J CO lines are a good tracer of molecular bullets in protostellar outflows. Our analysis suggests that different physical conditions are at work in the intermediate velocity range compared with the standard and extremely high-velocity gas.

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Section: Discussion: Physical Conditionssupporting

confidence: 91%

High-JCO emission in the Cepheus E protostellar outflow observed with SOFIA/GREAT

Gómez-Ruiz¹,

Leurini²,

Codella³

et al. 2012

A&A

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“…Among them, recent examples that include Herschel high-J CO and groundbased mid-J CO observations are the low-mass outflows HH46 and HH52-54 (van Kempen et al 2010b;Bjerkeli et al 2011). In both cases the CO SLEDs are fitted with at least two different components, although the fitted physical parameters are slightly different from our results for L1448 and HH211 (e.g., higher temperatures found in L1448/HH211 than in HH52-54).…”

Section: Spectral Line Energy Distribution (Sled)contrasting

confidence: 81%

Warm gas in protostellar outflows

Gómez-Ruiz

Wyrowski

Leurini

et al. 2013

A&A

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Context. Observations of CO rotational transitions in the 0.3−0.4 millimeter range, now possible from exceptional sites on the ground, provide the opportunity of studying the warm component of molecular outflows in star-forming regions. Aims. This study aims to characterize the role of the warm gas in high-velocity and collimated outflows from Class 0 low-mass protostars. Methods. We used the CHAMP + heterodyne array on the APEX telescope to map the CO (6-5) and CO (7-6) emission in the wellknown Class 0 outflows L1448-mm and HH211-mm. We complement these data with 13 CO (6-5) observations and also with previous low-J CO observations. Results. The CO (6-5) and (7-6) emission was detected to be tracing the outflow lobes. In L1448, extremely high-velocity (EHV) emission was detected in both transitions. In HH211, high-velocity CO (6-5) emission was detected to be tracing the regions close to the central object, but it was also found close to the bow-shock regions seen in the mid-IR. A large velocity gradient code applied to these and the complementary low-J CO data revealed the high-velocity components to be dense (>10 5 cm −3 ) and warm (T > 200 K) gas, in agreement with previous observations of shock tracers such as SiO. Conclusions. The high-velocity emission of these mid-J CO transitions are very good tracers of the inner highly excited part of outflows, which possibly is molecular material related to the underlying jet. In addition, these transitions are also strong at the bowshock positions, which make them a good tool for probing these environments.

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“…The antenna temperature scale, T * A , was converted into the main-beam temperature scale, T mb , using main-beam efficiency factor of 0.71 (Roelfsema et al 2012). The flux calibration uncertainty is around 10%, based on cross-calibration with Herschel/PACS (Bjerkeli et al 2011). At the velocity resolution of 1 km s −1 , the rms noise is 80 mK (T mb scale).…”

Section: Herschel/hifi Observationsmentioning

confidence: 99%

“…The beam sizes of Herschel H 2 O (2 12 −1 01 ) (magenta circle), CO (15−14) (green, Bjerkeli et al 2014), and SEST CO (2−1) (black, Bjerkeli et al 2009Bjerkeli et al , 2011 are displayed. Offsets are relative to: α J2000 = 12 h 55 m 50. s 3, δ J2000 = −76 • 56 23 (Bjerkeli et al 2011). Lower: Spitzer/IRS H 2 0−0 S(4) image of HH 54 (Neufeld et al 2006).…”

Section: Visir High-resolution Mid-ir Spectroscopymentioning

confidence: 99%

“…Knee (1992) associates HH 54 with a monopolar blue-shifted CO outflow, whose driving source remains unclear (e.g. Caratti o Garatti et al 2006;Ybarra & Lada 2009;Bjerkeli et al 2011). Mid-IR cooling is dominated by pure rotational H 2 lines (Cabrit et al 1999;Giannini et al 2006;Neufeld et al 1998Neufeld et al , 2006 probing warm gas with a mixture of temperatures in the range 400−1200 K. HH 54 was also observed in several lines of CO and H 2 O from space and the ground (Liseau et al 1996;Nisini et al 1996;Bjerkeli et al 2009Bjerkeli et al , 2011.…”

Section: Introductionmentioning

confidence: 99%

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First spectrally-resolved H₂observations towards HH 54

Santangelo

Antoniucci

Nisini

et al. 2014

A&A

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Context. Herschel observations suggest that the H 2 O distribution in outflows from low-mass stars resembles the H 2 emission. It is still unclear which of the different excitation components that characterise the mid-and near-IR H 2 distribution is associated with H 2 O. Aims. The aim is to spectrally resolve the different excitation components observed in the H 2 emission. This will allow us to identify the H 2 counterpart associated with H 2 O and finally derive directly an H 2 O abundance estimate with respect to H 2 . Methods. We present new high spectral resolution observations of H 2 0−0 S(4), 0−0 S(9), and 1−0 S(1) towards HH 54, a bright nearby shock region in the southern sky. In addition, new Herschel/HIFI H 2 O (2 12 −1 01 ) observations at 1670 GHz are presented. Results. Our observations show for the first time a clear separation in velocity of the different H 2 lines: the 0−0 S(4) line at the lowest excitation peaks at −7 km s −1 , while the more excited 0−0 S(9) and 1−0 S(1) lines peak at −15 km s −1 . H 2 O and high-J CO appear to be associated with the H 2 0−0 S(4) emission, which traces a gas component with a temperature of 700−1000 K. The H 2 O abundance with respect to H 2 0−0 S(4) is estimated to be X(H 2 O) < 1.4 × 10 −5 in the shocked gas over an area of 13 . Conclusions. We resolve two distinct gas components associated with the HH 54 shock region at different velocities and excitations. This allows us to constrain the temperature of the H 2 O emitting gas (≤1000 K) and to derive correct estimates of H 2 O abundance in the shocked gas, which is lower than what is expected from shock model predictions.

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Herschelobservations of the Herbig-Haro objects HH 52-54

Cited by 23 publications

References 45 publications

High-JCO emission in the Cepheus E protostellar outflow observed with SOFIA/GREAT

High-JCO emission in the Cepheus E protostellar outflow observed with SOFIA/GREAT

Warm gas in protostellar outflows

First spectrally-resolved H₂observations towards HH 54

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Herschelobservations of the Herbig-Haro objects HH 52-54

Cited by 23 publications

References 45 publications

High-JCO emission in the Cepheus E protostellar outflow observed with SOFIA/GREAT

High-JCO emission in the Cepheus E protostellar outflow observed with SOFIA/GREAT

Warm gas in protostellar outflows

First spectrally-resolved H2observations towards HH 54

Contact Info

Product

Resources

About

First spectrally-resolved H₂observations towards HH 54