The constancy of the ratio of the molecular hydrogen lines at 3.8  m in Orion

Brand, P. W. J. L.; Toner, M. P.; Geballe, T. R.; Webster, Adrian; Williams, P. M.; Burton, M. G.

doi:10.1093/mnras/236.4.929

Cited by 50 publications

(39 citation statements)

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“…As has previously been shown (e.g. Brand et al 1988Brand et al , 1989Moorhouse et al 1990) H 2 excitation of the v = 3 and 4 levels cannot be reproduced by C-type shock models. Therefore part of the excitation mechanism may be due to PDR excitation and/or J-type shocks .…”

Section: C-versus J-type Shockmentioning

confidence: 71%

Observational 2D model of H₂emission from a bow shock in the Orion Molecular Cloud

Kristensen¹,

Ravkilde

Forêts

et al. 2007

A&A

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Aims. We present a new method for reproducing high spatial resolution observations of bow shocks by using 1D plane parallel shock models. As an example we analyse one bow shock located in the Orion Molecular Cloud (OMC1). Methods. We use high spatial resolution near-infrared observations of H 2 rovibrational emission to constrain shock models. These observations have been made at the ESO-VLT using a combination of the NACO adaptive optics system and infrared camera array and the Fabry-Perot interferometer. Three rovibrational H 2 lines have been observed: v = 1−0 S(1) at 2.12 µm, v = 1−0 S(0) at 2.23 µm and v = 2−1 S(1) at 2.25 µm. The spatial resolution is 0. 15 ∼ 70 AU. We analyse a single bow shock located in our field, featuring a very well defined morphology and high brightness. Results. One dimensional shock models are combined to estimate the physical properties of pre-shock density, shock velocity and transverse magnetic field strength along the bow shock. We find that the pre-shock density is constant at ∼5 × 10 5 cm −3 and shock velocities lie between ∼35 km s −1 in the wings of the shock and ∼50 km s −1 at the apex. We also find that the transverse magnetic field is stronger at the apex and weaker further down the wings varying between ∼2 and 4 mGauss. Predictions of shock velocity and magnetic field strength agree with previous independent observations.

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Section: C-versus J-type Shockmentioning

confidence: 71%

Observational 2D model of H₂emission from a bow shock in the Orion Molecular Cloud

Kristensen¹,

Ravkilde

Forêts

et al. 2007

A&A

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“…The measured ratios of 2-1S(1)/1-0S(1) and 1-0S(2)/1-0S(0) (see Fig. 26) imply that shock (J-shock model from Brand et al 1989) and X-ray excitation are favored, which we investigate in more detail in the following. We used the models of Maloney et al (1996) to compare observed and predicted 1−0S(1), 2−1S(1) and [FeII]λ 1.644 μm fluxes in XDRs.…”

Section: Column Densities and Population Density Diagrammentioning

confidence: 87%

Near-infrared imaging spectroscopy of the inner few arcseconds of NGC 4151 with OSIRIS at Keck

Iserlohe¹,

Krabbe²,

Larkin³

et al. 2013

A&A

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We present H-and K-band data from the inner arcsecond of the Seyfert 1.5 galaxy NGC 4151 obtained with the adaptive-opticsassisted near-infrared-imaging field spectrograph OSIRIS at the Keck Observatory. The angular resolution is about a few parsecs on-site and thus competes easily with optical images taken previously with the Hubble Space Telescope. We present the morphology and dynamics of most species detected but focus on the morphology and dynamics of the narrow line region (as traced by emission of [FeII]λ1.644 μm), the interplay between plasma ejected from the nucleus (as traced by 21 cm continuum radio data) and hot H 2 gas and characterize the detected nuclear HeIλ2.058 μm absorption feature as a narrow absorption line (NAL) phenomenon. The emission from the narrow line region (NLR) as traced by [FeII] reveals a biconical morphology and we compare the measured dynamics in the [FeII] emission line with models that propose acceleration of gas in the NLR and simple ejection of gas into the NLR. In the inner 2.5 arcsec the acceleration model reveals a better fit to our data than the ejection model. We also see evidence that the jet very locally enhances emission in [FeII] at certain positions in our field-of-view such that we were able to distinct the kinematics of these clouds from clouds generally accelerated in the NLR. Further, the radio jet is aligned with the bicone surface rather than the bicone axis such that we assume that the jet is not the dominant mechanism responsible for driving the kinematics of clouds in the NLR. The hot H 2 gas is thermal with a temperature of about 1700 K. We observe a remarkable correlation between individual H 2 clouds at systemic velocity with the 21 cm continuum radio jet. We propose that the radio jet is at least partially embedded in the galactic disk of NGC 4151 such that deviations from a linear radio structure are invoked by interactions of jet plasma with H 2 clouds that are moving into the path of the jet because of rotation of the galactic disk of NGC 4151. Additionally, we observe a correlation of the jet as traced by the radio data, with gas as traced in Brγ and H 2 , at velocities between systemic and ±200 km s −1 at several locations along the path of the jet. The HeIλ2.058 μm line in NGC 4151 appears in emission with a blueshifted absorption component from an outflow. The emission (absorption) component has a velocity offset of 10 km s −1 (−280 km s −1 ) with a Gaussian (Lorentzian) full-width (half-width) at half maximum of 160 km s −1 (440 km s −1 ). The absorption component remains spatially unresolved and its kinematic measures differ from that of UV resonance absorption lines. From the amount of absorption we derive a lower limit of the HeI 2 1 S column density of 1 × 10 14 cm −2 with a covering factor along the line-of-sight of C los 0.1.

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“…Figure 8 (left) shows the diagnostic diagram with the H 2 line ratios 2-1S(1)/1-0S(1) vs. 1-0S(2)/1-0S(0) with the two chosen apertures in blue and red (see e.g., Mouri 1994;Zuther et al 2007;Mazzalay et al 2013b;Smajić et al 2014;Falcón-Barroso et al 2014). Furthermore, we indicate the positions of models for thermal UV excitation (Sternberg & Dalgarno 1989), UV fluorescence (Black & van Dishoeck 1987), X-ray heating (Draine & Woods 1990), shock-heating (Brand et al 1989), and a thermal emission curve. The position in the diagram shows that the H 2 excitation in the two apertures cannot be explained by thermal excitation alone.…”

Section: Emission Line Excitation Mechanismsmentioning

confidence: 99%

“…The location of thermal UV excitation (Sternberg & Dalgarno 1989) and non-thermal models (Black & van Dishoeck 1987), as well as the thermal emission curve from 1000 K to 3000 K, are plotted in gray. The X-ray heating models (Draine & Woods 1990) are marked by yellow triangles, the shock-heating model (Brand et al 1989) by a green circle. Right: diagnostic diagram with line ratios 1-0S (1) T vib ≈ T rot .…”

Section: Emission Line Excitation Mechanismsmentioning

confidence: 99%

A low-luminosity type-1 QSO sample

Busch

Smajić

Scharwächter

et al. 2015

A&A

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Circumnuclear star formation and active galactic nucleus (AGN) feedback is believed to play a critical role in galaxy evolution. The low-luminosity quasi-stellar object (LLQSO) sample that contains 99 of the closest AGN with redshift z ≤ 0.06 fills the gap between the local AGN population and high-redshift QSOs that is essential to understand the AGN evolution with redshift. In this paper, we present the results of the near-infrared H-and K-integral field spectroscopy of the inner kiloparsecs of the LLQSO HE 1029-1831 with SINFONI. Line maps show that ionized hydrogen gas is located in spiral arms within the stellar bar and in a circumnuclear ring. Line fluxes and diagnostic line ratios indicate recent or ongoing star formation in the circumnuclear region and the presence of young and intermediate-age stellar populations in the bulge. In particular, we find traces of an intense starburst in the circumnuclear region that has begun around 100 Myr ago but has declined to a fraction of the maximum intensity now. We estimate the dynamical bulge mass and find that the galaxy follows published M BH −M bulge relations. However, bulge-disk decomposition of the K-band image with B reveals that HE 1029-1831 does not follow the M BH −L bulge relations of inactive galaxies. We conclude that the deviation from M BH −L bulge relations of inactive galaxies in this source is instead caused by young stellar populations and not by an undermassive black hole.

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The constancy of the ratio of the molecular hydrogen lines at 3.8 m in Orion

Cited by 50 publications

References 0 publications

Observational 2D model of H₂emission from a bow shock in the Orion Molecular Cloud

Observational 2D model of H₂emission from a bow shock in the Orion Molecular Cloud

Near-infrared imaging spectroscopy of the inner few arcseconds of NGC 4151 with OSIRIS at Keck

A low-luminosity type-1 QSO sample

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The constancy of the ratio of the molecular hydrogen lines at 3.8 m in Orion

Cited by 50 publications

References 0 publications

Observational 2D model of H2emission from a bow shock in the Orion Molecular Cloud

Observational 2D model of H2emission from a bow shock in the Orion Molecular Cloud

Near-infrared imaging spectroscopy of the inner few arcseconds of NGC 4151 with OSIRIS at Keck

A low-luminosity type-1 QSO sample

Contact Info

Product

Resources

About

Observational 2D model of H₂emission from a bow shock in the Orion Molecular Cloud

Observational 2D model of H₂emission from a bow shock in the Orion Molecular Cloud