A combined optical/infrared spectral  diagnostic analysis of the
HH1 jet

Nisini, B.; Bacciotti, F.; Giannini, T.; Massi, F.; Eislöffel, J.; Podio, L.; Ray, T. P.

doi:10.1051/0004-6361:20053097

Cited by 116 publications

(219 citation statements)

References 43 publications

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“…Several HH jets have been investigated on larger scales using ground-based telescopes (BE99; Podio et al 2006;Nisini et al 2005). The hydrogen density of knots in these jets is generally found to be between 600 and 6 × 10 4 cm −3 , that is one to three orders of magnitude lower than what we measure in the first arcseconds of the RW Aur jet.…”

Section: Comparison With Other Young Stellar Jetsmentioning

confidence: 49%

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HST/STIS observations of the RW Aurigae bipolar jet: mapping the physical parameters close to the source

Melnikov

Eislöffel²,

Bacciotti

et al. 2009

A&A

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111

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Context. We present the results of new spectral diagnostic investigations applied to high-resolution long-slit spectra obtained with the Hubble Space Telescope Imaging Spectrograph (HST/STIS) of the jet from the T Tauri star RW Aur. Aims. Our primary goal is to determine basic physical parameters (electron density n e and electron temperature T e , hydrogen ionisation fraction x e , total hydrogen density n H , radial velocity v r and the mass outflow rateṀ j ) along both the red-and blueshifted lobes of the RW Aur jet. Methods. The input dataset consists of seven long-slit spectra, of 0. 1 spatial resolution, taken with the STIS slit parallel to the jet, and stepped across it. We use the Bacciotti & Eislöffel (1999, A&A, 342, 717) Results. We were able to extract the parameters as far as 3. 9 in the red-and 2. 1 in the blueshifted beam. The electron density at the base of both lobes is close to the critical density for [S II] emission but then it decreases gradually with distance from the source. The range of electron temperatures derived for this jet (T e = 10 4 −2 × 10 4 K) is similar to those generally found in other outflows from young stars. The ionisation fraction x e varies between 0.04 and 0.4, increasing within the first few arcseconds and then decreasing in both lobes. The total hydrogen density, derived as n H = n e /x e , is on average 3.2 × 10 4 cm −3 and shows a gradual decrease along the beam. Variations of the above quantities along the jet lobes appear to be correlated with the position of knots. Combining the derived parameters with v r measured from the HST spectra and other characteristics available for this jet, we estimateṀ j following two different procedures. The mass-outflow rateṀ j is moderate and similar in the two lobes, despite the fact that the well-known asymmetry in the radial velocity persists close to the source. Using the results of the BE diagnostics we find averages along the first 2. 1 of both flows (a region presumably not yet affected by interaction with the jet environment) of 2.6 × 10 −9 M yr −1 for the red lobe and 2.0 × 10 −9 M yr −1 for the blueshifted flow, with an uncertainty of ±log M = 1.6. Conclusions. The fact that the derived mass outflow rate is similar in the two lobes appears to indicate that the central engine is constrained on the two sides of the system and that the observed asymmetries are due to environmental conditions. Possible suggestions for the origin of the differences are discussed. The RW Aur jet appears to be the second densest outflow from a T Tauri star studied so far, but its other properties are quite similar to those found in other jets from young stars, suggesting that a common acceleration mechanism operates in these sources.

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Section: Comparison With Other Young Stellar Jetsmentioning

confidence: 49%

“…Here we present a new, more detailed determination of theṀ j distribution along both jet lobes, exploiting two different methods described in and Nisini et al (2005).…”

Section: Mass Outflow Ratementioning

confidence: 99%

HST/STIS observations of the RW Aurigae bipolar jet: mapping the physical parameters close to the source

Melnikov

Eislöffel²,

Bacciotti

et al. 2009

A&A

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111

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“…When dust grains evaporate in the launching region or are sputtered in shocks along the jet, these species are released into the gas-phase (Jones et al 1994;Jones 2000;May et al 2000;Draine 2004;Guillet et al 2009Guillet et al , 2011. Gas phase depletion of refractory elements has been observed by Nisini et al (2005) and Podio et al (2006Podio et al ( , 2009Podio et al ( , 2011 in HH jets from Class I sources at large distances from their driving source. It has also been observed in the inner 100 au of a CTTS jet (Agra-Amboage et al 2011).…”

Section: Dust Contentmentioning

confidence: 99%

“…We assume that Fe and S are singly ionized and use the 16-levels model presented in Nisini et al (2002Nisini et al ( , 2005 with collisional coefficients by Nussbaumer & Storey (1988) for Fe and by Keenan et al (1996) for S. For the [Ca ]/[S ] ratio, it is assumed that no neutral calcium is present, since its ionization potential is very low, 6.1 eV. For the ionization balance we consider three limiting cases:…”

Section: Dust Contentmentioning

confidence: 99%

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Ellerbroek

Podio

Dougados

et al. 2014

A&A

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131

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Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) spectra of the jet from the Herbig Ae star HD 163296, obtained with VLT/X-shooter. We determine the physical conditions in the knots and also their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ∼16 yr. The velocity dispersion versus jet velocity and the energy input are comparable between both lobes. However, the mass-loss rate, velocity, and shock conditions are asymmetric. We findṀ jet /Ṁ acc ∼ 0.01−0.1, which is consistent with magneto-centrifugal jet launching models. No evidence of any dust is found in the high-velocity jet, suggesting a launch region within the sublimation radius (<0.5 au). The jet inclination measured from proper motions and radial velocities confirms that it is perpendicular to the disk. A tentative relation is found between the structure of the jet and the photometric variability of the central source. Episodes of NIR brightening were previously detected and attributed to a dusty disk wind. We report for the first time significant optical fadings lasting from a few days up to a year, coinciding with the NIR brightenings. These are very likely caused by dust lifted high above the disk plane, and this supports the disk wind scenario. The disk wind is launched at a larger radius than the high-velocity atomic jet, although their outflow variability may have a common origin. No significant relation between outflow and accretion variability could be established. Our findings confirm that this source undergoes periodic ejection events, which may be coupled with dust ejections above the disk plane.

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“…This suggests that (1) most of the outflow material is transported by a cooler and denser component than traced by the near-IR H 2 lines, such as the H 2 pure rotational lines (Caratti o Garatti et al 2008); or (2) most of the H 2 has been dissociated, and the jet is mainly atomic. The latter has been observed in other Class I jets, where the measuredṀ H 2 is around one order of magnitude lower than measured from the [Fe ii] emission (Davis et al 2011;Nisini et al 2005). …”

Section: Accretion and Ejection Propertiesmentioning

confidence: 57%

Spatially resolved H₂emission from a very low-mass star

Lopez

Garatti

Weigelt

et al. 2013

A&A

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Context. Molecular outflows from very low-mass stars (VLMSs) and brown dwarfs have been studied very little. So far, only a few CO outflows have been observed, allowing us to map the immediate circumstellar environment. Aims. We present the first spatially resolved H 2 emission around IRS54 (YLW 52), a ∼0.1-0.2 M Class I source. Methods. By means of VLT SINFONI K-band observations, we probed the H 2 emission down to the first ∼50 AU from the source.Results. The molecular emission shows a complex structure delineating a large outflow cavity and an asymmetric molecular jet. Thanks to the detection of several H 2 transitions, we are able to estimate average values along the jet-like structure (from source position to knot D) of A V ∼ 28 mag, T ∼ 2000−3000 K, and H 2 column density N(H 2 ) ∼ 1.7 × 10 17 cm −2 . This allows us to estimate a mass loss rate of ∼2 × 10 −10 M yr −1 for the warm H 2 component. In addition, from the total flux of the Br γ line, we infer an accretion luminosity and mass accretion rate of 0.64 L and ∼3 × 10 −7 M yr −1 , respectively. The outflow structure is similar to those found in low-mass Class I and CTTS. However, the L acc /L bol ratio is very high (∼80%), and the mass accretion rate is about one order of magnitude higher when compared to objects of roughly the same mass, pointing to the young nature of the investigated source.

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A combined optical/infrared spectral diagnostic analysis of the HH1 jet

Cited by 116 publications

References 43 publications

HST/STIS observations of the RW Aurigae bipolar jet: mapping the physical parameters close to the source

HST/STIS observations of the RW Aurigae bipolar jet: mapping the physical parameters close to the source

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Spatially resolved H₂emission from a very low-mass star

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A combined optical/infrared spectral diagnostic analysis of the HH1 jet

Cited by 116 publications

References 43 publications

HST/STIS observations of the RW Aurigae bipolar jet: mapping the physical parameters close to the source

HST/STIS observations of the RW Aurigae bipolar jet: mapping the physical parameters close to the source

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Spatially resolved H2emission from a very low-mass star

Contact Info

Product

Resources

About

Spatially resolved H₂emission from a very low-mass star