Rotation of Jets from Young Stars: New Clues from the<i>Hubble Space Telescope</i>Imaging Spectrograph

Coffey, Deirdre; Bacciotti, F.; Woitas, J.; Ray, T. P.; Eislöffel, J.

doi:10.1086/382019

Cited by 185 publications

(263 citation statements)

References 15 publications

Supporting

Mentioning

225

Contrasting

Order By: Relevance

“…5 from the central source (about 200 AU at the distance of RW Aur). Similar signatures of rotation have been discovered in other jets from T Tauri stars Coffey et al 2004Coffey et al , 2007. Such observations support the magneto-centrifugal launching scenario for jets (cf Ferreira et al 2006;Pudritz et al 2007, and references therein), which predicts a transport of angular momentum from the disk to the jet by the accretion/ejection "engine".…”

Section: Introductionsupporting

confidence: 80%

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

111

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionsupporting

confidence: 80%

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

111

View full text Add to dashboard Cite

show abstract

“…Hughes et al (1994) noted that the very low luminosity of the star, to which a tentative spectral type K0: was assigned, seems to come from blocking of its direct light by an edge-on disk, consistent with the fast proper motion of the jet knots at the distance of Lupus 3 when compared to their radial velocities, which were previously determined by Graham & Heyer (1988). The base of the jet has been studied more recently with STIS at HST by Coffey et al (2004Coffey et al ( , 2007. The spectral energy distribution of Th 28 obtained with Spitzer (Chapman et al 2007, Merín et al 2008 shows a rising flux toward long wavelengths indicative of large amounts of warm dust, perhaps in the form of a massive circumstellar disk.…”

Section: Introductionmentioning

confidence: 63%

“…3 from Th 28 sampled by Coffey et al (2004Coffey et al ( , 2007Coffey et al ( , 2008 using STIS observations at the HST performed in June 2004, only one year after our UVES observation. Their analysis of ultraviolet and visible forbidden lines (Coffey et al 2008) allows them to derive average electron densities of 10 4 cm −3 , high electron temperatures (T e = 20 000 K), an ionization fraction x = 0.3, and an estimate of the mass outflow rate of 1.2 × 10 −8 M yr −1 .…”

Section: The Redshifted Outflowmentioning

confidence: 99%

High-resolution visible spectroscopy of the jet-driving star Th 28

Comerón¹,

Fernández²

2010

A&A

View full text Add to dashboard Cite

Context. We present a study of the extreme T Tauri star Th 28, a young stellar object in the Lupus 3 cloud whose spectrum displays all the varieties of signposts associated with early stellar activity. Th 28 is the driving source of a fast jet, making it a very promising target to study the disk-jet connection. Aims. We try to identify and investigate the different structural components that contribute to the different emission lines in the spectrum of the Th 28 central source. Methods. We obtained high-resolution visible spectroscopy with the UVES spectrograph at the VLT, using the resolved profiles of both permitted and forbidden lines as tracers of gas with different kinematic and physical properties, complemented with other observations from the literature. Results. We identify four distinct structural components that contribute to the visible emission-line spectrum of Th 28. The first one, dominating most of the permitted and forbidden lines, is probably associated with the origin of the outflow that in the past produced the Herbig-Haro objects seen to the west of Th 28. The second one is an uncollimated stellar wind characterized by high excitation and temperature, as shown by the broad profile of the intense [OIII] lines. The third component, traced only by permitted lines, appears as a redshifted tail extending up to radial velocities of +450 km s −1 , which we attribute to magnetospheric accretion. From the latter component we obtain a rough estimate of 0.6−0.9 M for the mass of the central object. Using published equivalent widths of the CaII triplet lines, we estimate an accretion rate of 4.2−6.3 × 10 −8 M yr −1 , comparable to the values inferred for other T Tauri stars of similar mass. The last component, which appears most clearly in the [SII] lines and is hardly seen in any lines other than those of [OI], displays signatures that we interpret as coming from rotation, perhaps formed in a disk atmosphere. Following this interpretation, we estimate a disk central hole of 0.7 AU radius. Conclusions. Even though spatially unresolved, the spectrum of Th 28 is rich in emission lines whose shapes provide important information on the distinct structures where they form. In this way we were able to identify the existence of a stellar wind, an accretion flow, the basis of a collimated outflow, and possibly a rotating disk atmosphere, obtaining rough estimates of basic parameters of the central source and its environment that should be useful for further modeling.

show abstract

“…It also maximises survey efficiency and avoids difficulties introduced by uneven slit illumination (Woitas et al 2005). Analysis in the optical and near UV consistently produced systematic radial velocities differences of typically 15−25 km s −1 close to the ejection point (Coffey et al 2004(Coffey et al , 2007. These very encouraging statistics led to a pilot study to detect gradients in younger Class I sources, since rotation signatures should be present at all evolutionary stages.…”

Section: Introductionmentioning

confidence: 80%

Searching for jet rotation in Class 0/I sources observed with GEMINI/GNIRS

Coffey

Bacciotti

Chrysostomou

et al. 2010

A&A

View full text Add to dashboard Cite

Context. In recent years, there has been a number of detections of gradients in the radial velocity profile across jets from young stars. The significance of these results is considerable. They may be interpreted as a signature of jet rotation about its symmetry axis, thereby representing the only existing observational indications supporting the theory that jets extract angular momentum from stardisk systems. However, the possibility that we are indeed observing jet rotation in pre-main sequence systems is undergoing active debate. Aims. To test the validity of a rotation argument, we must extend the survey to a larger sample, including younger sources. Methods. We present the latest results of a radial velocity analysis on jets from Class 0 and I sources, using high resolution data from the infrared spectrograph GNIRS on GEMINI South. We obtained infrared spectra of protostellar jets HH 34, HH 111-H, HH 212 NK1 and SK1. Results. The [Fe II] emission was unresolved in all cases and so Doppler shifts across the jet width could not be accessed. The H 2 emission was resolved in all cases except HH 34. Doppler profiles across the molecular emission were obtained, and gradients in radial velocity of typically 3 km s −1 identified. Conclusions. Agreement with previous studies implies they may be interpreted as jet rotation, leading to toroidal velocity and angular momentum flux estimates of 1.5 km s −1 and 1 × 10 −5 M yr −1 AU km s −1 respectively. However, caution is needed. For example, emission is asymmetric across the jets from HH 212 suggesting a more complex interpretation is warranted. Furthermore, observations for HH 212 and HH 111-H are conducted far from the source implying external influences are more likely to confuse the intrinsic flow kinematics. These observations demonstrate the difficulty of conducting this study from the ground, and highlight the necessity for high angular resolution via adaptive optics or space-based facilities.

show abstract

Rotation of Jets from Young Stars: New Clues from theHubble Space TelescopeImaging Spectrograph

Cited by 185 publications

References 15 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

High-resolution visible spectroscopy of the jet-driving star Th 28

Searching for jet rotation in Class 0/I sources observed with GEMINI/GNIRS

Contact Info

Product

Resources

About