Deep Imaging Surveys of Star-forming Clouds. IV. The Meek and the Mighty: Outflows from Young Stars in Chamaeleon I

Bally, John; Walawender, Josh; Luhman, K. L.; Fazio, G. G.

doi:10.1086/507523

Cited by 30 publications

(31 citation statements)

References 36 publications

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“…A search in the literature reveals no detections of an outflow associated with Glass Ib. The nearest Herbig-Haro outflow, HH 935, has a separation of 92 north of the Glass I system, but it is moving southward (Bally et al 2006). The 2008 Spitzer IRS spectrum did not show H 2 emission at 12.28 and 17.03 μm, which we would have expected if the fine-structure emission was in an outflow.…”

Section: Outflowmentioning

confidence: 70%

The Curious Case of Glass I: High Ionization and Variability of Different Types

Kruger

Richter

Carr

et al. 2013

ApJ

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Our Spitzer IRS observation of the infrared companion Glass Ib revealed fine-structure emission with high ionization ([Ne iii]/[Ne ii] = 2.1 and [S iv]/[S iii] = 0.6) that indicates that the gas is likely illuminated by hard radiation. While models suggest that extreme-ultraviolet radiation could be present in T Tauri stars, this is the first detection of [S iv] and such a high [Ne iii]/[Ne ii] ratio in a young star. We also find that Glass Ib displays the molecules HCN, CO 2 , and H 2 O in emission. Here we investigate the Glass I binary system and consider possible mechanisms that may have caused the high ionization, whether from an outflow or disk irradiation. We also model the spectral energy distributions of Glass Ia and Ib to test if the system is a young member of the Chameleon I star-forming region, and we consider other possible classifications for the system. We find that Glass Ib is highly variable, showing changes in continuum strength and emission features at optical, near-infrared, and mid-infrared wavelengths. The optical light curve indicates that a central stellar component in Glass Ib became entirely visible for 2.5 years beginning in mid-2002 and possibly displayed periodic variability with repeated, short-period dimming during that time. As the fine-structure emission was not detected in observations before or after our Spitzer IRS observation, we explore whether the variable nature of Glass Ib is related to the gas being highly ionized, possibly due to variable accretion or an X-ray flare.

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Section: Outflowmentioning

confidence: 70%

The Curious Case of Glass I: High Ionization and Variability of Different Types

Kruger

Richter

Carr

et al. 2013

ApJ

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“…Bally et al (2006) suggested that ESO-Hα569 as the possible source for the Herbig Haro object 919. HH 919 is an arcminute-long filament with a PA of ∼60°-75°and is located  22 (0.05 pc) southwest of ESO-Hα569.…”

Section: Hst Jet Outflow Imagesmentioning

confidence: 99%

Hubble Space Telescope Scattered-light Imaging and Modeling of the Edge-on Protoplanetary Disk ESO-Hα 569

Wolff

Perrin

Stapelfeldt

et al. 2017

ApJ

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We present new Hubble Space Telescope (HST) Advanced Camera for Surveys observations and detailed models for a recently discovered edge-on protoplanetary disk around ESO-Hα569 (a low-mass T Tauri star in the Cha I star-forming region). Using radiative transfer models, we probe the distribution of the grains and overall shape of the disk (inclination, scale height, dust mass, flaring exponent, and surface/volume density exponent) by model fitting to multiwavelength (F606W and F814W) HST observations together with a literature-compiled spectral energy distribution. A new tool set was developed for finding optimal fits of MCFOST radiative transfer models using the MCMC code emcee to efficiently explore the high-dimensional parameter space. It is able to selfconsistently and simultaneously fit a wide variety of observables in order to place constraints on the physical properties of a given disk, while also rigorously assessing the uncertainties in those derived properties. We confirm that ESO-Hα569 is an optically thick nearly edge-on protoplanetary disk. The shape of the disk is well-described by a flared disk model with an exponentially tapered outer edge, consistent with models previously advocated on theoretical grounds and supported by millimeter interferometry. The scattered-light images and spectral energy distribution are best fit by an unusually high total disk mass (gas+dust assuming a ratio of 100:1) with a disk-tostar mass ratio of 0.16.

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“…A YSO, Cha-MMS2, is located very close to Cha1-C7 and drives a bipolar outflow (see, e.g., Bally et al 2006;Reipurth et al 1996;Mattila et al 1989). We examined the possibility that the second, higher velocity component that we see in our spectra coincides with the redshifted outflow component.…”

Section: Multiple Velocity Componentsmentioning

confidence: 99%

Star formation in Chamaeleon I and III: a molecular line study of the starless core population

Tsitali

Беллоче

Garrod

et al. 2015

A&A

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Context. The Chamaeleon dark molecular clouds are excellent nearby targets for low-mass star formation studies. Even though they belong to the same cloud complex, Cha I and II are actively forming stars while Cha III shows no sign of ongoing star formation. Aims. We aim to determine the driving factors that have led to the very different levels of star formation activity in Cha I and III and examine the dynamical state and possible evolution of the starless cores within them. Methods. Observations were performed in various molecular transitions with the APEX and Mopra telescopes. We examine the kinematics of the starless cores in the clouds through a virial analysis, a search for contraction motions, and velocity gradients. The chemical differences in the two clouds are explored through their fractional molecular abundances, derived from a non-LTE analysis, and comparison to predictions of chemical models.Results. Five cores are gravitationally bound in Cha I and one in Cha III. The so-called infall signature indicating contraction motions is seen toward 8-17 cores in Cha I and 2-5 cores in Cha III, which leads to a range of 13-28% of the cores in Cha I and 10-25% of the cores in Cha III that are contracting and may become prestellar. There is no significant difference in the turbulence level in the two clouds. Future dynamical interactions between the cores will not be dynamically significant in either Cha I or III, but the subregion Cha I North may experience collisions between cores within ∼0.7 Myr. Turbulence dissipation in the cores of both clouds is seen in the high-density tracers N 2 H + 1-0 and HC 3 N 10-9 which have lower non-thermal velocity dispersions compared to C 17 O 2-1, C 18 O 2-1, and C 34 S 2-1. Evidence of depletion in the Cha I core interiors is seen in the abundance distributions of the latter three molecules. The median fractional abundance of C 18 O is lower in Cha III than Cha I by a factor of ∼2. The median abundances of most molecules (except methanol) in the Cha III cores lie at the lower end of the values found in the Cha I cores. A difference in chemistry is thus seen. Chemical models suitable for the Cha I and III cores are used to constrain the effectiveness of the HC 3 N to N 2 H + abundance ratio as an evolutionary indicator. Both contraction and static chemical models indicate that this ratio is a good evolutionary indicator in the prestellar phase for both gravitationally bound and unbound cores. In the framework of these models, we find that the cores in Cha III and the southern part of Cha I are in a similar evolutionary stage and are less chemically evolved than the central region of Cha I. Conclusions. The measured HC 3 N/N 2 H + abundance ratio and the evidence for contraction motions seen towards the Cha III starless cores suggest that Cha III is younger than Cha I Centre and that some of its cores may form stars in the future if contraction does not cease. The cores in Cha I South may on the other hand be transient structures.

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Deep Imaging Surveys of Star-forming Clouds. IV. The Meek and the Mighty: Outflows from Young Stars in Chamaeleon I

Cited by 30 publications

References 36 publications

The Curious Case of Glass I: High Ionization and Variability of Different Types

The Curious Case of Glass I: High Ionization and Variability of Different Types

Hubble Space Telescope Scattered-light Imaging and Modeling of the Edge-on Protoplanetary Disk ESO-Hα 569

Star formation in Chamaeleon I and III: a molecular line study of the starless core population

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