Evidence for wind and accretion in the 
Herbig Be star HD 100546 from <i>FUSE</i> observations

Deleuil, M.; Étangs, A. Lecavelier des; Bouret, Jean-Claude; Roberge, Aki; Vidal‐Madjar, A.; Martin, Crystal L.; Feldman, P. D.; Ferlet, R.

doi:10.1051/0004-6361:20035598

Cited by 27 publications

(34 citation statements)

References 42 publications

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“…Another possibility is X-ray emission related to an accretion shock, similar to the case of cTTS. Magnetospheric accretion has been invoked to explain the shape of Hα line profiles for some HAeBe stars (Muzerolle et al 2004;Deleuil et al 2004), but, again, the free-fall velocities (∼600 km s −1 ) are inconsistent with the observed high X-ray temperatures.…”

Section: Discussionmentioning

confidence: 99%

On the origin of the X-ray emission from Herbig Ae/Be stars

Stelzer

Micela

Hamaguchi

et al. 2006

A&A

100

107

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Context. Herbig Ae/Be stars are fully radiative and not expected to support dynamo action analogous to their convective lower-mass counterparts, the T Tauri stars. Alternative X-ray production mechanisms, related to stellar winds or star-disk magnetospheres have been proposed, but their X-ray emission has remained a mystery. Aims. A study of Herbig Ae/Be stars' global X-ray properties (such as detection rate, luminosity, temperature, variability), helps to constrain the emission mechanism by comparison to other types of stars, e.g. similar-age but lower-mass T Tauri stars, similar-mass but more evolved main-sequence A-and B-type stars, and with respect to model predictions. Methods. We performed a systematic search for Chandra archival observations of Herbig Ae/Be stars. The superior spatial resolution of this satellite with respect to previous X-ray instrumentation has allowed us to also examine the possible role of late-type companions in generating the observed X-rays. Results. In the total sample of 17 Herbig Ae/Be stars, 8 are resolved from X-ray emitting faint companions or other unrelated X-ray bright objects within 10 . The detection fraction of Herbig Ae/Be stars is 76%, but decreases to 35% if all emission is attributed to further known and unresolved companions. The spectral analysis confirms the high X-ray temperatures (∼20 MK) and large range of fractional X-ray luminosities (log L x /L * ) of this class derived from earlier studies of individual objects. Conclusions. Radiative winds are ruled out as an emission mechanism on the basis of the high temperatures. The X-ray properties of Herbig Ae/Be stars are not vastly different from those of their late-type companion stars (if such are known), nor from other young late-type stars used for comparison. Therefore, either a similar kind of process takes place in both classes of objects, or there must be as yet undiscovered companion stars.

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Section: Discussionmentioning

confidence: 99%

On the origin of the X-ray emission from Herbig Ae/Be stars

Stelzer

Micela

Hamaguchi

et al. 2006

A&A

100

107

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“…1), we analyzed dereddened FUSE observations for wavelengths 911−1200 Å, which had been previously analyzed by Deleuil et al (2004) and IUE observations (Valenti et al 2003) for longer wavelengths (1200−3200 Å). The spectra were dereddened using the extinction of A V = 0.36 (Ardila et al 2007) and the extinction law of Draine (2003) for R V = 3.1.…”

Section: Parameters For the Hd 100546 Modelmentioning

confidence: 99%

The warm gas atmosphere of the HD 100546 disk seen byHerschel

Bruderer

Dishoeck

Doty

et al. 2012

A&A

260

454

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Context. With the Herschel Space Observatory, lines of simple molecules (C + , O, and high-J lines of CO, J up 14) have been observed in the atmosphere of protoplanetary disks. When combined with ground-based data on [C i], all principle forms of carbon can be studied. These data allow us to test model predictions for the main carbon-bearing species and verify the presence of a warm surface layer. The absence of neutral carbon [C i], which is predicted by models to be strong, can then be interpreted together with ionized carbon [C ii] and carbon monoxide. Aims. We study the gas temperature, excitation, and chemical abundance of the simple carbon-bearing species C, C + , and CO, as well as O by the method of chemical-physical modeling. Using the models, we explore the sensitivity of the lines to the entering parameters and constrain the region from which the line radiation emerges. Methods. Numerical models of the radiative transfer in the lines and dust are used together with a chemical network simulation and a calculation of the gas energetics to obtain the gas temperature. We present our new model, which is based on our previous models but includes several improvements that we report in detail, together with the results of benchmark tests. Results. A model of the disk around the Herbig Be star HD 100546 is able to reproduce the CO ladder together with the atomic finestructure lines of [O i] and either [C i] or [C ii]. We find that the high-J lines of CO can only be reproduced by a warm atmosphere with T gas T dust . The low-J lines of CO, observable from the ground, are dominated by the outer disk with a radius of several 100 AU, while the high-J CO observable with Herschel-PACS are dominated from regions within some tens of AU. The spectral profiles of high-J lines of CO are predicted to be broader than those of the low-J lines. We study the effect of several parameters including the size of the disk, the gas mass of the disk, the PAH abundance and distribution, and the amount of carbon in the gas phase. Conclusions. The main conclusions of our work are (i) only a warm atmosphere with T gas T dust can reproduce the CO ladder. (ii) The CO ladder together with [O i] and the upper limit to [C i] can be reproduced by models with a high gas/dust ratio and a low abundance of volatile carbon. These models however produce too small amounts of [C ii]. Models with a low gas/dust ratio and more volatile carbon also reproduce CO and [O i], are in closer agreement with observations of [C ii], but overproduce [C i]. Owing to the uncertain origin of the [C ii] emission, we prefer the high gas/dust ratio models, indicating a low abundance of volatile carbon.

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“…However, this scenario would not work efficiently if significant amounts of gas resided in the gaps (as is the case for the transitional disks of Oph IRS 48, HD 141569 and HD 100546, Bruderer et al 2014;Thi et al 2014;Acke & van den Ancker 2006). For HD 100546, the non-negligible accretion rate derived by Deleuil et al (2004) also argues against outward radial mixing through the gap.…”

Section: Forsterite In Transitional Disksmentioning

confidence: 99%

Location and sizes of forsterite grains in protoplanetary disks

Maaskant

Vries

Min

et al. 2015

A&A

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Context. The spectra of protoplanetary disks contain mid-and far-infrared emission features produced by forsterite dust grains. The spectral features contain information about the forsterite temperature, chemical composition and grain size. Aims. We aim to characterize how the 23 and 69 µm features can be used to constrain the physical locations of forsterite in disks. We check for consistency between two independent forsterite temperature measurements: the I 23 /I 69 feature strength ratio and the shape of the 69 µm band. Methods. We performed radiative transfer modeling to study the effect of disk properties to the forsterite spectral features. Temperature-dependent forsterite opacities were considered in self-consistent models to compute forsterite emission from protoplanetary disks. Results. Modelling grids are presented to study the effects of grain size, disk gaps, radial mixing and optical depth to the forsterite features. Independent temperature estimates derived from the I 23 /I 69 feature strength ratio and the 69 µm band shape are most inconsistent for HD 141569 and Oph IRS 48. A case study of the disk of HD 141569 shows two solutions to fit the forsterite spectrum. A model with T ∼ 40 K, iron-rich (∼0−1% Fe) and 1 µm forsterite grains, and a model with warmer (T ∼ 100 K), iron-free, and larger (10 µm) grains. Conclusions. We find that for disks with low upper limits of the 69 µm feature (most notably in flat, self-shadowed disks), the forsterite must be hot, and thus close to the star. We find no correlation between disk gaps and the presence or absence of forsterite features. We argue that the 69 µm feature of the evolved transitional disks HD 141569 and Oph IRS 48 is most likely a tracer of larger (i.e. 10 µm) forsterite grains.

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Evidence for wind and accretion in the Herbig Be star HD 100546 from FUSE observations

Cited by 27 publications

References 42 publications

On the origin of the X-ray emission from Herbig Ae/Be stars

On the origin of the X-ray emission from Herbig Ae/Be stars

The warm gas atmosphere of the HD 100546 disk seen byHerschel

Location and sizes of forsterite grains in protoplanetary disks

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