The Immediate Environments of Two Herbig Be Stars: MWC 1080 and Hd 259431

Li, Dan; Mariñas, Naibí; Telesco, C. M.

doi:10.1088/0004-637x/796/2/74

Cited by 12 publications

(18 citation statements)

References 35 publications

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“…CO and CS observations revealed a biconical outflow cavity with a size of 0.3 pc × 0.05 pc around MWC 1080, which was most likely created by the bipolar outflow from MWC 1080A (Wang et al 2008). Using narrow-band MIR imaging at 11.2, 11.6, and 18.5 µm, Li et al (2014) showed that the filamentary nebulosity of the MWC 1080 system extends to ∼ 0.15 pc, which traces the internal surfaces of the gas cavity. Strong extended emission at 850 µm as well as SED indicates the existence of a hole in its disk (R ≈ 2 ± 1 AU; Merín et al 2010), and millimeter imaging suggets a slightly large gap (R = 10 +10 −2 AU: van der Marel et al 2016, or ∼ 30 AU: Andrews et al 2011).…”

Section: A53 Mwc 1080mentioning

confidence: 96%

“…Its distance is estimated to vary from ∼ 290 pc (e.g., Juhász et al 2010) to 800 pc (Kraus et al 2008b). Depending on the adopted distance, its stellar luminosity also largely varies (e.g., ≈ 320 L ⊙ : Li et al 2014; 760 +500 −350 L ⊙ : Menu et al 2015;1550L ⊙ : Kraus et al 2008b2233L ⊙ : Alecian et al 2013. Li et al (2014) found similarities between HD 259431 and MWC 1080, suggesting that the extended, filamentary emission at 11.2 and 18.5 µm surrounding HD 259431 may arise from an outflow cavity like MWC 1080.…”

Section: A40 Hd 259431mentioning

confidence: 99%

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Polycyclic Aromatic Hydrocarbons in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars

Seok¹,

Li²

2017

ApJ

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A distinct set of broad emission features at 3. 3, 6.2, 7.7, 8.6, 11.3, and 12.7 µm, is often detected in protoplanetary disks (PPDs). These features are commonly attributed to polycyclic aromatic hydrocarbons (PAHs). We model these emission features in the infrared spectra of 69 PPDs around 14 T Tauri and 55 Herbig Ae/Be stars in terms of astronomical-PAHs. For each PPD, we derive the size distribution and the charge state of PAHs. We then examine the correlations of the PAH properties (i.e., sizes and ionization fractions) with the stellar properties (e.g., stellar effective temperature, luminosity, and mass). We find that the characteristic size of PAHs shows a tendency of correlating with the stellar effective temperature (T eff ) and interpret this as the preferential photodissociation of small PAHs in systems with higher T eff of which the stellar photons are more energetic. In addition, the PAH size shows a moderate correlation with the red-ward wavelength-shift of the 7.7 µm PAH feature that is commonly observed in disks around cool stars. The ionization fraction of PAHs does not seem to correlate with any stellar parameters. This is because the charging of PAHs depends on not only the stellar properties (e.g., T eff , luminosity) but also the spatial distribution of PAHs in the disks. The mere negative correlation between the PAH size and the stellar age suggests that continuous replenishment of PAHs via the outgassing of cometary bodies and/or the collisional grinding of planetesimals and asteroids is required to maintain the abundance of small PAHs against complete destruction by photodissociation.

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Section: A53 Mwc 1080mentioning

confidence: 96%

Section: A40 Hd 259431mentioning

confidence: 99%

Polycyclic Aromatic Hydrocarbons in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars

Seok¹,

Li²

2017

ApJ

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“…1. The 11.2 µm image of MWC 1080 is adopted from Li et al (2014), and the data were taken using Michelle, the facility mid-IR camera at Gemini North.…”

Section: Observation and Data Reductionmentioning

confidence: 99%

Detection of Polarized Infrared Emission by Polycyclic Aromatic Hydrocarbons in the MWC 1080 Nebula

Zhang¹,

Telesco²,

Hoang³

et al. 2017

ApJ

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Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in astrophysical environments, as revealed by their pronounced emission features at 3. 3, 6.2, 7.7, 8.6, 11.3, and 12.7 µm commonly ascribed to the C-H and C-C vibrational modes. Although these features have long been predicted to be polarized, previous searches for PAH polarization led to null or, at best, tentative detections. Here we report the definite detection of polarized PAH emission at 11.3 µm in the nebula associated with the Herbig Be star MWC 1080. We measure a polarization degree of 1.9±0.2%, which is unexpectedly high compared to models. This poses a challenge in the current understanding of the alignment of PAHs, which is required to polarize the PAH emission but thought to be substantially suppressed. PAH alignment with a magnetic field via a resonance paramagnetic relaxation process may account for such a high level of polarization.

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“…Lazareff et al also estimated a disk major-axis PA of 44 • but, with an uncertainty of 42 • , were unable to place strong constraints on this value, a problem that is possibly compounded by the low (close to face-on) disk inclination. The large-scale structures around MWC 147 were studied by Li et al (2014) who utilized deep MIR imaging to observe the surrounding diffuse nebula. In their study, Li et al found that the shape of the nebula is highly asymmetric, with a bow-like structure extending from the central star along a PA of ∼120 • .…”

Section: Introductionmentioning

confidence: 99%

Compact gaseous accretion disk in Keplerian rotation around MWC 147

Hone¹,

Kraus²,

Davies³

et al. 2019

A&A

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Context. The disks around some Herbig Be stars have been observed to be more compact than the expected dust sublimation radius for such objects, with highly refractory dust grains and optically thick gas emission having been proposed as possible explanations for this phenomenon. Aims. Previously, the "undersized" Herbig Be star MWC 147 was observed with interferometry, with the results indicating the presence of a compact gaseous disk based on the measured wavelength-dependence of near-infrared/mid-infrared visibilities. Our aim is to search for direct evidence for the presence of hot gas inside of the expected dust sublimation radius of MWC 147. Methods. By combining VLTI/AMBER spectro-interferometry (R = 12 000) with CRIRES spectroscopy (R = 100 000) we can both spectrally and spatially resolve the Brγ line-emitting gas around MWC 147. Additionally, using CHARA/CLIMB enables us to achieve baseline lengths up to 330m, offering ∼2 times higher angular resolution (and a better position angle coverage) than has previously been achieved with interferometry for MWC 147. To model the continuum we fit our AMBER and CLIMB measurements with a geometric model of an inclined Gaussian distribution as well as a ring model. We fit our high resolution spectra and spectrointerferometric data with a kinematic model of a disk in Keplerian rotation. Results. Our interferometric visibility modelling of MWC 147 indicates the presence of a compact continuum disk with a close to face-on orientation. We model the continuum with an inclined Gaussian, as well as a ring with a radius of 0.60 mas (0.39 au) which is well within the expected dust sublimation radius of 1.52 au. We detect no significant change in the measured visibilities across the Brγ line, indicating that the line-emitting gas is located in the same region as the continuum-emitting disk. Using our differential phase data we construct photocentre displacement vectors across the Brγ line, revealing a velocity profile consistent with a rotating disk. We fit our AMBER spectro-interferometry data with a kinematic model of a disk in Keplerian rotation, with both the line-emitting and continuum-emitting components of the disk originating from the same compact region close to the central star. The presence of line-emitting gas in the same region as the K-band continuum supports the interpretation that the K-band continuum traces an optically-thick gas disk. Conclusions. Our spatially and spectrally resolved observations of MWC 147 reveal that the K-band continuum and Brγ emission both originate from a similar region which is 3.9 times more compact than the expected dust sublimation radius for the star, with Brγ emitted from the accretion disk or disk wind region and exhibiting a rotational velocity profile. We conclude that we detect the presence of a compact, gaseous accretion disk in Keplerian rotation around MWC 147

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The Immediate Environments of Two Herbig Be Stars: MWC 1080 and Hd 259431

Cited by 12 publications

References 35 publications

Polycyclic Aromatic Hydrocarbons in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars

Polycyclic Aromatic Hydrocarbons in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars

Detection of Polarized Infrared Emission by Polycyclic Aromatic Hydrocarbons in the MWC 1080 Nebula

Compact gaseous accretion disk in Keplerian rotation around MWC 147

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