On the massive young stellar object AFGL 4176

Boley, Paul A.; Linz, H.; Boekel, R. van; Bouwman, J.; Henning, Thomas; Соболев, А. М.

doi:10.1051/0004-6361/201218905

Cited by 11 publications

(25 citation statements)

References 44 publications

(57 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The position angle and elongation derived from the 2D1D model here are consistent with the more complicated temperature-gradient disk model presented by Boley et al (2012). The correlated flux (Fig.…”

Section: Afgl 4176supporting

confidence: 87%

“…Besides the observations conducted within the framework of the present survey, we also include the following data previously published by other investigators: one uv point for AFGL 2136 (de Wit et al 2011), and 6 points for R CrA (Correia et al 2008). Finally, we note that observations of select sources, obtained within the context of the survey presented here, have already been published by Linz et al (2009), Follert et al (2010, Grellmann et al (2011), Boley et al (2012.…”

Section: Long-baseline Interferometry With Vltimentioning

confidence: 76%

“…A.2) the fits at short baselines are quite good, but become progressively worse at long baselines. At the longest spatial scales, the imprint of the spatial structure on the correlated flux levels becomes apparent (Boley et al 2012), meaning that the assumption of the underlying emission having a power-law spectrum is incorrect. Such spatial effects may also be present in G305.20+0.21 (Fig.…”

Section: Absorption Spectra and Dust Compositionmentioning

confidence: 99%

See 2 more Smart Citations

The VLTI/MIDI survey of massive young stellar objects

Boley

Linz

Boekel

et al. 2013

A&A

View full text Add to dashboard Cite

Context. Because of inherent difficulties involved in observations and numerical simulations of the formation of massive stars, an understanding of the early evolutionary phases of these objects remains elusive. In particular, observationally probing circumstellar material at distances < ∼ 100 AU from the central star is exceedingly difficult, as such objects are rare (and thus, on average, far away) and typically deeply embedded. Long-baseline mid-infrared interferometry provides one way of obtaining the necessary spatial resolution at appropriate wavelengths for studying this class of objects; however, interpreting such observations is often difficult due to sparse spatial-frequency coverage. Aims. We aim to characterize the distribution and composition of circumstellar material around young massive stars and to investigate exactly which physical structures in these objects are probed by long-baseline mid-infrared interferometric observations. Methods. We used the two-telescope interferometric instrument MIDI of the Very Large Telescope Interferometer of the European Southern Observatory to observe a sample of 24 intermediate-and high-mass young stellar objects in the N band (8-13 μm). We had successful fringe detections for 20 objects and present spectrally-resolved correlated fluxes and visibility levels for projected baselines of up to 128 m. We fit the visibilities with geometric models to derive the sizes of the emitting regions, as well as the orientation and elongation of the circumstellar material. Fourteen objects in the sample show the 10 μm silicate feature in absorption in the total and correlated flux spectra. For 13 of these objects, we were able to fit the correlated flux spectra with a simple absorption model, allowing us to constrain the composition and absorptive properties of the circumstellar material. Results. Nearly all of the massive young stellar objects observed show significant deviations from spherical symmetry at mid-infrared wavelengths. In general, the mid-infrared emission can trace both disks and outflows, and in many cases it may be difficult to disentangle these components on the basis of interferometric data alone, because of the sparse spatial frequency coverage normally provided by current long-baseline interferometers. For the majority of the objects in this sample, the absorption occurs on spatial scales larger than those probed by MIDI. Finally, the physical extent of the mid-infrared emission around these sources is correlated with the total luminosity, albeit with significant scatter. Conclusions. Circumstellar material is ubiquitous at distances < ∼ 100 AU around young massive stars. Long-baseline mid-infrared interferometry provides the resolving power necessary for observing this material directly. However, in particular for deeply-embedded sources, caution must be used when attempting to attribute mid-infrared emission to specific physical structures, such as a circumstellar disk or an outflow.

show abstract

Section: Afgl 4176supporting

confidence: 87%

Section: Long-baseline Interferometry With Vltimentioning

confidence: 76%

Section: Absorption Spectra and Dust Compositionmentioning

confidence: 99%

See 1 more Smart Citation

The VLTI/MIDI survey of massive young stellar objects

Boley

Linz

Boekel

et al. 2013

A&A

View full text Add to dashboard Cite

show abstract

“…Almost all the observed massive stars of their sample presented elongated structures at scales ≤100 AU, which could be associated with disks and/or outflows. Additional MIR interferometry case studies on individual objects include: M8E-IR (Linz et al 2009), M17 SW IRS1 (Follert et al 2010), AFGL 4176 (Boley et al 2012), CRL 2136(de Wit et al 2011, and NGC 2264 IRS 1* (Grellmann et al 2011). We also note that the work of de Wit et al (2007) was one of the first attempts to perform simultaneous model-fitting to the spectral energy distribution (SED) and mid-infrared (MIR) interferometric visibilities of W33A.…”

Section: Introductionmentioning

confidence: 96%

Unveiling the near-infrared structure of the massive-young stellar object NGC 3603 IRS 9A* with sparse aperture masking and spectroastrometry

Sánchez-Bermúdez

Hummel

Tuthill

et al. 2016

A&A

View full text Add to dashboard Cite

Context. Contemporary theory holds that massive stars gather mass during their initial phases via accreting disk-like structures. However, conclusive evidence for disks has remained elusive for most massive young objects. This is mainly due to significant observational challenges: objects are rare and located at great distances within dusty, highly opaque environments. Incisive studies, even targeting individual objects, are therefore relevant to the progression of the field. NGC 3603 IRS 9A* is a young massive stellar object that is still surrounded by an envelope of molecular gas for which previous mid-infrared observations with long-baseline interferometry have provided evidence of a plausible disk of 50 mas diameter at its core. Aims. This work aims at a comprehensive study of the physics and morphology of IRS 9A at near-infrared wavelengths. Methods. New sparse aperture-masking interferometry data, taken with the near-infrared camera NACO of the Very Large Telescope (VLT) at K s and L wavelengths, were analyzed together with archival high-resolution H 2 and Brγ lines obtained with the cryogenic high-resolution infrared schelle spectrograph (CRIRES). Results. The trends in the calibrated visibilities at K s and L -bands suggest the presence of a partially resolved compact object with an angular size of ≤30 mas at the core of IRS 9A, together with the presence of over-resolved flux. The spectroastrometric signal of the H 2 line, obtained from the CRIRES spectra, shows that this spectral feature proceeds from the large-scale extended emission (∼300 mas), while the Brγ line appears to be formed at the core of the object (∼20 mas). To better understand the physics that drive IRS 9A, we have performed continuum radiative transfer modeling. Our best model supports the existence of a compact disk with an angular diameter of 20 mas, together with an outer envelope of 1 exhibiting a polar cavity with an opening angle of ∼30 • . This model reproduces the MIR morphology that has previously been derived in the literature and also matches the spectral energy distribution (SED) of the source. Conclusions. Our observations and modeling of IRS 9A support the presence of a disk at the core, surrounded by an envelope. This scenario is consistent with the brightness distribution (SED) of the source for near-and mid-infrared wavelengths at various spatial scales. However, our model suffers from remaining inconsistencies between SED modelling and the interferometric data. Moreover, the Brγ spectroastrometric signal indicates that the core of IRS 9A exhibits some form of complexity such as asymmetries in the disk. Future high-resolution observations are required to confirm the disk/envelope model and to flesh out the details of the physical form of the inner regions of IRS 9A.

show abstract

“…We would like to correct an error in the position angle reported by Boley et al (2012) for the disk model of the massive young stellar object AFGL 4176. The error arose due to a problem with the angle conventions used, and had no influence on the modeling of the data.…”

mentioning

confidence: 99%