Resolving the MYSO binaries PDS 27 and PDS 37 with VLTI/PIONIER

Koumpia, E.; Ababakr, K. M.; Wit, W. J. de; Oudmaijer, R. D.; Garatti, A. Caratti o; Boley, Paul A.; Linz, H.; Kraus, Stefan; Bouquin, J.-B. Le

doi:10.1051/0004-6361/201834624

Cited by 10 publications

(12 citation statements)

References 53 publications

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“…The presence of a large disc surrounding the fainter object may hint to a more massive but embedded nature of the companion. Both the reported separation and the PA are consistent with Koumpia et al (2019), making the binary nature of G282 a favorable geometry over that of an elongated disc.…”

Section: Finding Binaries -Methodssupporting

confidence: 63%

“…G282.2988 (known also as PDS 37), is the only object for which both an elongated disc or the addition of an off-centred source improved the fit significantly (Figure 6), by reducing the χ 2 from 12 to 2-3. The source was recently identified as binary at shorter H-band wavelengths using PIONIER/VLTI (PDS37; Koumpia et al 2019). The K-band modelling reveals a companion at 23.7±0.1 mas with a primary to secondary flux ratio of 10.4±1.2 and a position angle PA of 260±2 • .…”

Section: Finding Binaries -Methodsmentioning

confidence: 99%

“…Therefore, this limitation should be considered for the two sources of our sample observed with AMBER. G231.7986 (PDS 27) in particular, which is found to be a single brightness distribution based on AMBER observations, was found to show strong binary interferometric signatures on PIONIER H-band observations (Koumpia et al 2019). PDS 27 is the only source in our sample presented in Gravity Collaboration et al (2019).…”

Section: Binary Fractionmentioning

confidence: 96%

“…Direct detections of high-mass binaries covering tighter separations (< 500 au) were obtained serendipitously. In particular, only a handful of such protobinary systems are known, with ranging separations of several hundreds of au (PDS 27: 30 au, PDS 37: 48 au, V921 Sco: 45 au, NGC 7538 IRS1: 430 au, IRAS 17216-3801: 170 au, IRAS 07299-1651: 180 au; Koumpia et al 2019;Kraus et al 2012;Beuther et al 2017;Kraus et al 2017;Zhang et al 2019).…”

Section: Introductionmentioning

confidence: 99%

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The first interferometric survey of massive YSOs in the K-band

Koumpia

Wit

Oudmaijer

et al. 2021

A&A

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Context. Circumstellar discs are essential for the formation of high mass stars, while multiplicity, and in particular binarity, appears to be an inevitable outcome, as the vast majority of massive stars (>8 M⊙) are found in binaries (up to 100%). Our understanding of the innermost regions of accretion discs around massive stars and the binarity of high-mass young stars is sparse because of the high spatial resolution and sensitivity required to trace these rare and distant objects. Aims. We aim to spatially resolve and constrain the sizes of the dust and ionised gas emission from the innermost regions of a sample of massive young stellar objects (MYSOs) for the first time, and to provide high-mass binary statistics for young stars at 2–300 au scales using direct interferometric measurements. Methods. We observed six MYSOs using long-baseline near-infrared K-band interferometry on the VLTI (GRAVITY, AMBER) in order to resolve and characterise the 2.2 μm hot dust emission originating from the inner rim of circumstellar discs around MYSOs, and the associated Brγ emission from ionised gas. We fitted simple geometrical models to the interferometric observables, and determined the inner radius of the dust emission. We placed MYSOs with K-band measurements in a size–luminosity diagram for the first time, and compared our findings to their low- and intermediate-mass counterparts (T Tauris and Herbig AeBes). We also compared the observed K-band sizes (i.e. inner rim radius) to the sublimation radius predicted by three different disc scenarios: a classical thick flattened structure with oblique heating in action, and direct heating from the protostar via an optically thin cavity with and without backwarming effects. Lastly, we applied binary geometries to trace close binarity among MYSOs. Results. The characteristic size of the 2.2 μm continuum emission towards this sample of MYSOs shows a large scatter at the given luminosity range. When the inner sizes of MYSOs are compared to those of lower mass Herbig AeBe and T Tauri stars, they appear to follow a universal trend in that the sizes scale with the square-root of the stellar luminosity. The Brγ emission originates from a similar or somewhat smaller and co-planar area compared to the 2.2 μm continuum emission. We discuss this new finding with respect to a disc-wind or jet origin. Finally, we report an MYSO binary fraction of 17–25% at milli-arcsecond separations (2–300 au). Conclusions. The size–luminosity diagram indicates that the inner regions of discs around young stars scale with luminosity independently of the stellar mass. The observed fraction of MYSO binaries in K-band is almost ‘flat’ for a wide range of separations (2–10 000 au). At the targeted scales (2–300 au), the MYSO binary fraction is lower than what was previously reported for the more evolved main sequence massive stars, which, if further confirmed, could implicate predictions from massive binary formation theories. Lastly, with this study, we can finally spatially resolve the crucial star–disc interface in a sample of MYSOs, showing that au-scale discs are prominent in high-mass star formation and are similar to their low-mass equivalents, while the ionised gas can be linked to disc wind and disc accretion models similar to Herbig AeBes.

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Section: Finding Binaries -Methodssupporting

confidence: 63%

Section: Finding Binaries -Methodsmentioning

confidence: 99%

Section: Binary Fractionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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The first interferometric survey of massive YSOs in the K-band

Koumpia

Wit

Oudmaijer

et al. 2021

A&A

Self Cite

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“…These effects will be more prominent for high-mass stars, which are more likely to form in binary systems (e.g. Sana et al 2014;Kraus et al 2017;Koumpia et al 2019;Zhang et al 2019a).…”

Section: Introductionmentioning

confidence: 99%

A Detailed View of the Circumstellar Environment and Disk of the Forming O-star AFGL 4176

Johnston

Hoare

Beuther

et al. 2020

ApJ

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We present a detailed analysis of the disk and circumstellar environment of the forming O-type star AFGL 4176 mm1, placing results from the Atacama Large Millimeter/submillimeter Array (ALMA) into context with multiwavelength data. With ALMA, we detect seventeen 1.2 mm continuum sources within 5 ′′ (21,000 au) of AFGL 4176 mm1. We find that mm1 has a spectral index of 3.4±0.2 across the ALMA band, with >87% of its 1.2 mm continuum emission from dust. The source mm2, projected 4200 au from mm1, may be a companion or a blueshifted knot in a jet. We also explore the morphological differences between the molecular lines detected with ALMA, finding 203 lines from 25 molecules, which we categorize into several morphological types. Our results show that AFGL 4176 mm1 provides an example of a forming O-star with a large and chemically complex disk, which is mainly traced by nitrogen-bearing molecules. Lines that show strong emission on the blueshifted side of the disk are predominantly oxygen-bearing, which we suggest are tracing a disk accretion shock. The molecules C 34 S, H 2 CS and CH 3 CCN trace a slow wide-angle wind or dense structures in the outflow cavity walls. With the Australia Telescope Compact Array (ATCA), we detect a compact continuum source (<2000 × 760 au) at 1.2 cm, associated with mm1, of which >96% is from ionized gas. The ATCA NH 3 (1,1) and (2,2) emission traces a large-scale (r∼0.5 pc) rotating toroid with the disk source mm1 in the blueshifted part of this structure offset to the northwest.

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