Near-IR speckle imaging of massive young stellar objects

Álvarez, Carlos; Hoare, M. G.; Glindemann, Andreas; Richichi, A.

doi:10.1051/0004-6361:20034438

Cited by 40 publications

(60 citation statements)

References 110 publications

(183 reference statements)

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“…However, although there is some low surface brightness emission at large angular distances from the protostar, the image is dominated by a conical, monopolar nebula whose centre of brightness is offset from the location of the protostar. The angular extent of the conical nebula (about 2 arc seconds) is rather larger than the typical size of those observed by Alvarez et al (2004) at our 1 kpc distance.…”

Section: Imagescontrasting

confidence: 54%

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Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer – II. The formation of a 25 solar-mass star

Harries

Douglas

Ali

2017

Monthly Notices of the Royal Astronomical Society

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We present a numerical simulation of the formation of a massive star using MonteCarlo-based radiation hydrodynamics (RHD). The star forms via stochastic disc accretion and produces fast, radiation-driven bipolar cavities. We find that the evolution of the infall rate (considered to be the mass flux across a 1500 au spherical boundary), and the accretion rate onto the protostar, are broadly consistent with observational constraints. After 35 kyr the star has a mass of 25 M and is surrounded by a disc of mass 7 M and 1500 au radius, and we find that the velocity field of the disc is close to Keplerian. Once again these results are consistent with those from recent high-resolution studies of discs around forming massive stars. Synthetic imaging of the RHD model shows good agreement with observations in the near-and far-IR, but may be in conflict with observations that suggests that MYSOs are typically circularly symmetric on the sky at 24.5 µm. Molecular line simulations of a CH 3 CN transition compare well with observations in terms of surface brightness and line width, and indicate that it should be possible to reliably extract the protostellar mass from such observations.

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Section: Imagescontrasting

confidence: 54%

“…The longer wavelength images are dominated by cool, dense dust in the disc around the protostar. Alvarez et al (2004) presented H and K band speckle Figure 6. Synthetic spectral energy distributions plotted logarithmically as λF λ against wavelength in microns.…”

Section: Imagesmentioning

confidence: 99%

Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer – II. The formation of a 25 solar-mass star

Harries

Douglas

Ali

2017

Monthly Notices of the Royal Astronomical Society

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“…The first K-band speckle images, taken with the 3.5 mtelescope on Calar Alto were presented by Alvarez et al (2004) and showed substructure in the vicinity of IRS1; namely, two strong blobs (A, PA ∼ −45…”

Section: Previous Studies Of Ngc 7538mentioning

confidence: 99%

Outflows from the high-mass protostars NGC 7538 IRS1/2 observed with bispectrum speckle interferometry

Kraus¹,

Balega

Elitzur

et al. 2006

A&A

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Context. NGC 7538 IRS1 is a high-mass (30 M ) protostar with a CO outflow, an associated ultracompact H  region, and a linear methanol maser structure, which might trace a Keplerian-rotating circumstellar disk. The directions of the various associated axes are misaligned with each other. Aims. We investigate the near-infrared morphology of the source to clarify the relations among the various axes. Methods. K -band bispectrum speckle interferometry was performed at two 6-meter-class telescopes -the BTA 6 m telescope and the 6.5 m MMT. Complementary IRAC images from the Spitzer Space Telescope Archive were used to relate the structures detected with the outflow at larger scales. Results. High-dynamic range images show fan-shaped outflow structure in which we detect 18 stars and several blobs of diffuse emission. We interpret the misalignment of various outflow axes in the context of a disk precession model, including numerical hydrodynamic simulations of the molecular emission. The precession period is ∼280 years and its half-opening angle is ∼40• . A possible triggering mechanism is non-coplanar tidal interaction of an (undiscovered) close companion with the circumbinary protostellar disk. Our observations resolve the nearby massive protostar NGC 7538 IRS2 as a close binary with separation of 195 mas. We find indications for shock interaction between the outflow activities in IRS1 and IRS2. Finally, we find prominent sites of star formation at the interface between two bubble-like structures in NGC 7538, suggestive of a triggered star formation scenario. Conclusions. Indications of outflow precession have been discovered to date in a number of massive protostars, all with large precession angles (∼20-45• ). This might explain the difference between the outflow widths in low-and high-mass stars and add support to a common collimation mechanism.

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“…The well known highmass protostellar system AFGL 961 is situated well within this region (Cohen 1973;Grasdalen et al 1983;Castelaz et al 1985;Lenzen et al 1984;Hodapp 1994). The third component of the system, designated AFGL 961 II (Li & Smith 2005), was first noticed to be associated with a small nebulosity by Eiroa (1981) and later briefly discussed by Hodapp (1994) was considered a cavity with a partial shell surrounding the central young star (Aspin 1998;Alvarez et al 2004). However, the origin of the intriguing YSO is far from clear.…”

Section: Introductionmentioning

confidence: 99%

The Rosette Eye: The Key Transition Phase in the Birth of a Massive Star

Li¹,

Smith²,

Gredel³

et al. 2008

ApJ

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Massive protostars dramatically influence their surroundings via accretion-induced outflows and intense radiation fields. They evolve rapidly, the disk and infalling envelope being evaporated and dissipated in ∼10 5 yr. Consequently, they are very rare and investigating this important phase of early stellar evolution is extremely difficult. Here we present the discovery of a key transient phase in the emergence of a massive young star, in which ultraviolet radiation from the newborn giant has just punctured through its natal core. The massive young stellar object AFGL 961 II is readily resolved in the near-infrared. Its morphology closely resembles a cat's eye and is here dubbed the "Rosette Eye." Emerging ionized flows blow out an hourglass-shaped nebula, which, along with the existence of strong nearinfrared excess, suggests the existence of an accretion disk in the perpendicular direction. The lobes of the hourglass, however, are capped with arcs of static H 2 emission produced by fluorescence. This study has strong implications for our understanding of how massive stars embark on their formation.

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Near-IR speckle imaging of massive young stellar objects

Cited by 40 publications

References 110 publications

Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer – II. The formation of a 25 solar-mass star

Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer – II. The formation of a 25 solar-mass star

Outflows from the high-mass protostars NGC 7538 IRS1/2 observed with bispectrum speckle interferometry

The Rosette Eye: The Key Transition Phase in the Birth of a Massive Star

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