MWC 297: A Young High-mass Star Rotating at Critical Velocity
First Author:
Bram Acke
Email: bram AT ster.kuleuven.be
KULeuven, B
Celestijnenlaan 200D
B-3001, Leuven, Belgium
Coauthors:
Verhoelst, Tijl, KULeuven, B + JBCA, UK
van den Ancker, Mario, ESO, G
Deroo, Pieter, KULeuven, B
Waelkens, Christoffel, KULeuven, B
Chesneau, Olivier, OCA, F
Tatulli, Eric, OAA, I
Benisty, Myriam, LAOG, F
Puga, Elena, KULeuven, B
Waters, Rens, UvA, NL + KULeuven, B
Verhoeff, Arjan, UvA, NL
de Koter, Alex, UvA, NL
Abstract
MWC 297 is a nearby high-mass young star of spectral type B1.5V. The central star is attenuated by 8 mag in the optical and has a high projected rotational velocity of 350 km/s. We argue that the attenuation towards the system is interstellar and most likely due to remnants of the parental cloud. We have probed the circumstellar matter of MWC 297 with spectrally resolved interferometric measurements in the near- (1.6-2.5 micron) and mid-infrared (8-13 micron). The data have allowed us to construct a color image of the flat circumstellar disk. We find that most of the emission at these wavelengths - including the 10 micron silicate emission - emanates from a very compact region around the star (<1.5 AU), well within the dust destruction radius. Moreover, the almost pole-on view on the system (i < 40 deg) implies that the high projected rotational velocity corresponds to an actual velocity which exceeds the critical velocity of the star. Our discovery shows that stars can achieve critical rotation at birth. We discuss the impact of this result in terms of high-mass star formation and main-sequence evolution of classical Be stars.
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