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تسجيل مستخدم جديدA ring/disk/outflow system associated with W51 North: a very massive star in the making
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تأليف
Luis A. Zapata
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Sensitive and high angular resolution ($sim$ 0.4arcsec) SO$_2$[22$_{2,20}$ $to$ 22$_{1,21}$] and SiO[5$to$4] line and 1.3 and 7 mm continuum observations made with the Submillimeter Array (SMA) and the Very Large Array (VLA) towards the young massive cluster W51 IRS2 are presented. We report the presence of a large (of about 3000 AU) and massive (40 M$_odot$) dusty circumstellar disk and a hot gas molecular ring around a high-mass protostar or a compact small stellar system associated with W51 North. The simultaneous observations of the silicon monoxide molecule, an outflow gas tracer, further revealed a massive (200 M$_odot$) and collimated ($sim14^circ$) outflow nearly perpendicular to the dusty and molecular structures suggesting thus the presence of a single very massive protostar with a bolometric luminosity of more than 10$^5$ L$_odot$. A molecular hybrid LTE model of a Keplerian and infalling ring with an inner cavity and a central stellar mass of more than 60 M$_odot$ agrees well with the SO$_2$[22$_{2,20}$ $to$ 22$_{1,21}$] line observations. Finally, these results suggest that mechanisms, such as mergers of low- and intermediate- mass stars, might be not necessary for forming very massive stars.
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