https://phys.org/news/2020-09-pair-massive-baby-stars-swaddled.html Pair of massive baby stars swaddled in salty water vapor by National Astronomical Observatory of Japan Please Register or Log in to view the hidden image! ALMA composite image of a binary massive protostar IRAS 16547-4247. Different colors show the different distributions of dust particles (yellow), methyl cyanide (CH3CN, red), salt (NaCl, green), and hot water vapor (H2O, blue). Bottom insets are the close-up views of each components. Dust and methyl cyanide are distributed widely around the binary, whereas salt and water vapor are concentrated in the disk around each protostar. In the wide-field image, the jets from one of the protostars, seen as several dots in the above image, are shown in light blue. Credit: ALMA (ESO/NAOJ/NRAO), Tanaka et al. Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers spotted a pair of massive baby stars growing in salty cosmic soup. Each star is shrouded by a gaseous disk which includes molecules of sodium chloride, commonly known as table salt, and heated water vapor. Analyzing the radio emissions from the salt and water, the team found that the disks are counter rotating. This is the second detection of salt around massive young stars, promising that salt is an excellent marker to explore the immediate surroundings of giant baby stars. more at link................... the paper: https://iopscience.iop.org/article/10.3847/2041-8213/abadfc Salt, Hot Water, and Silicon Compounds Tracing Massive Twin Disks Abstract We report results of Please Register or Log in to view the hidden image!-resolution observations toward the O-type proto-binary system IRAS 16547–4247 with the Atacama Large Millimeter/submillimeter Array. We present dynamical and chemical structures of the circumbinary disk, circumstellar disks, outflows, and jets, illustrated by multi-wavelength continuum and various molecular lines. In particular, we detect sodium chloride, silicon compounds, and vibrationally excited water lines as probes of the individual protostellar disks at a scale of 100 au. These are complementary to typical hot-core molecules tracing the circumbinary structures on a 1000 au scale. The H2O line tracing inner disks has an upper-state energy of Please Register or Log in to view the hidden image!, indicating a high temperature of the disks. On the other hand, despite the detected transitions of NaCl, SiO, and SiS not necessarily having high upper-state energies, they are enhanced only in the vicinity of the protostars. We posit that these molecules are the products of dust destruction, which only happens in the inner disks. This is the second detection of alkali metal halide in protostellar systems after the case of the disk of Orion Source I, and also one of few massive protostellar disks associated with high-energy transition water and silicon compounds. These new results suggest that these "hot-disk" lines may be common in innermost disks around massive protostars, and have great potential for future research of massive star formation. We also tentatively find that the twin disks are counter-rotating, which might give a hint of the origin of the massive proto-binary system IRAS 16547–4247.
