Scientific Result on Massive Star Formation:

[beecee]

https://phys.org/news/2018-11-alma-highest-frequency-scientific-result.html#jCp

ALMA's highest frequency receiver produces its first scientific result on massive star formation:

November 22, 2018, National Astronomical Observatory of Japan:

The Atacama Large Millimeter/submillimeter Array (ALMA) has tuned in another new channel for signals from space. Using its highest frequency receivers yet, researchers obtained 695 radio signatures for various molecules, including simple sugar, in the direction of a massive star forming region. These first scientific results from the ALMA Band 10 receivers developed in Japan ensure a promising future for high frequency observations.

Similar to how different radio stations on Earth broadcast different information, the various frequencies of radio waves coming from space carry different information about the environment and chemical composition at their source. ALMA's Band 10 (787 to 950 GHz) receivers are its highest frequency band yet. It has been a difficult frequency band to observe, not just for ALMA, but for other ground-based radio telescopes as well.

Read more at: https://phys.org/news/2018-11-alma-highest-frequency-scientific-result.html#jCp

the paper:

https://arxiv.org/pdf/1808.05438.pdf

First Results of an ALMA Band 10 Spectral Line Survey of NGC 6334I: Detections of Glycolaldehyde (HC(O)CH2OH) and a New Compact Bipolar Outflow in HDO and CS:

ABSTRACT:

We present the first results of a pilot program to conduct an ALMA Band 10 spectral line survey of the high-mass star-forming region NGC 6334I. The observations were taken in exceptional weather conditions (0.19 mm precipitable water) with typical system temperatures Tsys <950 K at ∼890 GHz. A bright, bipolar north-south outflow is seen in HDO and CS emission, driven by the embedded massive protostar MM1B. This has allowed, for the first time, a direct comparison of the thermal water in this outflow to the location of water maser emission from prior 22 GHz VLA observations. The maser locations are shown to correspond to the sites along the outflow cavity walls where high velocity gas impacts the surrounding material. We also compare our new observations to prior Herschel HIFI spectral line survey data of this field, detecting an order of magnitude more spectral lines (695 vs 65) in the ALMA data. We focus on the strong detections of the complex organic molecule glycolaldehyde (HC(O)CH2OH) in the ALMA data that is not detected in the heavily beam-diluted HIFI spectra. Finally, we stress the need for dedicated THz laboratory spectroscopy to support and exploit future high-frequency molecular line observations with ALMA.

 

4. CONCLUSIONS:

We have presented a first look at ALMA Band 10 spectral line survey toward a line-rich source – the high-mass star-forming region NGC 6334I – obtained in exceptional weather conditions. The resulting map shows a bright, bi-polar north-south outflow from the central massive protostar MM1b as traced by both HDO and CS emission. A comparison to archival Herschel HIFI data of the source shows the power of spatially resolving underlying substructure with a beam size well-matched to the source, resulting in the unambiguous identification of CH(O)CH2OH. A wealth of additional transitions suggest the presence of additional complex molecules that can be identified once high resolution laboratory data are available. The authors thank the anonymous referee for their careful evaluation which improved the quality of this manuscript. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2017.1.00717.S, #2017.1.00661.S, and #2015.A.00022.T. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Support for B.A.M. was provided by NASA through Hubble Fellowship grant #HST-HF2-51396 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. Support for A.M.B. was provided by the NSF through the Grote Reber Fellowship Program administered by Associated Universities, Inc./National Radio Astronomy Observatory and the Virginia Space Grant Consortium. This research made use of NASAs Astrophysics Data System Bibliographic Services, Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013), and APLpy, an open-source plotting package for Python hosted at http://aplpy.github.com.

Edited November 25, 2018 by beecee