Herschel-HIFI News

Submitted by Sylvie Beaulieu, Herschel-HIFI Instrument Support Scientist
(Cassiopeia – Spring 2015)

Herschel Interactive Processing Environment (HIPE)

Although HIPE 12.1 is the current released version, the release of HIPE 13.0 is at our door’s step! Please visit the HIPE Download page regularly for an imminent release by mid-April. In the meantime, you are invited to visit What’s New in HIPE for the latest changes in this coming release. Additional information can be found in HIFI Instrument and Calibration. This page will be updated for HIPE 13.0 once this version is released.

Herschel Science Archive (HSA)

Just a reminder that the Herschel Science Archive has been 100 % public domain since the 29th of October 2013. This represents an excellent opportunity for additional astronomical discoveries for the larger Canadian astronomical community. You are thus invited to browse through the Archive and dig for undiscovered treasures! But wait, there’s more! The Herschel data can be used in combination with e.g. JCMT/SCUBA-2 and ALMA data (see Workshop advert) so you may find additional data to complement your science.

The HSA interface is user friendly which makes it easy to search for your favourite object. A new feature of the HSA
interface allows you to access the ‘User Provided Data Products’ supplied by the Key Programmes. Additionally, once
the Archive products are processed with HCSS 13.0, at least 75 % of the Spectral Scan products will have been expertly flagged by ICC, therefore increasing the quality of the deconvolution.

Conferences, workshops and webinars related to Herschel

Herschel feature stories

In this issue, we present three contributions from our Canadian scientists.

Introducing new MSc student James Cambell (working with Dr. Rene Plume, University of Calgary) who will use HIFI data for his mémoire.

This 2016 master’s thesis will explore Herschel-HIFI observations of C18O (5-4), (7-6), (9-8), (11-10), and (15-14) towards a sample of 14 hot cores. With ancillary ground based measurements of C18O (1-0) and (2-1), obtained with IRAM 30m, as well as C18O (3-2), obtained with JCMT, we can derive the total C18O column density with the contribution of the hot emission well constrained. No emission is detected in the highest observed transition towards most of the hot core sample. Synthetic spectra are fit to the observations via local thermodynamic equilibrium (LTE) modelling implemented in CASSIS as well as non-LTE modelling utilizing the RADEX code. Two physical components are required in order to properly fit the line profiles across multiple transitions, which we model as (1) an extended cool clump and (2) an embedded hot core. Clump sizes are estimated from JCMT C18O (3-2) maps allowing us to accurately model the total column density of the extended component for each source. HIFI 13CO (9-8) maps confirm the assumption that the extent of the hot emission is contained within a beam size. We thus model each hot core with an assumed typical size of 0.1 pc yielding an additional estimate of the total column density endemic to the embedded component.

We are looking forward to reading the results in 2016!

Introducing PhD student Kianoosh Tahani (working with Dr. Rene Plume, University of Calgary)

Herschel Observations of EXtra-Ordinary Sources (HEXOS): Analysis of the 1.2 THz Spectral Survey Towards Orion South

We will present results from a spectral survey toward Orion-S, taken by the HIFI instrument aboard the Herschel Space Telescope, in which we detected 744 spectral lines with S/N > 3sig originating from 50 different molecular and atomic species, as well as a number of unidentified lines. Focusing on the not blended lines, we performed LTE modelling for each of the detected species. This analysis provides us with the physical conditions of Orion-S (column density, temperature, source size, etc.). We could identify the presence of both warm (80 K) and cold (40 K) regions.

This work will be submitted soon. Stay tuned, and contact Kianoosh if you would like to learn more!

And a new contribution by our 2014 J.S. Plaskett medalist:

Dr Andy Pon (Max Planck Institute for Extraterrestrial Physics, Garching) and collaborators P. Caselli, D. Johnstone, M. Kaufman, M. J. Butler, F. Fontani, I. Jiménez-Serra, and J. C. Tan

Mid-J CO shock tracing observations of infrared dark clouds I

Infrared dark clouds (IRDCs) are dense, molecular structures in the interstellar medium that can harbour sites of high-mass star formation. IRDCs contain supersonic turbulence, which is expected to generate shocks that locally heat pockets of gas within the clouds. We present observations of the CO J = 8-7, 9-8, and 10-9 transitions, taken with the Herschel Space Observatory, towards four dense, starless clumps within IRDCs (C1 in G028.37+00.07, F1 and F2 in G034.43+0007, and G2 in G034.77-0.55). We detect the CO J = 8-7 and 9-8 transitions towards three of the clumps (C1, F1, and F2) at intensity levels greater than expected from photodissociation region (PDR) models. The average ratio of the 8-7 to 9-8 lines is also found to be between 1.6 and 2.6 in the three clumps with detections, significantly smaller than expected from PDR models. These low line ratios and large line intensities strongly suggest that the C1, F1, and F2 clumps contain a hot ga gas component could be generated by turbulence dissipating in low velocity shocks.

This work is described in more detail in Pon et al. (astro-ph1503.00719).

The University of Waterloo Herschel-HIFI Support Group is committed to assist you with accessing data through the Herschel Science Archive (HSA) and in using the Herschel Interactive Processing Environment (HIPE) to process your data. Please do not hesitate to contact us. Our webpage HIFI has a dedicated page on Data Processing.

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