malcolm’smemories and oh studycesa/cmw/baudry.pdf · alain baudry univ. de bordeaux, lab the...
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Malcolm’s Memoriesand OH study
Alain BaudryUniv. de Bordeaux, LAB
The scientific heritage of Malcolm WalmsleyFlorence, October 1-2, 2018
Simple memories of my early professional life with Malcolm
• First memories date back to my first coming to Effelsberg around 1978
• Our plan with Malcolm was to constrain physical conditions in the cloudsaround the iconic compact HII region, W3(OH) • We thought 18cm lines were insufficient. Observing higher energy states was the right
approach• OH spectroscopy was accurate + coherent set of Aij and freqs. across energy ladder
• Collision rates not well known
• It was my very first contact with the 100m • Malcolm was helping a lot and he decided I should be the PI of this project• Took us 2 years to gather ‘difficult’ observations at 13.4 and 23.8 GHz
• A&A paper published in 1981 with clear conclusions • OH excitation dominated by IR radiation emitted by dust at 150-200K
• OH clouds just against ionization front … we saw absorption
• Splitting of 13.4 GHz, 4-4 line due to Zeeman effect => 6 mG magnetic field
• Later confirmed by VLBA
• This OH paper was the first of a series made with Malcolm, Tom Wilson
and me together with Stephane Guilloteau -using the 100-m & VLA
• About 8 papers devoted to excited OH … truly an ‘adventure’ at that time
• Much due to or initiated by Malcolm who had a leading role in understanding
OH in the Galaxy
• Later, Malcolm strongly encouraged the work led by Thierry Jacq on
deuterated water HDO
• Malcolm helped in developing a radiative transfer code to interpret our data. …
was successful, very well cited publications
• These works, and others, contributed to the good spirit of cooperation
between the MPIfR and Observatoire de Bordeaux groups
• Culminating in joint research programs with the IRAM 30-m and P. de Bure
• Malcolm’s influence and projects strongly contributed in developing the
science coming out of the IRAM facilities
• Indirectly contributed in developing the IRAM institute as a whole
• The very first works done around 1978-1980 were I believe at the root of a most sincere friendship• Never failed even when we were not working together
• Final anecdote: time where I was building up the European ALMA Back-End and Correlator teams & looking for a good engineer in Italy• I discussed with Malcolm & fully trusted his recommendation … was truly succesful
• Malcolm also helped in producing an attractive A&A paper on the ALMA correlator
These simple facts to give evidenceof Malcolm’s generosity and perspicacity