Herschel HIFI:
the Heterodyn Instrument for the Far-Infrared
PI-Institut: SRON, Groningen
– PI/CoPI-Team:
Frank Helmich(PI), Thijs de Graauw, SRON Groningen
Jürgen Stutzki, KOSMA, Universität zu Köln
Tom Phillips, Caltech, USA
Emmanuel Caux, CNRS, Toulouse
– major partner nations
NL, D, USA, F
in total 25 institutes form 13 nations
HIFI Focal Plane Unit
Herschel HIFI | Jürgen Stutzki for the HIFI team | Universität zu Köln| Pag. 1

The heterodyne principle – mixing light
– We mix the sky signal with an ultra-stable local signal such that the difference
frequencies can be detected
– This difference signal can be electronically amplified and analysed
– The difference signal contains all information of the sky signal
Herschel HIFI | Jürgen Stutzki for the HIFI team | Universität zu Köln| Pag. 2

Herschel HIFI:
Key technologies
– superconducting heterodyne mixers
– at close to quantum-limited operation
– local oscillators, without mechanical tuning elements
– up to frequencies of 2 TeraHz
– compact and low power spectroscopy backends
– complex total setup with 2x7 frontends
7 frequency bands
2 polarizations each
only previous heterodyne instruments in space:
NASA Submm Wave Astronomy Satellite (60 cm telescope;
557 GHz water ground state transition)
and very similar: ODIN (astro & atmospheric)
Herschel HIFI | Jürgen Stutzki for the HIFI team | Universität zu Köln| Pag. 3

Herschel HIFI:
The life-cycle of gas and dust in galaxies
ISM in the Milky Way ISM in Galaxies
• Physical conditions • Physical conditions
• Chemistry • Star formation
• Energetics
• Dynamics
• Isotopic gradients
Star formation
• Physical conditions
• Chemistry
• Energetics
• Dynamics
• Role of Water
Solar System
• Water in Giant
Stellar evolution Planets
• Mass loss • Chemistry Martian
• Composition
atmosphere
Herschel HIFI | Jürgen Stutzki for the HIFI team | Universität zu Köln| Pag. 4

Herschel HIFI:
the need for high spectral resolution
example 1:
line profile
bipolar outflow from young star
line width

• thermal velocity-distribution (0.1-1 km/s)
• turbulent motion (3-10 km/s)
systematic motions

• outflows (10-100 km/s)
• rotation (3-30 km/s)
• etc.
thus: R = λ/Δλ =C/Δv= 3000 – 3x106 needed
example 2:
galaxy rotation
Herschel HIFI | Jürgen Stutzki for the HIFI team | Universität zu Köln| Pag. 5

Herschel HIFI
unique science – SPECTRAL SURVEYS
– HIFI is able to scan the complete frequency range between 480-1250 GHz and 1.4-1.9 THz
Caux et al. – IRAS16293
HIFI – Instrument Level Test
Herschel HIFI | Jürgen Stutzki for the HIFI team | Universität zu Köln| Pag. 6

Herschel HIFI
unique science – SPECTRAL SURVEYS
goals
• To determine physical and chemical
conditions
• To determine tracers for different
processes going on at the same time
• To determine evolution, based on
chemical clocks
• To find new species
• Observations of one typical object
per class, three high-mass star-
forming regions are chosen.
• Analysis execised with gas-cell data
obtained in the laboratory
Herschel HIFI | Jürgen Stutzki for the HIFI team | Universität zu Köln| Pag. 7

HIFI Key Programmes
http://herschel.esac.esa.int/Key_Programmes.shtml
Star-formation
WISH – water is star forming regions
HEXOS – Herschel/hifi observations of EXtrordinary Sources:
the Orion and Sgr B2 regions
HS3F = HIFI Spectral Surveys of Star-Forming regions
ISM
WADI – Warm And Dense ISM
PRISMAS – PRobing InterStellar Molecules with Absorption line
Studies
Extragalactic
HEXGAL – the HIFI EXtraGALactic key project
Stellar Evolution
HIFISTARS – The physical and chemical properties of the
circumstellar environments around evolved stars
HSSO - Herschel Solar System Objects
Water and related chemistry in the Solar System
Herschel HIFI | Jürgen Stutzki for the HIFI team | Universität zu Köln| Pag. 8

Herschel HIFI
left out due to the limited time:
• many other exciting scientific opportunities with HIFI
• very exciting technological advancements,
with spin-off to many other new projects in the field
Looking forward to the continuing discussions today and tomorrow ...
THANK YOU
Jürgen Stutzki
for the HIFI team
stutzki@ph1.uni-koeln.de