J. Cernicharo. “The interpreation H 2 O Observations” Water Vapour in Astrophysics Models and Observations FROM ISO, SWAS and ODIN TO HERSCHEL José Cernicharo CSIC. IEM Dpt. of Molecular and Infrared Astrophysics (DAMIR) Madrid. Spain 

J. Cernicharo. “The interpreation H 2 O Observations” The problem of the observation of water vapor : Our atmosphere is full of water vapor. Water vapor was detected in the ISM and CSM in 1969 from observations at a 22 GHz (Cheung et al.). Our atmosphere is transparent at this frequency as the transition involves two levels at 700 K and the line strength is rather low. Water detected only in small regions of the ISM and CSM To observe H 2 O we have to go to space !!! But this is not completely true !!!!!!

J. Cernicharo. “The interpreation H 2 O Observations” GROUND : Large amount of data at 22 GHz. Data on some millimeter and submillimeter masering lines. Large amount of data at GHz with the 30-m IRAM telescope. KAO : Search for H 2 18 O Search for H 2 O from high redshift galaxies (Encrenaz and collab.) ISO : OBSERVATION OF A LARGE NUMBER OF PURE ROTATIONAL AND RO-VIBRATIONAL LINES SWAS & ODIN : LARGE SCALE MAPS WITH HIGH SPECTRAL RESOLUTION OF INSTERSTELLAR CLOUDS AT 556 GHz. WHAT IS KNOWN ON WATER VAPOUR IN THE ISM AND CSM ? WHY WE BUILD NEW INSTRUMENTS TO OBSERVE H 2 O

J. Cernicharo. “The interpreation H 2 O Observations”

GROUND OBSERVATIONS OF WATER VAPOUR

J. Cernicharo. “The interpreation H 2 O Observations”

In 1994 we had an exceptional weather. The water vapor amount about the telescope was mm. Several sources were observed (Orion, W49, HH7-11) and more than 40 evolved stars were detected

Orion IRc2

J. Cernicharo. “The interpreation H 2 O Observations”

H 2 O at 325 GHz HPBW = 22” Cernicharo et al. 1999, ApJ Letters The ground based observations of water vapour at 183 and 325 GHz indicated a high abundance for this species, x(H 2 O)=10 -4, in the shocked gas around IRc2, an abun- dance  in the gas surrounding this source (  50”) and >10 -6 over spatial scales  2 arcminutes. There is not way to pump this weak masers if x(H 2 O) is below 10 -6

J. Cernicharo. “The interpreation H 2 O Observations”

Cernicharo et al., 1996, A&A, 305, L5

J. Cernicharo. “The interpreation H 2 O Observations” WATER OBSERVATIONS FROM SPACE

J. Cernicharo. “The interpreation H 2 O Observations” ISO : OBSERVATION OF A LARGE NUMBER OF PURE ROTATIONAL AND RO-VIBRA- TIONAL LINES SWAS : LARGE SCALE MAPS WITH HIGH SPECTRAL RESOLUTION OF INSTERSTE- LLAR CLOUDS. WHAT IS KNOWN ON WATER VAPOUR IN THE ISM AND CSM ?

J. Cernicharo. “The interpreation H 2 O Observations”

The pumping of H 2 O is strongly affected by the dust grains absorption/ emission. Radiative transfer models have to in- clude these effects as they become crucial as soon as the dust opacity is  1. González-Alfonso et. al. 1998, ApJ Letters, 502,L169

J. Cernicharo. “The interpreation H 2 O Observations” González-Alfonso et al., 1999

J. Cernicharo. “The interpreation H 2 O Observations”

The interpretation of the data requires extra information about the spatial distribution of the different physical conditions in the region The SWAS data on the line indicate a larger region of emission at 556 GHz with linewidths of a few km s -1 The IRAM 30-m and CSO data indicate a large region of emission at and 325 GHz (weak masers). These data show that several regions with very different physical conditions have to be conside- red in any realistic model. Large H 2 O abundances are required. Photons emitted in the dense internal regions of the Orion ridge are absorbed and reemitted again in the low density surrounding gas. H 2 O at 556 GHz is much more sensitive to these effects than the 180  m line because its upper energy level will be unpopulated in the low density regions

J. Cernicharo. “The interpreation H 2 O Observations”

Neufeld et al., 2000, ApJ, 539, L111

J. Cernicharo. “The interpreation H 2 O Observations” Modelling water in SgrB2: Absolute need for GHz data Three different codes : J. Cernicharo (non local) A. Asensio (non local) C. Ceccarelli (LVG) Velocity resolution limits the Interpretation : HERSCHEL Cernicharo et al. in preparation

J. Cernicharo. “The interpreation H 2 O Observations” N(H 2 O)= cm -2

J. Cernicharo. “The interpreation H 2 O Observations” N(H 2 O)= cm -2

J. Cernicharo. “The interpreation H 2 O Observations” IRAM 30-m radio telescope observations Herschel will have a similar beam

J. Cernicharo. “The interpreation H 2 O Observations” The ISO data on Orion and SgrB2 indicate that the interpretation of the observations is not obvious at all. Dust emission and absorption produces important effects in the excitation of the ro-vibrational levels of H 2 O. Detailed modelling is required. High spectral resolution is needed to resolve the complex H 2 O line profiles. High spatial angular resolution is needed to resol- ve the different components of the observed absorp- tion/emission ==> HERSCHEL

J. Cernicharo. “The interpreation H 2 O Observations” LOW MASS STAR FORMING REGIONS : EXCITATION THROUGH COLLISIONS LESS IMPORTANT EFFECTS OF THE DUST VERY IMPORTANT EFFECTS IF THE UNCERTAINTIES ON THE COLLISIONAL RATES ARE LARGE ISO HAS PROVIDE A LOT OF DATA ON THIS FIELD (Ceccarelli, Saraceno, Nissini,....)

J. Cernicharo. “The interpreation H 2 O Observations” Young low mass stars : Shocks propagating into the cold surroun- ding gas. How we trace the shocked gas ? In the submillimeter and far-infrared do- main through high-J lines of CO, H 2 O and other molecular species. Cep E Moro et al., 2000, ApJ, submitted

J. Cernicharo. “The interpreation H 2 O Observations” Moro et al., 2000, ApJ, submitted

J. Cernicharo. “The interpreation H 2 O Observations” Water in evolved stars O-rich stars : H 2 O a key molecule C-rich ProtoPlanetary Nebula : H 2 O as a product of photodissociation and shocks C-rich AGB stars : H 2 O from vaporization of cometary bodies ! ?

J. Cernicharo. “The interpreation H 2 O Observations” W Hya Barlow et al., 1996; Neufeld et al., 1996

J. Cernicharo. “The interpreation H 2 O Observations” Asensio, Cernicharo, González-Alfonso in preparation VY CMa All features are real All pure rotational lines of wapour with >43 um detected Some lines from the v 2 =1 bending level also detected Modelling requires collisional rates for Tk= K including ro-vibrational collisions

J. Cernicharo. “The interpreation H 2 O Observations” In O-rich stars water vapour is an excellent tracer of the physical conditions of the circustellar envelope. The systematic observation of as many lines as possible of water could permit to determine the temperature and density profile if (and only if) 1) Collisional rates are well known 2) Good spectral resolution is achieved at all wavelengths (HIFI) 3) CO and other key species are observed and interpreted with the same models than water vapour 4) Good and fast radiative transfer codes are available Systematic surveys of a few selected lines of O-rich stars could per- mit to derive reasonably accurate mass loss rates even for very low dM/dt

J. Cernicharo. “The interpreation H 2 O Observations” DARK CLOUDS

J. Cernicharo. “The interpreation H 2 O Observations” The Galactic Center region offers the possibility to study dark clouds through the absorption of its pure rotational and ro-vibrational lines (background continuum emission is high enough at 6.2 micron and in the far infrared). The different opacity of the pure rotational lines and of the rovibra- tional lines can permit to derive reasonable estimates of the water vapour abundance in dark clouds in front of bright background sources. The pure rotational lines are optically thick even for low water vapour abundances  ( ; 556 GHz) = x(H 2 O) /  v(km s -1 )  ( ; 180  m) = x(H 2 O) /  v(km s -1 ) Much larger abundances are needed to get similar opacities in the mid-infrared (bending mode of water vapour)

J. Cernicharo. “The interpreation H 2 O Observations” ISO/SWS data on Sgr A* (Moneti, Cernicharo & Pardo ApJ Letters,2001)

J. Cernicharo. “The interpreation H 2 O Observations”

Gas Phase (Moneti et al. 2001) x( 13 CO)/x(H 2 O)  5.8 and x(CO)/ x(H 2 O)  350 assuming x(CO)=10 -4 then x(H 2 O)   ( ; 180  m)  100 SWAS in TMC1 provides x(H 2 O) < Ices (Chiar et al SgrA*-) N(CO) = cm -2 N(H 2 O) = cm -2 N ice+gas (CO)/N ice+gas (H 2 O)  5

J. Cernicharo. “The interpreation H 2 O Observations” HERSCHEL will provide a unique opportunity to study the role of water vapour in the chemistry and energy balance of Interstellar and Circumstellar clouds. The high spectral resolution provided by HIFI will permit to get information on the kinematics of the innermost zones of star forming regions and of evolved stars. The full wavelength coverage of HIFI + PACS + SPIRE will permit to determine the physical conditions of regions similar to Orion but much more distant. Objects like Arp220 but at larger refshift could be easily detected. Water vapour is an excellent tracer of shocked regions. The high angular resolution of HERSCHEL and the high spectral resolution of HIFI will permit to study in detail the physical conditions of the gas surrounding low mass star forming regions.

J. Cernicharo. “The interpreation H 2 O Observations” González et al., 2004

J. Cernicharo. “The interpreation H 2 O Observations” GHz water line in low redshift AGNs : a new H 2 O megamaser Cernicharo et al., 2004, in preparation

J. Cernicharo. “The interpreation H 2 O Observations” Important efforts have been made to model H 2 O emission/absorption Calculation of collisional cross sections in progress !!! Interpreting very optically thick lines ! Herschel :: multi-line observations of H 2 O  More realistic physics in the modeling of water vapour Ground based observations : GHz  high angular resolution with ALMA  the possibility to trace H 2 O in protostellar disks !!