Adwin Boogert Geoff Blake Michiel Hogerheijde Caltech/OVRO Univ. of Arizona Tracing Protostellar Evolution by Observations of Ices

Topics Introduction: a grain in space The technique: ice processing massive protostars Ices toward low mass protostars Ice location along line of sight CO ices in an edge on disk Processing of CO ices Detection of 13 CO isotope in ices Conclusions and future work

Ice processing massive protostars Evidence envelope heating: CO 2 crystallization (Boogert et al. 2000; Gerakines et al. 1999) H 2 O crystallization (Smith et al. 1989) gas/solid ratio increases (van Dishoeck et al. 1997) Detailed modelling gas phase mm-wave observations (van der Tak et al. 2000) Solid 13 CO 2 :

Ice processing massive protostars Evidence envelope heating: CO 2 crystallization (Boogert et al. 2000; Gerakines et al. 1999) H 2 O crystallization (Smith et al. 1989) gas/solid ratio increases (van Dishoeck et al. 1997) Detailed modelling gas phase mm-wave observations (van der Tak et al. 2000) Solid 13 CO 2 :

Ices in low mass YSOs Ices abundant toward Elias 29: most luminous (30 Lsun) low mass (1-2 Msun) protostar in  Oph cloud Before drawing conclusions on ice processing, one needs to locate ices along line of sight With this goal, Elias 29 was studied in gas phase emission lines

Low mass YSOs: where are the ices? Line of sight Elias 29 is complex! (Boogert, Hogerheijde, Ceccarelli, et al., ApJ 570,708, 2002)

Low mass YSOs: where are the ices? Line of sight Elias 29 is complex! Face on disk located behind large column (A V =20) of cool (T< 40 K) foreground material which may well harbor the unprocessed ices. (Boogert, Hogerheijde, Ceccarelli, et al., ApJ 570,708, 2002)

Low mass YSOs: ices in disks! OVRO spectra low mass protostar L1489 IRS show large 2000 AU radius close to edge-on disk, in almost Keplerian rotation with an infall component (Hogerheijde, ApJ 553, 618, 2001) 4.7  m Keck/NIRSPEC CO spectra confirm edge-on infalling nature of disk and confine temperature and density structure (Boogert et al., ApJ 568,761, 2002). How about the ices? HCO OVRO: CO Keck/NIRSPEC:

Ices in disk L1489 IRS Prominent band of solid CO detected toward L1489, originating in large, flaring disk. CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures: (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

Ices in disk L1489 IRS Prominent band of solid CO detected toward L1489, originating in large, flaring disk. CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures: 'polar' H2O:CO (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

Ices in disk L1489 IRS Prominent band of solid CO detected toward L1489, originating in large, flaring disk. CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures: 'polar' H2O:CO 'apolar' CO2:CO [NEW!] (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

Ices in disk L1489 IRS Prominent band of solid CO detected toward L1489, originating in large, flaring disk. CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures: 'polar' H2O:CO 'apolar' CO2:CO [NEW!] 'apolar' pure CO (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

Ice processing in disk Are ices in L1489 IRS disk processed?

Ice processing in disk Are ices in L1489 IRS disk processed? Empirical answer by comparing CO ice band with established unprocessed line of sight, NGC 7538 : IRS9: apolar CO-rich ices evaporated in L1489 IRS disk abundance CO 2 and H 2 O containing CO ices unchanged no evidence CO 2 formation by energetic processing Larger sample needs to be studied! See also poster Pontoppidan et al. (Boogert, Blake & Tielens, ApJ 577n1, in press)

Ice processing in disk Are ices in L1489 IRS disk processed? Empirical answer by comparing CO ice band with established unprocessed line of sight, NGC 7538 : IRS9: apolar CO-rich ices evaporated in L1489 IRS disk abundance CO 2 and H 2 O containing CO ices unchanged no evidence CO 2 formation by energetic processing Larger sample needs to be studied! See also poster Pontoppidan et al. (Boogert, Blake & Tielens, ApJ 577n1, in press)

Detection of solid 13 CO:new clues to nature of apolar ices First detection of solid 13 CO High spectral resolution required! (Boogert, Blake & Tielens, ApJ 577n1, in press) NGC 7538 : IRS9:

Detection of solid 13 CO:new clues to nature of apolar ices First detection of solid 13 CO High spectral resolution required! New insights into nature apolar ices: 13 CO well fitted with pure CO, but 12 CO..... (Boogert, Blake & Tielens, ApJ 577n1, in press) NGC 7538 : IRS9:

Detection of solid 13 CO:new clues to nature of apolar ices First detection of solid 13 CO High spectral resolution required! New insights into nature apolar ices: 13 CO well fitted with pure CO, but 12 CO requires ellipsoidal grains (Boogert, Blake & Tielens, ApJ 577n1, in press) NGC 7538 : IRS9:

Detection of solid 13 CO:new clues to nature of apolar ices First detection of solid 13 CO High spectral resolution required! New insights into nature apolar ices: 13 CO well fitted with pure CO, but 12 CO requires ellipsoidal grains CO and CO 2 not mixed Finally: isotope ratios (Boogert, Blake & Tielens, ApJ 577n1, in press) NGC 7538 : IRS9:

Conclusions/Future Work Comprehensive picture of ices as tracer of evolution of massive YSOs Infrared observations of ices and (sub-)mm observations of gas need to be combined to determine physical conditions and location of ices Ices detected in disks of low mass YSOs. Warm upper layers of L1489 disk show evaporation of apolar ices. No signs energetic processing found. 13 CO isotope new tracer of ices Promising start, but thorough study of large sample of objects both in gas and solid state needed to answer questions on origin and evolution of solar system ices.