Tracing Protostellar Evolution by Observations of Ices

1
Tracing Protostellar Evolution by Observations of
Ices

Adwin Boogert Geoff Blake Michiel Hogerheijde
Caltech/OVRO Caltech/OVRO Univ. of Arizona
2
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 13CO isotope in ices
• Conclusions and future work

3
(No Transcript)
4
Ice processing massive protostars
Solid 13CO2

• Evidence envelope heating
• CO2 crystallization (Boogert et al. 2000
  Gerakines et al. 1999)
• H2O 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)

5
Ice processing massive protostars
Solid 13CO2

• Evidence envelope heating
• CO2 crystallization (Boogert et al. 2000
  Gerakines et al. 1999)
• H2O 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)

6
Ices in low mass YSOs

• Ices abundant toward Elias 29 most luminous (30
  Lsun) low mass (1-2 Msun) protostar in r 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

7
Low mass YSOs where are the ices?
(Boogert, Hogerheijde, Ceccarelli, et al., ApJ
570,708, 2002)

• Line of sight Elias 29 is complex!

8
Low mass YSOs where are the ices?
(Boogert, Hogerheijde, Ceccarelli, et al., ApJ
570,708, 2002)

• Line of sight Elias 29 is complex!
• Face on disk located behind large column (AV20)
  of cool (Tlt 40 K) foreground material which may
  well harbor the unprocessed ices.

9
Low mass YSOs ices in disks!
HCO 3-2 OVRO

• 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 mm 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?

CO Keck/NIRSPEC
10
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)
11
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' H2OCO

(Boogert, Hogerheijde Blake, ApJ 568,761, 2002)
12
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' H2OCO
• 'apolar' CO2CO NEW!

(Boogert, Hogerheijde Blake, ApJ 568,761, 2002)
13
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' H2OCO
• 'apolar' CO2CO NEW!
• 'apolar' pure CO

(Boogert, Hogerheijde Blake, ApJ 568,761, 2002)
14
Ice processing in disk

• Are ices in L1489 IRS disk processed?

15
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 CO2 and H2O containing CO ices
  unchanged
• no evidence CO2 formation by energetic processing
• Larger sample needs to be studied!
• See also poster Pontoppidan et al.

(Boogert, Blake Tielens, ApJ 577n1, in press)
16
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 CO2 and H2O containing CO ices
  unchanged
• no evidence CO2 formation by energetic processing
• Larger sample needs to be studied!
• See also poster Pontoppidan et al.

(Boogert, Blake Tielens, ApJ 577n1, in press)
17
Detection of solid 13COnew clues to nature of
apolar ices

• First detection of solid 13CO
• High spectral resolution required!

NGC 7538 IRS9
(Boogert, Blake Tielens, ApJ 577n1, in press)
18
Detection of solid 13COnew clues to nature of
apolar ices

• First detection of solid 13CO
• High spectral resolution required!
• New insights into nature apolar ices
• 13CO well fitted with pure CO, but 12CO.....

NGC 7538 IRS9
(Boogert, Blake Tielens, ApJ 577n1, in press)
19
Detection of solid 13COnew clues to nature of
apolar ices

• First detection of solid 13CO
• High spectral resolution required!
• New insights into nature apolar ices
• 13CO well fitted with pure CO, but 12CO.....
• ...requires ellipsoidal grains

NGC 7538 IRS9
(Boogert, Blake Tielens, ApJ 577n1, in press)
20
Detection of solid 13COnew clues to nature of
apolar ices

• First detection of solid 13CO
• High spectral resolution required!
• New insights into nature apolar ices
• 13CO well fitted with pure CO, but 12CO.....
• ...requires ellipsoidal grains
• CO and CO2 not mixed
• Finally isotope ratios

NGC 7538 IRS9
(Boogert, Blake Tielens, ApJ 577n1, in press)
21
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.
• 13CO 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.