AKARI observations of ice absorption bands towards edge-on young stellar objects

Y. Aikawa, D. Kamuro, I. Sakon, Y. Itoh, H. Terada, J. A. Noble, K. M. Pontoppidan, H. J. Fraser, M. Tamura, R. Kandori, A. Kawamura, M. Ueno

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Abstract

To investigate the composition and evolution of circumstellar ice around low-mass young stellar objects (YSOs), we observed ice absorption bands in the near infrared (NIR) towards eight YSOs ranging from class 0 to class II, among which seven are associated with edge-on disks. We performed slit-less spectroscopic observations using the grism mode of the InfraRed Camera (IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 mu m to 5 mu m, including the CO2 band and the blue wing of the H2O band, which are inaccessible from the ground. We developed procedures to carefully process the spectra of targets with nebulosity. The spectra were fitted with polynomial baselines to derive the absorption spectra. The molecular absorption bands were then fitted with the laboratory database of ice absorption bands, considering the instrumental line profile and the spectral resolution of the grism dispersion element. Towards the class 0-I sources (L1527, IRC-L1041-2, and IRAS 04302), absorption bands of H2O, CO2, CO, and XCN are clearly detected. Column density ratios of CO2 ice and CO ice relative to H2O ice are 21-28% and 13-46%, respectively. If XCN is OCN-, its column density is as high as 2-6% relative to H2O ice. The HDO ice feature at 4.1 mu m is tentatively detected towards the class 0-I sources and HV Tau. Non-detections of the CH-stretching mode features around 3.5 mu m provide upper limits to the CH3OH abundance of 26% (L1527) and 42% (IRAS 04302) relative to H2O. We tentatively detect OCS ice absorption towards IRC-L1041-2. Towards class 0-I sources, the detected features should mostly originate in the cold envelope, while CO gas and OCN-could originate in the region close to the protostar, where there are warm temperatures and UV radiation. We detect H2O ice band towards ASR41 and 2MASSJ 1628137-243139, which are edge-on class II disks. We also detect H2O ice and CO2 ice towards HV Tau, HK Tau, and UY Aur, and tentatively detect CO gas features towards HK Tau and UY Aur.
LanguageEnglish
Article numberA57
JournalAstronomy and Astrophysics
Volume538
Issue numberFebruary
Early online date1 Feb 2012
DOIs
Publication statusPublished - 2012

Fingerprint

ice
absorption spectra
cameras
Infrared Astronomy Satellite
near infrared
young
ice feature
molecular absorption
absorption spectrum
protostars
spectral resolution
gas
gases
wings
infrared absorption
slits
polynomials
envelopes
infrared spectra
methylidyne

Keywords

  • spitzer spectroscopic survey
  • molecular evolution
  • prestellar cores
  • circumstellare disks
  • t-tauri
  • water ice
  • stars- formation
  • infrared-spectroscopy
  • low-mass stars
  • interstellar ice
  • infrared- ISM
  • circumstellar matter
  • hv-tauri-c
  • akari observations
  • ice absorption bands
  • young stellar objects

Cite this

Aikawa, Y., Kamuro, D., Sakon, I., Itoh, Y., Terada, H., Noble, J. A., ... Ueno, M. (2012). AKARI observations of ice absorption bands towards edge-on young stellar objects. Astronomy and Astrophysics, 538(February), [A57]. https://doi.org/10.1051/0004-6361/201015999
Aikawa, Y. ; Kamuro, D. ; Sakon, I. ; Itoh, Y. ; Terada, H. ; Noble, J. A. ; Pontoppidan, K. M. ; Fraser, H. J. ; Tamura, M. ; Kandori, R. ; Kawamura, A. ; Ueno, M. . / AKARI observations of ice absorption bands towards edge-on young stellar objects. In: Astronomy and Astrophysics. 2012 ; Vol. 538, No. February.
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title = "AKARI observations of ice absorption bands towards edge-on young stellar objects",
abstract = "To investigate the composition and evolution of circumstellar ice around low-mass young stellar objects (YSOs), we observed ice absorption bands in the near infrared (NIR) towards eight YSOs ranging from class 0 to class II, among which seven are associated with edge-on disks. We performed slit-less spectroscopic observations using the grism mode of the InfraRed Camera (IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 mu m to 5 mu m, including the CO2 band and the blue wing of the H2O band, which are inaccessible from the ground. We developed procedures to carefully process the spectra of targets with nebulosity. The spectra were fitted with polynomial baselines to derive the absorption spectra. The molecular absorption bands were then fitted with the laboratory database of ice absorption bands, considering the instrumental line profile and the spectral resolution of the grism dispersion element. Towards the class 0-I sources (L1527, IRC-L1041-2, and IRAS 04302), absorption bands of H2O, CO2, CO, and XCN are clearly detected. Column density ratios of CO2 ice and CO ice relative to H2O ice are 21-28{\%} and 13-46{\%}, respectively. If XCN is OCN-, its column density is as high as 2-6{\%} relative to H2O ice. The HDO ice feature at 4.1 mu m is tentatively detected towards the class 0-I sources and HV Tau. Non-detections of the CH-stretching mode features around 3.5 mu m provide upper limits to the CH3OH abundance of 26{\%} (L1527) and 42{\%} (IRAS 04302) relative to H2O. We tentatively detect OCS ice absorption towards IRC-L1041-2. Towards class 0-I sources, the detected features should mostly originate in the cold envelope, while CO gas and OCN-could originate in the region close to the protostar, where there are warm temperatures and UV radiation. We detect H2O ice band towards ASR41 and 2MASSJ 1628137-243139, which are edge-on class II disks. We also detect H2O ice and CO2 ice towards HV Tau, HK Tau, and UY Aur, and tentatively detect CO gas features towards HK Tau and UY Aur.",
keywords = "spitzer spectroscopic survey, molecular evolution, prestellar cores, circumstellare disks, t-tauri, water ice, stars- formation, infrared-spectroscopy, low-mass stars, interstellar ice, infrared- ISM, circumstellar matter, hv-tauri-c, akari observations, ice absorption bands, young stellar objects",
author = "Y. Aikawa and D. Kamuro and I. Sakon and Y. Itoh and H. Terada and Noble, {J. A.} and Pontoppidan, {K. M.} and Fraser, {H. J.} and M. Tamura and R. Kandori and A. Kawamura and M. Ueno",
year = "2012",
doi = "10.1051/0004-6361/201015999",
language = "English",
volume = "538",
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Aikawa, Y, Kamuro, D, Sakon, I, Itoh, Y, Terada, H, Noble, JA, Pontoppidan, KM, Fraser, HJ, Tamura, M, Kandori, R, Kawamura, A & Ueno, M 2012, 'AKARI observations of ice absorption bands towards edge-on young stellar objects' Astronomy and Astrophysics, vol. 538, no. February, A57. https://doi.org/10.1051/0004-6361/201015999

AKARI observations of ice absorption bands towards edge-on young stellar objects. / Aikawa, Y.; Kamuro, D.; Sakon, I.; Itoh, Y.; Terada, H.; Noble, J. A.; Pontoppidan, K. M.; Fraser, H. J.; Tamura, M.; Kandori, R.; Kawamura, A. ; Ueno, M. .

In: Astronomy and Astrophysics, Vol. 538, No. February, A57, 2012.

Research output: Contribution to journalArticle

TY - JOUR

T1 - AKARI observations of ice absorption bands towards edge-on young stellar objects

AU - Aikawa, Y.

AU - Kamuro, D.

AU - Sakon, I.

AU - Itoh, Y.

AU - Terada, H.

AU - Noble, J. A.

AU - Pontoppidan, K. M.

AU - Fraser, H. J.

AU - Tamura, M.

AU - Kandori, R.

AU - Kawamura, A.

AU - Ueno, M.

PY - 2012

Y1 - 2012

N2 - To investigate the composition and evolution of circumstellar ice around low-mass young stellar objects (YSOs), we observed ice absorption bands in the near infrared (NIR) towards eight YSOs ranging from class 0 to class II, among which seven are associated with edge-on disks. We performed slit-less spectroscopic observations using the grism mode of the InfraRed Camera (IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 mu m to 5 mu m, including the CO2 band and the blue wing of the H2O band, which are inaccessible from the ground. We developed procedures to carefully process the spectra of targets with nebulosity. The spectra were fitted with polynomial baselines to derive the absorption spectra. The molecular absorption bands were then fitted with the laboratory database of ice absorption bands, considering the instrumental line profile and the spectral resolution of the grism dispersion element. Towards the class 0-I sources (L1527, IRC-L1041-2, and IRAS 04302), absorption bands of H2O, CO2, CO, and XCN are clearly detected. Column density ratios of CO2 ice and CO ice relative to H2O ice are 21-28% and 13-46%, respectively. If XCN is OCN-, its column density is as high as 2-6% relative to H2O ice. The HDO ice feature at 4.1 mu m is tentatively detected towards the class 0-I sources and HV Tau. Non-detections of the CH-stretching mode features around 3.5 mu m provide upper limits to the CH3OH abundance of 26% (L1527) and 42% (IRAS 04302) relative to H2O. We tentatively detect OCS ice absorption towards IRC-L1041-2. Towards class 0-I sources, the detected features should mostly originate in the cold envelope, while CO gas and OCN-could originate in the region close to the protostar, where there are warm temperatures and UV radiation. We detect H2O ice band towards ASR41 and 2MASSJ 1628137-243139, which are edge-on class II disks. We also detect H2O ice and CO2 ice towards HV Tau, HK Tau, and UY Aur, and tentatively detect CO gas features towards HK Tau and UY Aur.

AB - To investigate the composition and evolution of circumstellar ice around low-mass young stellar objects (YSOs), we observed ice absorption bands in the near infrared (NIR) towards eight YSOs ranging from class 0 to class II, among which seven are associated with edge-on disks. We performed slit-less spectroscopic observations using the grism mode of the InfraRed Camera (IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 mu m to 5 mu m, including the CO2 band and the blue wing of the H2O band, which are inaccessible from the ground. We developed procedures to carefully process the spectra of targets with nebulosity. The spectra were fitted with polynomial baselines to derive the absorption spectra. The molecular absorption bands were then fitted with the laboratory database of ice absorption bands, considering the instrumental line profile and the spectral resolution of the grism dispersion element. Towards the class 0-I sources (L1527, IRC-L1041-2, and IRAS 04302), absorption bands of H2O, CO2, CO, and XCN are clearly detected. Column density ratios of CO2 ice and CO ice relative to H2O ice are 21-28% and 13-46%, respectively. If XCN is OCN-, its column density is as high as 2-6% relative to H2O ice. The HDO ice feature at 4.1 mu m is tentatively detected towards the class 0-I sources and HV Tau. Non-detections of the CH-stretching mode features around 3.5 mu m provide upper limits to the CH3OH abundance of 26% (L1527) and 42% (IRAS 04302) relative to H2O. We tentatively detect OCS ice absorption towards IRC-L1041-2. Towards class 0-I sources, the detected features should mostly originate in the cold envelope, while CO gas and OCN-could originate in the region close to the protostar, where there are warm temperatures and UV radiation. We detect H2O ice band towards ASR41 and 2MASSJ 1628137-243139, which are edge-on class II disks. We also detect H2O ice and CO2 ice towards HV Tau, HK Tau, and UY Aur, and tentatively detect CO gas features towards HK Tau and UY Aur.

KW - spitzer spectroscopic survey

KW - molecular evolution

KW - prestellar cores

KW - circumstellare disks

KW - t-tauri

KW - water ice

KW - stars- formation

KW - infrared-spectroscopy

KW - low-mass stars

KW - interstellar ice

KW - infrared- ISM

KW - circumstellar matter

KW - hv-tauri-c

KW - akari observations

KW - ice absorption bands

KW - young stellar objects

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DO - 10.1051/0004-6361/201015999

M3 - Article

VL - 538

JO - Astronomy and Astrophysics

T2 - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

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