Abstract
We are performing a uniform and unbiased imaging survey of the Large Magellanic Cloud (LMC; ∼7° × 7°) using the IRAC (3.6,4.5, 5.8, and 8 μm) and MIPS (24, 70, and 160 μm) instruments on board the Spitzer Space Telescope in the Surveying the Agents of a Galaxy's Evolution (SAGE) survey, these agents being the interstellar medium (ISM) and stars in the LMC. This paper provides an overview of the SAGE Legacy project, including observing strategy, data processing, and initial results. Three key science goals determined the coverage and depth of the survey. The detection of diffuse ISM with column densities > 1.2 × 1021 Hcm-2 permits detailed studies of dust processes in the ISM. SAGE's point-source sensitivity enables a complete census of newly formed stars with masses >3 M ⊙ that will determine the current star formation rate in the LMC. SAGE's detection of evolved stars with mass-loss rates >1 × 10-8 M⊙ yr-1 will quantify the rate at which evolved stars inject mass into the ISM of the LMC. The observing strategy includes two epochs in 2005, separated by 3 months, that both mitigate instrumental artifacts and constrain source variability. The SAGE data are nonproprietary. The data processing includes IRAC and MIPS pipelines and a database for mining the point-source catalogs, which will be released to the community in support of Spitzer proposal cycles 4 and 5. We present initial results on the epoch 1 data for a region near N79 and N83. The MIPS 70 and 160 μm images of the diffuse dust emission of the N79/N83 region reveal a similar distribution to the gas emissions, especially the H I 21 cm emission. The measured point-source sensitivity for the epoch 1 data is consistent with expectations for the survey. The point-source counts are highest for the IRAC 3.6 μm band and decrease dramatically toward longer wavelengths, consistent with the fact that stars dominate the point-source catalogs and the dusty objects detected at the longer wavelengths are rare in comparison. The SAGE epoch 1 point-source catalog has ∼4 × 106 sources, and more are anticipated when the epoch 1 and 2 data are combined. Using Milky Way (MW) templates as a guide, we adopt a simplified point-source classification to identify three candidate groups - stars without dust, dusty evolved stars, and young stellar objects-that offer a starting point for this work. We outline a strategy for identifying foreground MW stars, which may comprise as much as 18% of the source list, and background galaxies, which may comprise ∼12% of the source list.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2268-2288 |
| Number of pages | 21 |
| Journal | Astronomical Journal |
| Volume | 132 |
| Issue number | 6 |
| DOIs | |
| State | Published - Dec 2006 |
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Keywords
- Dust, extinction
- ISM: general
- Magellanic clouds
- Stars: AGB and post-AGB
- Stars: formation
- Stars: mass loss
- Supergiants
- Surveys
ASJC Scopus subject areas
- Space and Planetary Science
- Astronomy and Astrophysics
Cite this
Spitzer survey of the large magellanic cloud : Surveying the agents of a Galaxy's evolution (SAGE). I. Overview and initial results. / Meixner, Margaret; Gordon, Karl D.; Indebetouw, Remy; Hora, Joseph L.; Whitney, Barbara; Blum, Robert; Reach, William; Bernard, Jean Philippe; Meade, Marilyn; Babler, Brian; Engelbracht, Charles W.; For, Bi Qing; Misselt, Karl; Vijh, Uma; Leitherer, Claus; Cohen, Martin; Churchwell, Ed B.; Boulanger, Francois; Frogel, Jay A.; Fukui, Yasuo; Gallagher, Jay; Gorjian, Varoujan; Harris, Jason; Kelly, Douglas; Kawamura, Akiko; Kim, SoYoung; Latter, William B.; Madden, Suzanne; Markwick-Kemper, Ciska; Mizuno, Akira; Mizuno, Norikazu; Mould, Jeremy; Nota, Antonella; Oey, M. S.; Olsen, Knut; Onishi, Toshikazu; Paladini, Roberta; Panagia, Nino; Perez-Gonzalez, Pablo; Shibai, Hirosm; Sato, Shuji; Smith, Linda; Staveley-Smith, Lister; Tielens, A. G G M; Ueta, Toshiya; Van Dyk, Schuyler; Volk, Kevin; Werner, Michael; Zaritsky, Dennis F.
In: Astronomical Journal, Vol. 132, No. 6, 12.2006, p. 2268-2288.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Spitzer survey of the large magellanic cloud
T2 - Surveying the agents of a Galaxy's evolution (SAGE). I. Overview and initial results
AU - Meixner, Margaret
AU - Gordon, Karl D.
AU - Indebetouw, Remy
AU - Hora, Joseph L.
AU - Whitney, Barbara
AU - Blum, Robert
AU - Reach, William
AU - Bernard, Jean Philippe
AU - Meade, Marilyn
AU - Babler, Brian
AU - Engelbracht, Charles W.
AU - For, Bi Qing
AU - Misselt, Karl
AU - Vijh, Uma
AU - Leitherer, Claus
AU - Cohen, Martin
AU - Churchwell, Ed B.
AU - Boulanger, Francois
AU - Frogel, Jay A.
AU - Fukui, Yasuo
AU - Gallagher, Jay
AU - Gorjian, Varoujan
AU - Harris, Jason
AU - Kelly, Douglas
AU - Kawamura, Akiko
AU - Kim, SoYoung
AU - Latter, William B.
AU - Madden, Suzanne
AU - Markwick-Kemper, Ciska
AU - Mizuno, Akira
AU - Mizuno, Norikazu
AU - Mould, Jeremy
AU - Nota, Antonella
AU - Oey, M. S.
AU - Olsen, Knut
AU - Onishi, Toshikazu
AU - Paladini, Roberta
AU - Panagia, Nino
AU - Perez-Gonzalez, Pablo
AU - Shibai, Hirosm
AU - Sato, Shuji
AU - Smith, Linda
AU - Staveley-Smith, Lister
AU - Tielens, A. G G M
AU - Ueta, Toshiya
AU - Van Dyk, Schuyler
AU - Volk, Kevin
AU - Werner, Michael
AU - Zaritsky, Dennis F
PY - 2006/12
Y1 - 2006/12
N2 - We are performing a uniform and unbiased imaging survey of the Large Magellanic Cloud (LMC; ∼7° × 7°) using the IRAC (3.6,4.5, 5.8, and 8 μm) and MIPS (24, 70, and 160 μm) instruments on board the Spitzer Space Telescope in the Surveying the Agents of a Galaxy's Evolution (SAGE) survey, these agents being the interstellar medium (ISM) and stars in the LMC. This paper provides an overview of the SAGE Legacy project, including observing strategy, data processing, and initial results. Three key science goals determined the coverage and depth of the survey. The detection of diffuse ISM with column densities > 1.2 × 1021 Hcm-2 permits detailed studies of dust processes in the ISM. SAGE's point-source sensitivity enables a complete census of newly formed stars with masses >3 M ⊙ that will determine the current star formation rate in the LMC. SAGE's detection of evolved stars with mass-loss rates >1 × 10-8 M⊙ yr-1 will quantify the rate at which evolved stars inject mass into the ISM of the LMC. The observing strategy includes two epochs in 2005, separated by 3 months, that both mitigate instrumental artifacts and constrain source variability. The SAGE data are nonproprietary. The data processing includes IRAC and MIPS pipelines and a database for mining the point-source catalogs, which will be released to the community in support of Spitzer proposal cycles 4 and 5. We present initial results on the epoch 1 data for a region near N79 and N83. The MIPS 70 and 160 μm images of the diffuse dust emission of the N79/N83 region reveal a similar distribution to the gas emissions, especially the H I 21 cm emission. The measured point-source sensitivity for the epoch 1 data is consistent with expectations for the survey. The point-source counts are highest for the IRAC 3.6 μm band and decrease dramatically toward longer wavelengths, consistent with the fact that stars dominate the point-source catalogs and the dusty objects detected at the longer wavelengths are rare in comparison. The SAGE epoch 1 point-source catalog has ∼4 × 106 sources, and more are anticipated when the epoch 1 and 2 data are combined. Using Milky Way (MW) templates as a guide, we adopt a simplified point-source classification to identify three candidate groups - stars without dust, dusty evolved stars, and young stellar objects-that offer a starting point for this work. We outline a strategy for identifying foreground MW stars, which may comprise as much as 18% of the source list, and background galaxies, which may comprise ∼12% of the source list.
AB - We are performing a uniform and unbiased imaging survey of the Large Magellanic Cloud (LMC; ∼7° × 7°) using the IRAC (3.6,4.5, 5.8, and 8 μm) and MIPS (24, 70, and 160 μm) instruments on board the Spitzer Space Telescope in the Surveying the Agents of a Galaxy's Evolution (SAGE) survey, these agents being the interstellar medium (ISM) and stars in the LMC. This paper provides an overview of the SAGE Legacy project, including observing strategy, data processing, and initial results. Three key science goals determined the coverage and depth of the survey. The detection of diffuse ISM with column densities > 1.2 × 1021 Hcm-2 permits detailed studies of dust processes in the ISM. SAGE's point-source sensitivity enables a complete census of newly formed stars with masses >3 M ⊙ that will determine the current star formation rate in the LMC. SAGE's detection of evolved stars with mass-loss rates >1 × 10-8 M⊙ yr-1 will quantify the rate at which evolved stars inject mass into the ISM of the LMC. The observing strategy includes two epochs in 2005, separated by 3 months, that both mitigate instrumental artifacts and constrain source variability. The SAGE data are nonproprietary. The data processing includes IRAC and MIPS pipelines and a database for mining the point-source catalogs, which will be released to the community in support of Spitzer proposal cycles 4 and 5. We present initial results on the epoch 1 data for a region near N79 and N83. The MIPS 70 and 160 μm images of the diffuse dust emission of the N79/N83 region reveal a similar distribution to the gas emissions, especially the H I 21 cm emission. The measured point-source sensitivity for the epoch 1 data is consistent with expectations for the survey. The point-source counts are highest for the IRAC 3.6 μm band and decrease dramatically toward longer wavelengths, consistent with the fact that stars dominate the point-source catalogs and the dusty objects detected at the longer wavelengths are rare in comparison. The SAGE epoch 1 point-source catalog has ∼4 × 106 sources, and more are anticipated when the epoch 1 and 2 data are combined. Using Milky Way (MW) templates as a guide, we adopt a simplified point-source classification to identify three candidate groups - stars without dust, dusty evolved stars, and young stellar objects-that offer a starting point for this work. We outline a strategy for identifying foreground MW stars, which may comprise as much as 18% of the source list, and background galaxies, which may comprise ∼12% of the source list.
KW - Dust, extinction
KW - ISM: general
KW - Magellanic clouds
KW - Stars: AGB and post-AGB
KW - Stars: formation
KW - Stars: mass loss
KW - Supergiants
KW - Surveys
UR - http://www.scopus.com/inward/record.url?scp=33845945133&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33845945133&partnerID=8YFLogxK
U2 - 10.1086/508185
DO - 10.1086/508185
M3 - Article
AN - SCOPUS:33845945133
VL - 132
SP - 2268
EP - 2288
JO - Astronomical Journal
JF - Astronomical Journal
SN - 0004-6256
IS - 6
ER -