Star formation rates from young-star counts and the structure of the ISM across the NGC 346/N66 complex in the SMC

被引：44

作者：

Hony, S. ^{[1
]}

Gouliermis, D. A. ^{[1
,2
]}

Galliano, F. ^{[3
]}

Galametz, M. ^{[4
]}

Cormier, D. ^{[1
]}

Chen, C. -H. R. ^{[5
]}

Dib, S. ^{[6
,7
]}

Hughes, A. ^{[2
,8
,9
]}

Klessen, R. S. ^{[1
,10
,11
]}

Roman-Duval, J. ^{[12
]}

Smith, L. ^{[12
,13
]}

Bernard, J. -P. ^{[8
,9
]}

Bot, C. ^{[14
]}

Carlson, L. ^{[15
]}

Gordon, K. ^{[12
,16
]}

Indebetouw, R. ^{[15
,17
]}

Lebouteiller, V. ^{[3
]}

Lee, M. -Y. ^{[3
]}

Madden, S. C. ^{[3
]}

Meixner, M. ^{[12
,18
]}

Oliveira, J. ^{[19
]}

Rubio, M. ^{[20
]}

Sauvage, M. ^{[3
]}

Wu, R. ^{[21
]}

机构：

[1] Heidelberg Univ, Inst Theoret Astrophys, Zentrum Astron, D-69120 Heidelberg, Germany

[2] Max Planck Inst Astron, D-69117 Heidelberg, Germany

[3] Univ Paris Diderot, Lab AIM, CEA, IRFU,Serv Astrophys, F-91191 Gif Sur Yvette, France

[4] European So Observ, D-85748 Garching, Germany

[5] Max Planck Inst Radioastron, D-53121 Bonn, Germany

[6] Niels Bohr Inst, Niels Bohr Int Acad, DK-2100 Copenhagen, Denmark

[7] Univ Copenhagen, Ctr Star & Planet Format, DK-1350 Copenhagen, Denmark

[8] IRAP, CNRS, F-31028 Toulouse 4, France

[9] Univ Toulouse, UPS OMP, IRAP, F-31028 Toulouse 4, France

[10] Univ Calif Santa Cruz, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA

[11] Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

[12] Space Telescope Sci Inst, Baltimore, MD 21218 USA

[13] European Space Agcy, Baltimore, MD 21218 USA

[14] Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, F-67000 Strasbourg, France

[15] Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA

[16] Univ Ghent, Sterrenkundig Observ, B-9000 Ghent, Belgium

[17] Natl Radio Astron Observ, Charlottesville, VA 22904 USA

[18] Johns Hopkins Univ, Dept Phys & Astron, Bloomberg Ctr 366, Baltimore, MD 21218 USA

[19] Keele Univ, Sch Phys & Geog Sci, Lennard Jones Labs, Keele ST5 5BG, Staffs, England

[20] Univ Chile, Dept Astron, Santiago, Chile

[21] Univ Tokyo, Grad Sch Sci, Dept Astron, Bunkyo Ku, Tokyo 1130033, Japan

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2015年 / 448卷 / 02期

基金：

美国国家科学基金会; 欧洲研究理事会;

关键词：

stars: pre-main-sequence; ISM: individual objects: NGC 346; ISM: structure; Magellanic Clouds; SMALL-MAGELLANIC-CLOUD; FORMING REGION NGC-346; KENNICUTT-SCHMIDT LAW; GALAXY EVOLUTION; MOLECULAR CLOUDS; STELLAR OBJECTS; LOW METALLICITY; MASSIVE STARS; N; 66; SUBMILLIMETER EXCESS;

D O I：

10.1093/mnras/stv107

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

The rate at which interstellar gas is converted into stars, and its dependence on environment, is one of the pillars on which our understanding of the visible Universe is build. We present a comparison of the surface density of young stars (Sigma(star)) and dust surface density (Sigma(dust)) across NGC 346 (N66) in 115 independent pixels of 6 x 6 pc(2). We find a correlation between Sigma(star) and Sigma(dust) with a considerable scatter. A power-law fit to the data yields a steep relation with an exponent of 2.6 +/- 0.2. We convert Sigma(dust) to gas surface density (Sigma(gas)) and Sigma(star) to star formation rate (SFR) surface densities (Sigma(SFR)), using simple assumptions for the gas-to-dust mass ratio and the duration of star formation. The derived total SFR (4 +/- 1x10(-3) M-circle dot yr(-1)) is consistent with SFR estimated from the Ha emission integrated over the Ha nebula. On small scales the Sigma(SFR) derived using H alpha systematically underestimates the count-based Sigma(SFR), by up to a factor of 10. This is due to ionizing photons escaping the area, where the stars are counted. We find that individual 36 pc(2) pixels fall systematically above integrated disc galaxies in the Schmidt-Kennicutt diagram by on average a factor of similar to 7. The NGC 346 average SFR over a larger area (90 pc radius) lies closer to the relation but remains high by a factor of similar to 3. The fraction of the total mass (gas plus young stars) locked in young stars is systematically high (similar to 10 per cent) within the central 15 pc and systematically lower outside (2 per cent), which we interpret as variations in star formation efficiency. The inner 15 pc is dominated by young stars belonging to a centrally condensed cluster, while the outer parts are dominated by a dispersed population. Therefore, the observed trend could reflect a change of star formation efficiency between clustered and non-clustered star formation.

引用

页码：1847 / 1862

页数：16

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