THE 1.1 mm CONTINUUM SURVEY OF THE SMALL MAGELLANIC CLOUD: PHYSICAL PROPERTIES AND EVOLUTION OF THE DUST-SELECTED CLOUDS*

Takekoshi, Tatsuya; Minamidani, Tetsuhiro; Komugi, Shinya; Kohno, Kotaro; Tosaki, Tomoka; Saito, Kazuo; Müller, Erik; Mizuno, N.; Kawamura, Akiko; Onishi, Toshikazu; Fukui, Y.; Ezawa, H.; Oshima, Tai; Scott, K. S.; Austermann, J. E.; Matsuo, Hiroshi; Aretxaga, I.; Hughes, D. H.; Kawabe, Ryohei; Wilson, Grant; Yun, Min S.

doi:10.3847/1538-4357/835/1/55

Cited by 14 publications

(26 citation statements)

References 82 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the same time, widely extended astronomical signals, which are also correlated among bolometer pixels, are also removed. Simulations of reproducibility of extended sources using Gaussian model sources show that > 60% of the total flux density and ∼ 100% of peak flux density are recovered for compact objects smaller than < 3 full-width at half-maximum (FWHM) in our cases, which corresponds to the typical size of the detected objects in the observation region, as shown in Section 3 (Komugi et al 2011;Shimajiri et al 2011;Takekoshi et al 2017).…”

Section: Aztec/aste Observationsupporting

confidence: 64%

“…The FWHM of the point response function (PRF) after the FRUIT procedure was 40 , which corresponds to 12 pc. FRUIT also added an uncertainty of 10% to the photometry of the detected objects (Takekoshi et al 2017). The total photometric accuracy was estimated to be 13% by the root sum square of the flux calibration and FRUIT photometric accuracy.…”

Section: Aztec/aste Observationmentioning

confidence: 99%

“…The 1.1 mm objects identified by Takekoshi et al (2017, hereafter wide-survey objects) are potential candidates of dense gas clouds that are forming or about to form massive stars. In the wide-survey objects, only NE-1 was detected as…”

Section: Comparison With the Wide-survey Objectsmentioning

confidence: 99%

“…We did not include the three objects in the NEdeep samples located at the edge of the 1.1 mm images, and N88-1 of the wide-survey objects in the statistics. Takekoshi et al (2017) assumed a fixed β = 1.2 for estimating the dust temperature and mass of the wide-survey objects. Here, we estimated the average and standard deviation values of β = 1.3 ± 0.3 for the NEdeep objects, and this difference between free β and β = 1.2 fits causes the systematic average differences of 5% and 8% for dust temperature and mass (except for upper limit values) estimate, respectively.…”

Section: Comparison With the Wide-survey Objectsmentioning

confidence: 99%

“…The dust temperature of the NEdeep objects may be slightly lower than that of the wide-survey objects. The difference of star forming activity between the NEdeep and wide-survey objects would explain this difference, because the wide-survey objects include very active star forming regions such as Lirs49, SMCB-2N, and N66, which show the dust temperature of ∼ 40 K (Takekoshi et al 2017). We avoid further discussion regarding the comparison with the wide-survey objects here, because of the difference of the SED fit models.…”

Section: Comparison With the Wide-survey Objectsmentioning

confidence: 99%

See 4 more Smart Citations

The Dust-selected Molecular Clouds in the Northeast Region of the Small Magellanic Cloud*

Takekoshi

Minamidani

Komugi

et al. 2018

ApJ

Self Cite

View full text Add to dashboard Cite

We present a high-sensitivity (1σ < 1.6 mJy beam −1 ) continuum observation in a 343 arcmin 2 area of the northeast region in the Small Magellanic Cloud at a wavelength of 1.1 mm, conducted using the AzTEC instrument on the ASTE telescope. In the observed region, we identified 20 objects by contouring 10σ emission. Through spectral energy distribution (SED) analysis using 1.1 mm, Herschel, and Spitzer data, we estimated the gas masses of 5 × 10 3 -7 × 10 4 M , assuming a gas-to-dust ratio of 1000. Dust temperature and the index of emissivity were also estimated as 18-33 K and 0.9-1.9, respectively, which are consistent with previous low resolution studies. The relation between dust temperature and the index of emissivity shows a weak negative linear correlation. We also investigated five CO-detected dust-selected clouds in detail. The total gas masses were comparable to those estimated from the Mopra CO data, indicating that the assumed gas-to-dust ratio of 1000 and the X CO factor of 1 × 10 21 cm −2 (K km s −1 ) −1 , with uncertainties of a factor of 2, are reliable for the estimation of the gas masses of molecular or dust-selected clouds. Dust column density showed good spatial correlation with CO emission, except for an object that associates with bright young stellar objects. The 8 µm filamentary and clumpy structures also showed similar spatial distribution with the * Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

show abstract

Section: Aztec/aste Observationsupporting

confidence: 64%

Section: Aztec/aste Observationmentioning

confidence: 99%

Section: Comparison With the Wide-survey Objectsmentioning

confidence: 99%

Section: Comparison With the Wide-survey Objectsmentioning

confidence: 99%

Section: Comparison With the Wide-survey Objectsmentioning

confidence: 99%

See 3 more Smart Citations

The Dust-selected Molecular Clouds in the Northeast Region of the Small Magellanic Cloud*

Takekoshi

Minamidani

Komugi

et al. 2018

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

A dearth of young and bright massive stars in the Small Magellanic Cloud

Schootemeijer

Langer

Lennon

et al. 2021

A&A

View full text Add to dashboard Cite

Context. Massive star evolution at low metallicity is closely connected to many fields in high-redshift astrophysics, but is poorly understood so far. Because of its metallicity of ∼0.2 Z⊙, its proximity, and because it is currently forming stars, the Small Magellanic Cloud (SMC) is a unique laboratory in which to study metal-poor massive stars. Aims. We seek to improve the understanding of this topic using available SMC data and a comparison to stellar evolution predictions. Methods. We used a recent catalog of spectral types in combination with Gaia magnitudes to calculate temperatures and luminosities of bright SMC stars. By comparing these with literature studies, we tested the validity of our method, and using Gaia data, we estimated the completeness of stars in the catalog as a function of luminosity. This allowed us to obtain a nearly complete view of the most luminous stars in the SMC. We also calculated the extinction distribution, the ionizing photon production rate, and the star formation rate. Results. Our results imply that the SMS hosts only ∼30 very luminous main-sequence stars (M ≥ 40 M⊙; L ≳ 3 ⋅ 105 L⊙), which are far fewer than expected from the number of stars in the luminosity range 3 ⋅ 104 < L/L⊙ < 3 ⋅ 105 and from the typically quoted star formation rate in the SMC. Even more striking, we find that for masses above M ≳ 20 M⊙, stars in the first half of their hydrogen-burning phase are almost absent. This mirrors a qualitatively similar peculiarity that is known for the Milky Way and Large Magellanic Cloud. This amounts to a lack of hydrogen-burning counterparts of helium-burning stars, which is more pronounced for higher luminosities. We derived the H I ionizing photon production rate of the current massive star population. It agrees with the H α luminosity of the SMC. Conclusions. We argue that a declining star formation rate or a steep initial mass function are unlikely to be the sole explanations for the dearth of young bright stars. Instead, many of these stars might be embedded in their birth clouds, although observational evidence for this is weak. We discuss implications for the role that massive stars played in cosmic reionization, and for the top end of the initial mass function.

show abstract

CO(2−1) survey at 9 pc resolution in the Small Magellanic Cloud

P.¹,

M.²,

Bolatto³

et al. 2023

A&A

View full text Add to dashboard Cite

Context. The Small Magellanic Cloud (SMC) is the closest low-metallicity galaxy to the Milky Way where the dynamical state of molecular clouds can be analyzed. Aims. Our aim is to present a CO(2−1) survey at ~9 pc resolution obtained with the Atacama Pathfinder Experiment telescope in an extensive region (~0.4kpc2) of the SMC and uniformly characterize the properties of the SMC clouds. Methods. We used the CPROPS algorithm to identify the molecular clouds and estimate their main CO properties. We analyzed the characteristics of the SMC clouds by studying the scaling relations between the radii, velocity dispersions, luminosities, and virial masses. We also analyzed the mass spectrum of the SMC through the cumulative mass distribution. We used the dust-based total gas masses of SMC clouds presented in the literature to analyze the stability of the molecular clouds and also to estimate the CO-to-H2 conversion factor for the SMC. We used young stellar objects (YSOs) and HII region catalogs in the literature and IR observations in public databases to inspect the star-forming regions in the SMC. Results. We identified 177 molecular clouds within the SMC, of which 124 clouds are fully resolved with signal-to-noise ratios ≳5. We found that the CO luminosity of the identified clouds is (1.3 ± 0.2) × 105 K kms−1 pc2 (representing at least 70% of the total CO luminosity of the region) and the corresponding gas mass from virial determination is Mgas = (1.5 ± 0.5) × 106 M⊙. The scaling relationships show that the SMC clouds are (on average) less turbulent and less luminous than their inner Milky Way counterparts of similar size by a factor of approximately two and three, respectively, while for a fixed linewidth, the SMC clouds are overluminous by a factor of approximately 3.5. We found that the mass spectra of the SMC based on both the luminous mass and the virial mass are steeper than dN/dM ∝ M−2, suggesting that most of the molecular mass of the SMC is contained in low-mass clouds. Using the virial masses of the SMC CO clouds identified by CPROPS, we derived a CO-to-H2 conversion factor of αCOvir = 10.5 ± 5 M⊙ (K km s−1 pc2)−1, adopting the measured SMC CO(2−1)/CO(1−0) ratio of one. Regarding the dust clouds for which we had identified the corresponding CO emission, we determined an upper limit of the dust-based conversion factor for the SMC of αCOdust = 28 ± 15 M⊙ (Kkm s−1 pc2)−1 at 12 pc resolution. These conversion factors, determined by two alternative methods, are about 2.5 and 6.5 times larger than the canonical Galactic conversion factor. For molecular clouds where there is both a dust and a virial mass, we found that the clouds appear to be in approximate gravitational virial equilibrium. Finally, we found that about half of the clouds identified by CPROPS are associated with ongoing star formation, either YSOs or HII regions, but also that close to half the clouds are not. Most of the YSOs in the clouds are in their first evolutive stages.

show abstract

THE 1.1 mm CONTINUUM SURVEY OF THE SMALL MAGELLANIC CLOUD: PHYSICAL PROPERTIES AND EVOLUTION OF THE DUST-SELECTED CLOUDS*

Cited by 14 publications

References 82 publications

The Dust-selected Molecular Clouds in the Northeast Region of the Small Magellanic Cloud*

The Dust-selected Molecular Clouds in the Northeast Region of the Small Magellanic Cloud*

A dearth of young and bright massive stars in the Small Magellanic Cloud

CO(2−1) survey at 9 pc resolution in the Small Magellanic Cloud

Contact Info

Product

Resources

About