J/ApJ/849/149 VMC XXVII. Young stellar structures in the LMC (Sun+, 2017)
The VMC survey.
XXVII. Young stellar structures in the LMC's bar star-forming complex.
Sun N.-C., de Grijs R., Subramanian S., Bekki K., Bell C.P.M.,
Cioni M.-R.L., Ivanov V.D., Marconi M., Oliveira J.M., Piatti A.E.,
Ripepi V., Rubele S., Tatton B.L., van Loon J.T.
<Astrophys. J., 849, 149 (2017)>
=2017ApJ...849..149S 2017ApJ...849..149S
ADC_Keywords: Magellanic Clouds; Infrared sources; Surveys
Keywords: infrared: stars ; Magellanic Clouds ; stars: formation
Abstract:
Star formation is a hierarchical process, forming young stellar
structures of star clusters, associations, and complexes over a wide
range of scales. The star-forming complex in the bar region of the
Large Magellanic Cloud is investigated with upper main-sequence stars
observed by the VISTA Survey of the Magellanic Clouds. The upper
main-sequence stars exhibit highly nonuniform distributions. Young
stellar structures inside the complex are identified from the stellar
density map as density enhancements of different significance levels.
We find that these structures are hierarchically organized such that
larger, lower-density structures contain one or several smaller,
higher- density ones. They follow power-law size and mass
distributions, as well as a lognormal surface density distribution.
All these results support a scenario of hierarchical star formation
regulated by turbulence. The temporal evolution of young stellar
structures is explored by using subsamples of upper main-sequence
stars with different magnitude and age ranges. While the youngest
subsample, with a median age of log(τ/yr)=7.2, contains the most
substructure, progressively older ones are less and less
substructured. The oldest subsample, with a median age of
log(τ/yr)=8.0, is almost indistinguishable from a uniform
distribution on spatial scales of 30-300pc, suggesting that the young
stellar structures are completely dispersed on a timescale of ∼100Myr.
These results are consistent with the characteristics of the 30
Doradus complex and the entire Large Magellanic Cloud, suggesting no
significant environmental effects. We further point out that the
fractal dimension may be method dependent for stellar samples with
significant age spreads.
Description:
Data used in this work are from the VMC survey (Cioni+ 2011, II/351),
which is carried out with the Visible and Infrared Survey Telescope
for Astronomy (VISTA). The VMC survey is a multiepoch, uniform, and
homogeneous photometric survey of the Magellanic System (LMC, SMC,
Bridge, and Stream). It uses the near-infrared Y, J, and Ks bands, and
the typical spatial resolution is ∼1" or better.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 42 123 Identified young stellar structures
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See also:
II/351 : VISTA Magellanic Survey (VMC) catalog (Cioni+, 2011)
J/A+AS/104/379 : Integrated Photometry of open clusters (Battinelli+ 1994)
J/A+A/397/473 : HST photometry of M51 cluster (Bik+, 2003)
J/AJ/127/1531 : Star formation history of SMC (Harris+, 2004)
J/AJ/127/1632 : UBVR(UIT) photometry of O and OB stars in SMC (Oey+, 2004)
J/AJ/128/1606 : Magellanic Clouds Photometric Survey: LMC (Zaritsky+, 2004)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/ApJS/178/56 : CO observations of LMC Giant Molecular clouds (Fukui+, 2008)
J/AJ/138/1243 : The star formation history of the LMC (Harris+, 2009)
J/MNRAS/403/996 : Clusters and associations in SMC and LMC (Bonatto+, 2010)
J/ApJ/723/492 : Physical data of GRS molecular clouds (Roman-Duval+, 2010)
J/ApJ/727/64 : Young stellar groups & their massive stars (Kirk+, 2011)
J/A+A/542/A66 : YSOs in 9 LMC star forming regions (Carlson+, 2012)
J/MNRAS/452/3508 : Young stellar structures in NGC 6503 (Gouliermis+, 2015)
J/MNRAS/454/839 : VMC survey. XVI. (Piatti+, 2015)
J/MNRAS/449/639 : VMC survey. XIV. SFR in SMC (Rubele+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/123] Internal index number
5- 6 I2 --- sig [1/10] Significance level (see Figure 4)
8- 15 F8.4 deg RAdeg [28.8/320.5] Right Ascension (J2000) (1)
17- 24 F8.4 deg DEdeg [-82.5/-30] Declination (J2000) (1)
26- 30 F5.1 pc R [2.5/213] Size parameter (2)
32- 37 F6.1 --- N* [4.5/4419.2] Mass; expressed in N* (the number of
upper main-sequence stars in a structure)
39- 42 F4.2 pc-2 SDen [0.01/0.5] Surface density (3)
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Note (1): Of the center of each young stellar structure, defined as:
(RAdeg|DEdeg)=((RAdeg|DEdeg)min+(RAdeg|DEdeg)max)/2, where
(RAdeg|DEdeg)min and (RAdeg|DEdeg)max are the minimum and maximum
Right Ascensions or Declinations of the iso-density contour of
each structure, respectively.
Note (2): The size of each young stellar structure, R, is estimated based on
the radius of a circle that has the same area as that covered by the
isodensity contour of the structure. See section 4.2
Note (3): Σ=N*/A where A is the area of the isodensity contour (see
Section 4.1 and Figure 4).
See section 4.4 for further explanations.
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History:
From electronic version of the journal
References:
Cioni et al. 2011Msngr.144...25C 2011Msngr.144...25C
Cioni et al. Paper I 2011A&A...527A.116C 2011A&A...527A.116C Cat. II/351
Miszalski et al. Paper II 2011A&A...531A.157M 2011A&A...531A.157M
Gullieuszik et al. Paper III 2012A&A...537A.105G 2012A&A...537A.105G
Rubele et al. Paper IV 2012A&A...537A.106R 2012A&A...537A.106R
Ripepi et al. Paper V 2012MNRAS.424.1807R 2012MNRAS.424.1807R Cat. J/MNRAS/424/1807
Cioni et al. Paper VI 2013A&A...549A..29C 2013A&A...549A..29C Cat. J/A+A/549/29
Tatton et al. Paper VII 2013A&A...554A..33T 2013A&A...554A..33T Cat. J/A+A/554/A33
Ripepi et al. Paper VIII 2014MNRAS.437.2307R 2014MNRAS.437.2307R Cat. J/MNRAS/437/2307
Cioni et al. Paper IX 2014A&A...562A..32C 2014A&A...562A..32C
Moretti et al. Paper X 2014MNRAS.437.2702M 2014MNRAS.437.2702M Cat. J/MNRAS/437/2702
Li et al. Paper XI 2014ApJ...790...35L 2014ApJ...790...35L
Piatti et al. Paper XII 2014A&A...570A..74P 2014A&A...570A..74P
Ripepi et al. Paper XIII 2015MNRAS.446.3034R 2015MNRAS.446.3034R Cat. J/MNRAS/446/3034
Rubele et al. Paper XIV 2015MNRAS.449..639R 2015MNRAS.449..639R Cat. J/MNRAS/449/639
Piatti et al. Paper XV 2015MNRAS.450..552P 2015MNRAS.450..552P
Piatti et al. Paper XVI 2015MNRAS.454..839P 2015MNRAS.454..839P Cat. J/MNRAS/454/839
Cioni et al. Paper XVII 2016A&A...586A..77C 2016A&A...586A..77C
Zhang et al. Paper XVIII 2015ApJ...815...95Z 2015ApJ...815...95Z
Ripepi et al. Paper XIX 2016ApJS..224...21R 2016ApJS..224...21R Cat. J/ApJS/224/21
Moretti et al. Paper XX 2016MNRAS.459.1687M 2016MNRAS.459.1687M Cat. J/MNRAS/459/1687
Piatti et al. Paper XXI 2016MNRAS.460..383P 2016MNRAS.460..383P
Sun et al. Paper XXII 2017ApJ...835..171S 2017ApJ...835..171S
Marconi et al. Paper XXIII 2017MNRAS.466.3206M 2017MNRAS.466.3206M
Subramanian et al. Paper XXIV 2017MNRAS.467.2980S 2017MNRAS.467.2980S
Ripepi et al. Paper XXV 2017MNRAS.472..808R 2017MNRAS.472..808R
Muraveva et al. Paper XXVI 2018MNRAS.473.3131M 2018MNRAS.473.3131M
Sun et al. Paper XXVII 2017ApJ...849..149S 2017ApJ...849..149S This catalog
Niederhofer et al. Paper XXVIII 2018A&A...612A.115N 2018A&A...612A.115N
Sun et al. Paper XXIX 2018ApJ...858...31S 2018ApJ...858...31S Cat. J/ApJ/858/31
Niederhofer et al. Paper XXX 2018A&A...613L...8N 2018A&A...613L...8N
Rubele et al. Paper XXXI 2018MNRAS.478.5017R 2018MNRAS.478.5017R
Zivkov et al. Paper XXXII 2018A&A...620A.143Z 2018A&A...620A.143Z
Groenewegen et al. Paper XXXIII 2019A&A...622A..63G 2019A&A...622A..63G
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Jun-2018