J/ApJ/909/121 Young star clusters in NGC1313 with HST obs. (Messa+, 2021)
Looking for obscured young star clusters in NGC 1313.
Messa M., Calzetti D., Adamo A., Grasha K., Johnson K.E., Sabbi E.,
Smith L.J., Bajaj V., Finn M.K., Lin Z.
<Astrophys. J., 909, 121 (2021)>
=2021ApJ...909..121M 2021ApJ...909..121M
ADC_Keywords: Clusters, open; Galaxies, nearby; Stars, ages; Stars, masses;
Extinction; Ultraviolet; Optical; Infrared
Keywords: Young star clusters ; Compact H II region ; Star formation ;
Interstellar dust extinction ; Spiral galaxies
Abstract:
Using recently acquired Hubble Space Telescope NIR observations (J,
Paβ, and H bands) of the nearby galaxy NGC 1313, we investigate
the timescales required by a young star cluster to emerge from its
natal cloud. We search for extincted star clusters, potentially
embedded in their natal cloud as either (1) compact sources in regions
with high Hα/Paβ extinctions or (2) compact HII regions
that appear as point-like sources in the Paβ emission map. The
NUV-optical-NIR photometry of the candidate clusters is used to derive
their ages, masses, and extinctions via a least-χ2 spectral
energy distribution broad- and narrowband fitting process. The
100 clusters in the final samples have masses in the range
log10(M/M☉)=2.5-3.5 and moderate extinctions, E(B-V)≲1.0mag.
Focusing on the young clusters (0-6Myr), we derive a weak correlation
between extinction and age of the clusters. Almost half of the
clusters have low extinctions, E(B-V)<0.25mag, already at very young
ages (≤3Myr), suggesting that dust is quickly removed from clusters.
A stronger correlation is found between the morphology of the nebular
emission (compact, partial or absent, both in Hα and Paβ)
and cluster age. Relative fractions of clusters associated with a
specific nebular morphology are used to estimate the typical
timescales for clearing the natal gas cloud, resulting in between
3 and 5Myr, ∼1Myr older than what was estimated from NUV-optical-based
cluster studies. This difference hints at a bias for
optical-only-based studies, which James Webb Space Telescope will
address in the coming years.
Description:
On 2017-11-26, 2018-09-04, we acquired near-infrared (NIR) photometry
of NGC 1313 with the WFC3-IR camera, on board HST, covers two
pointings of the galaxy with two broadband (F110W and F160W) and one
narrowband (F128N) filters (GO program 15330; PI D. Calzetti).
In this study, we take advantage of the broad archival HST wavelength
coverage of NGC 1313; in detail, we use observations in five filters
from the Legacy ExtraGalactic UV Survey (LEGUS;
Calzetti+ 2015AJ....149...51C 2015AJ....149...51C) covering the NUV-optical range with
broadband filters (F275W, F336W, F435W, F555W, and F814W; GO 9796,
9774, 10210 and 13364) and in two additional filters from the
LEGUS-Hα follow-up survey (GO 13773; PI R. Chandar) observing
the galaxy with a narrow filter covering the Hα emission-line
(F657N) and a medium-band filter sampling the line-free continuum
(F547M). In total, we have 10 filters spanning the wavelength range
NUV-NIR, including two filters for the observation of the two hydrogen
recombination lines Hα and Paβ.
Objects:
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RA (ICRS) DE Designation(s)
----------------------------------------------------------
03 18 16.05 -66 29 53.7 NGC 1313 = ESO-LV 82-0110
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 85 101 Catalog of detected sources included in the
final cluster samples
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/ApJ/559/864 : Extragalactic ultracompact H II regions (Johnson+, 2001)
J/ApJS/178/247 : Hα and [NII] survey in local 11 Mpc (Kennicutt+, 2008)
J/AJ/138/332 : LEDA CMD/tip of the red giant branch (Jacobs+, 2009)
J/MNRAS/452/525 : M83 young star cluster light profiles (Ryon+, 2015)
J/ApJ/827/33 : PHAT. XVI. Star cluster masses and ages (Johnson+, 2016)
J/A+A/601/A146 : M33 mol. clouds and young stellar clusters (Corbelli+, 2017)
J/ApJ/841/92 : Young massive star clusters in 2 LEGUS galaxies (Ryon+, 2017)
J/ApJS/245/14 : 8um cores in spiral arms of nearby gal. (Elmegreen+, 2019)
J/ApJ/895/71 : 8um Cores in NGC 891, NGC 3628 and IC 5052 (Elmegreen+, 2020)
J/ApJ/889/154 : LEGUS & Ha-LEGUS obs. of NGC4449 clusters (Whitmore+, 2020)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- ID Object identifier (<[MCA2021] CNNN> in Simbad)
6- 13 F8.5 deg RAdeg [49.49/49.67] Right Ascension (J2000)
15- 23 F9.5 deg DEdeg [-66.53/-66.46] Declination (J2000)
25 A1 --- l_Reff Upper limit flag on Reff (1)
26- 29 F4.2 pc Reff [0.59/7.2] Effective radius
31- 34 F4.2 pc e_Reff [0.03/6]? Uncertainty in Reff
36- 38 I3 Myr Age [1/401] Age
40- 42 I3 Myr b_Age [1/401] Minimum 1σ from best-fit in Age
44- 46 I3 Myr B_Age [1/503] Maximum 1σ from best-fit in Age
48- 51 F4.2 mag EBV [0/2.5] Color excess E(B-V)
53- 56 F4.2 mag b_EBV [0/2.5] Minimum 1σ from best-fit in EBV
58- 61 F4.2 mag B_EBV [0.01/2.5] Maximum 1σ from best-fit in EBV
63- 66 F4.2 [Msun] logM [2/4.8] Log of the mass
68- 71 F4.2 [Msun] b_logM [1.7/4.7] Minimum 1σ from best-fit in logM
73- 76 F4.2 [Msun] B_logM [2.3/4.9] Maximum 1σ from best-fit in logM
78- 82 F5.1 --- Chi2 [0.2/246] Reduced chi squared
84- 85 A2 --- Cat Final catalog containing the source (2)
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Note (1): Effective radii of 0.59pc without uncertainties are to be considered
upper limits. See section 4.2 and Appendix A for more details.
Note (2): We extract a catalog of possible candidates in two different ways:
(1) the first selection is made by using a map of nebular extinction
derived from Hα and Paβ observations. Subregions of the
galaxy where the extinction is higher than AV≥0.8mag were searched
for sources in the F814W filter with counterparts in the NIR filters;
(2) with a complementary approach, we select sources with compact
Paβ emission within the entire galaxy. The sources in the two
resulting catalogs, named ExtmapCat and PBcompactCat, respectively,
are analyzed photometrically and via a least-χ2 broad- and
narrowband SED fit, in order to derive their ages, masses, and
extinctions.
Catalog as follows:
E = ExtmapCat-final (17 occurrences);
P = PBcompactCat-final (55 occurrences);
EP = source contained in both (29 occurrences).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 09-Aug-2022