| 1. |
- Della Bruna, Lorenza, et al.
(författare)
-
Studying the ISM at ∼10 pc scale in NGC 7793 with MUSEII : Constraints on the oxygen abundance and ionising radiation escape (Corrigendum)
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 663
-
Tidskriftsartikel (refereegranskat)abstract
- Table 3 in the original paper reports inaccurate values of Q0exp;YSC and Q0obs(and hence of the related quantities Qexp;tot, Qexptot=Qobs, and fesc). The error in Q0exp;YSC results from a mistake in the sampling of the cluster probability distribution functions (PDFs), whereas Q0obswas mistakenly computed from non-dereddened values of L(Hα). In Table 1 we provide a revised version of the original Table 3, and in Figs. 1 and 2 we show revised versions of the original Figs. 10 and 11. The revised values do not change any of the conclusions stated in the original paper. In the following we provide revised text for the affected sections. (Figure Presented).
|
|
| 2. |
- Linden, S. T., et al.
(författare)
-
Star Cluster Formation and Evolution in M101 : An Investigation with the Legacy Extragalactic UV Survey
- 2022
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 935:2
-
Tidskriftsartikel (refereegranskat)abstract
- We present Hubble Space Telescope WFC3/UVIS (F275W, F336W) and ACS/WFC optical (F435W, F555W, and F814W) observations of the nearby grand-design spiral galaxy M101 as part of the Legacy Extragalactic UV Survey (LEGUS). Compact sources detected in at least four bands were classified by both human experts and the convolutional neural network StarcNet. Human experts classified the 2351 brightest sources, retrieving N-c = 965 star clusters. StarcNet, trained on LEGUS data not including M101, classified all 4725 sources detected in four bands, retrieving N-c = 2270 star clusters. The combined catalog represents the most complete census to date of compact star clusters in M101. We find that for the 2351 sources with both a visual- and machine-learning classification StarcNet is able to reproduce the human classifications at high levels of accuracy (similar to 80%-90%), which is equivalent to the level of agreement between human classifiers in LEGUS. The derived cluster age distribution implies a disruption rate of dN/d tau proportional to tau(-0.45 +/- 0.14) over 10(7) < tau < 10(8.5) yr for cluster masses >= 10(3.55) M-circle dot for the central region of M101 and dN/d tau proportional to tau(-0.02 +/- 0.15) for cluster masses >= 10(3.38) M-circle dot in the northwest region of the galaxy. The trends we recover are weaker than those of other nearby spirals (e.g., M51) and starbursts, consistent with the M101 environment having a lower-density interstellar medium, and providing evidence in favor of environmentally dependent cluster disruption in the central, southeast, and northwest regions of M101.
|
|
| 3. |
- Messa, Matteo, 1988-, et al.
(författare)
-
Multiply lensed star forming clumps in the A521-sys1 galaxy at redshift 1
- 2022
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 516:2, s. 2420-2443
-
Tidskriftsartikel (refereegranskat)abstract
- We study the population of star-forming clumps in A521-sys1, a z=1.04 system gravitationally lensed by the foreground (z=0.25) cluster Abell 0521. The galaxy presents one complete counter-image with a mean magnification of μ∼4 and a wide arc containing two partial images of A521-sys1 with magnifications reaching μ>20, allowing the investigations of clumps down to scales of Reff<50 pc. We identify 18 unique clumps with a total of 45 multiple images. Intrinsic sizes and UV magnitudes reveal clumps with elevated surface brightnesses comparable to similar systems at redshifts z≳1.0. Such clumps account for ∼40per cent of the galaxy UV luminosity implying a significant fraction of the recent star-formation activity is taking place there. Clump masses range from 106 to 109 M⊙ and sizes from tens to hundreds of parsec resulting in mass surface densities from 10 to 103 M⊙ pc−2 with a median of ∼102 M⊙ pc−2. These properties suggest that we detect star formation taking place across a wide range of scale from cluster aggregates to giant star-forming complexes. We find ages of less than 100 Myr consistent with clumps being observed close to their natal region. The lack of galactocentric trends with mass, mass density, or age and the lack of old migrated clumps can be explained either by dissolution of clumps after few ∼100 Myr or by stellar evolution making them fall below the detectability limits of our data.
|
|
| 4. |
- Orozco-Duarte, Rogelio, et al.
(författare)
-
Synthetic photometry of OB star clusters with stochastically sampled IMFs : analysis of models and HST observations
- 2022
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 509:1, s. 522-549
-
Tidskriftsartikel (refereegranskat)abstract
- We present a pilot library of synthetic NUV, U, B, V, and I photometry of star clusters with stochastically sampled IMFs and ionized gas for initial masses, Mi = 103, 104, and 105 M⊙; t = 1, 3, 4, and 8 Myr; Z = 0.014 and Z = 0.002; and log(US) = −2 and −3. We compare the library with predictions from deterministic models and observations of isolated low-mass (<104 M⊙) star clusters with co-spatial compact H II regions. The clusters are located in NGC 7793, one of the nearest galaxies observed as part of the HST LEGUS and Hα-LEGUS surveys. (1) For model magnitudes that only account for the stars: (a) the residual |deterministic mag - median stochastic mag| can be ≥0.5 mag, even for Mi = 105 M⊙; and (b) the largest spread in stochastic magnitudes occurs when Wolf–Rayet stars are present. (2) For Mi = 105 M⊙: (a) the median stochastic mag with gas can be >1.0 mag more luminous than the median stochastic magnitude without gas; and (b) nebular emission lines can contribute with >50 per cent and >30 per cent to the total emission in the V and I bands, respectively. (3) Age-dating OB-star clusters via deterministic tracks in the U-B versus V-I plane is highly uncertain at Z = 0.014 for Mi ∼ 103 M⊙ and Z = 0.002 for Mi ∼ 103–105 M⊙. (4) For low-mass clusters, the V-band extinction derived with stochastic models significantly depends on the value of log(US). (5) The youngest clusters tend to have higher extinction. (6) The majority of clusters have multi-peaked age PDFs. (7) Finally, we discuss the importance of characterizing the true variance in the number of stars per mass bin in nature.
|
|
| 5. |
- Sirressi, Mattia, et al.
(författare)
-
CLusters in the UV as EngineS (CLUES). I. Survey Presentation and FUV Spectral Analysis of the Stellar Light
- 2022
-
Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 164:5
-
Tidskriftsartikel (refereegranskat)abstract
- The CLusters in the Uv as EngineS (CLUES) survey is a Cosmic Origins Spectrograph (COS) campaign aimed at acquiring the 1130–1770 Å rest-frame spectroscopy of very young (<20 Myr) and massive (>104 M⊙) star clusters in galaxies that are part of the Hubble treasury program Legacy ExtraGalactic UV Survey. In this first paper of a series, we describe the CLUES sample consisting of 20 young star clusters and report their physical properties as derived by both multiwavelength photometry and far-UV (FUV) spectroscopy with Hubble Space Telescope. Thanks to the synergy of the two different data sets, we build a coherent picture of the diverse stellar populations found in each region (with sizes of 40–160 pc). We associate the FUV-brightest stellar population to the central targeted star cluster and the other modeled population to the diffuse stars that are included in the COS aperture. We observe better agreement between photometric and spectroscopic ages for star clusters younger than 5 Myr. For clusters older than 5 Myr, photometry and spectroscopy measurements deviate, with the latter producing older ages, due to the degeneracy of photometric models. FUV spectroscopy enables us to better constrain the stellar metallicities, a parameter that optical colors are insensitive to. Finally, the derived E(B − V) are quite similar, with a tendency for FUV spectroscopy to favor solutions with higher extinctions. The recovered masses are in agreement within a factor of 2 for all of the clusters.
|
|
