2025ApJ...983..137R

Query : 2025ApJ...983..137R

2025ApJ...983..137R - Astrophys. J., 983, 137 (2025/April-3)

Tracing the Earliest Stages of Star and Cluster Formation in 19 Nearby Galaxies with PHANGS-JWST and HST: Compact 3.3 μm Polycyclic Aromatic Hydrocarbon Emitters and Their Relation to the Optical Census of Star Clusters.

RODRIGUEZ M.J., LEE J.C., INDEBETOUW R., WHITMORE B.C., MASCHMANN D., WILLIAMS T.G., CHANDAR R., BARNES A.T., GNEDIN O.Y., SANDSTROM K.M., ROSOLOWSKY E., LEROY A.K., THILKER D.A., KIM H., SUN J., KLESSEN R.S., GROVES B., WOFFORD A., BOQUIEN M., DALE D.A., UBEDA L., LARSON K.L., GRASHA K., JOHNSON K.E., LEVY R.C., BIGIEL F., HASSANI H. and SARBADHICARY S.K.

Abstract (from CDS):

The earliest stages of star and cluster formation are hidden within dense cocoons of gas and dust, limiting their detection at optical wavelengths. With the unprecedented infrared capabilities of JWST, we can now observe dust-enshrouded star formation with ∼10 pc resolution out to ∼20 Mpc. Early findings from PHANGS-JWST suggest that 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission can identify star clusters in their dust-embedded phases. Here, we extend this analysis to 19 galaxies from the PHANGS-JWST Cycle 1 Treasury survey, providing the first characterization of compact sources exhibiting 3.3 μm PAH emission across a diverse sample of nearby star-forming galaxies. We establish a selection criteria based on a median color threshold of F300M - F335M = 0.67 at F335M = 20 and identify 1816 sources. These sources are predominantly located in dust lanes, spiral arms, rings, and galaxy centers, with ∼87% showing concentration indices (CIs) similar to optically detected star clusters. Comparison with the PHANGS-HST catalogs suggests that PAH emission fades within ∼3 Myr. The Hα equivalent width of PAH emitters is 1-2.8 times higher than that of young PHANGS-HST clusters, providing evidence that PAH emitters are on average younger. Analysis of the bright portions of luminosity functions (which should not suffer from incompleteness) shows that young dusty clusters may increase the number of optically visible ≤3 Myr old clusters in PHANGS-HST by a factor between ∼1.8× and 8.5×.

Abstract Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Star formation - Young star clusters - Polycyclic aromatic hydrocarbons - Star clusters - Spiral galaxies - James Webb Space Telescope - Interstellar dust

Simbad objects: 27

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Number of rows : 27
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 IC 1623 IG 01 07 47.24 -17 30 25.0   15       ~ 338 2
2 M 74 G 01 36 41.7451236624 +15 47 01.107512304 10.52 10.00 9.46 9.16   ~ 1934 1
3 NGC 1087 H2G 02 46 25.1550134904 -00 29 55.457857644   11.5   11.4 11.5 ~ 379 0
4 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 7988 0
5 NGC 1300 Sy2 03 19 41.0462219928 -19 24 40.187565432   11.16 10.42 9.90 10.7 ~ 616 0
6 NGC 1365 Sy1 03 33 36.458 -36 08 26.37 10.48 10.08 9.63 8.79 9.7 ~ 1987 2
7 NGC 1385 EmG 03 37 28.323 -24 30 04.60 11.28 11.50 10.94 10.45 11.7 ~ 318 2
8 NGC 1433 Sy2 03 42 01.4847418992 -47 13 18.929092656   10.84 9.99 9.61 10.2 ~ 447 0
9 NGC 1512 GiP 04 03 54.281 -43 20 55.86 11.30 11.43 10.54 10.37   ~ 457 1
10 NGC 1566 Sy1 04 20 00.3968473248 -54 56 16.624708764 10.29 10.19 9.73 9.21 10.1 ~ 1051 2
11 NGC 1672 SyG 04 45 42.552 -59 14 50.68 10.29 10.53 9.68 9.53 10.2 ~ 461 2
12 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
13 NAME 30 Dor Nebula SFR 05 38 36.0 -69 05 11           ~ 1276 2
14 NGC 2070 Cl* 05 38 42 -69 06.0     7.25     ~ 406 1
15 RMC 136 Cl* 05 38 42.396 -69 06 03.36   5.81 5.40     ~ 2236 2
16 NGC 2835 EmG 09 17 52.8523921416 -22 21 16.839119700   11.03   10.32 10.9 ~ 285 0
17 M 82 AGN 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 6156 6
18 NGC 3256 Sy2 10 27 51.284 -43 54 13.55   11.83 11.33 10.62 11.9 ~ 920 2
19 M 95 GiP 10 43 57.7313485800 +11 42 13.301191332 10.71 10.51 9.73 9.48   ~ 1238 2
20 M 66 AGN 11 20 15.0 +12 59 29 9.85 9.65 8.92     ~ 1509 4
21 M 99 H2G 12 18 49.625 +14 24 59.36 10.45 10.44 9.87     ~ 1004 2
22 M 61 Sy2 12 21 54.9282582888 +04 28 25.597367184 10.07 10.18 9.65     ~ 1084 1
23 M 100 AGN 12 22 54.9299993592 +15 49 20.296257960 10.04 10.05 9.35     ~ 1963 2
24 NGC 4535 H2G 12 34 20.3443516704 +08 11 51.908488116   11.1       ~ 679 0
25 NGC 5068 AG? 13 18 54.807 -21 02 20.76 11.24 10.53 10.01 9.78 10.1 ~ 354 0
26 NGC 7496 Sy2 23 09 47.2876854912 -43 25 40.279652796   11.92 13.90 10.95 11.5 ~ 350 1
27 IC 5332 GiG 23 34 27.488 -36 06 03.89 11.59 11.27 10.72 10.50 11.2 ~ 216 0

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