J/A+A/693/A120 Westerlund 1 NIRCam/MIRI images (Guarcello+, 2025)
EWOCS-III:
JWST observations of the supermassive star cluster Westerlund 1.
Guarcello M.G., Almendros-Abad V., Lovell J.B., Monsch K., Muzic K.,
Martinez-Galarza J.R., Drake J.J., Anastasopoulou K., Andersen M.,
Argiroffi C., Bayo A., Bonito R., Capela D., Damiani F., Gennaro M.,
Ginsburg A., Grebel E.K., Hora J.L., Moraux E., Najarro F., Negueruela I.,
Prisinzano L., Richardson N.D., Ritchie B., Robberto M., Rom T., Sabbi E.,
Sciortino S., Umana G., Winter A., Wright N.J., Zeidler P.
<Astron. Astrophys. 693, A120 (2025)>
=2025A&A...693A.120G 2025A&A...693A.120G (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Infrared sources
Keywords: circumstellar matter - stars: low-mass - stars: massive -
stars: pre-main sequence - stars: winds, outflows
Abstract:
The typically large distances, extinction, and crowding of Galactic
supermassive star clusters (stellar clusters more massive than
104M☉) have so far hampered the identification of their very
low mass members, required to extend our understanding of star and
planet formation, and early stellar evolution, to the extremely
energetic star-forming environment typical of starbursts. This
situation has now evolved thanks to the James Webb Space Telescope
(JWST), and its unmatched resolution and sensitivity in the infrared.
In this paper, the third of the series of the Extended Westerlund 1
and 2 Open Clusters Survey (EWOCS), we present JWST/NIRCam and
JWST/MIRI observations of the supermassive star cluster Westerlund 1.
These observations are specifically designed to unveil the cluster
members down to the brown dwarf mass regime, and to allow us to select
and study the protoplanetary disks in the cluster and to study the
mutual feedback between the cluster members and the surrounding
environment.
Westerlund 1 was observed as part of JWST GO-1905 for 23.6 hours. The
data have been reduced using the JWST calibration pipeline, together
with specific tools necessary to remove artifacts, such as the 1/f
random noise in NIRCam images. Source identification and photometry
were performed with DOLPHOT.
The MIRI images show a plethora of different features. Diuse nebular
emission is observed around the cluster, which is typically composed
of myriads of droplet-like features pointing toward the cluster center
or the group of massive stars surrounding the Wolf-Rayet star W72/A. A
long pillar is also observed in the northwest. The MIRI images also
show resolved shells and outflows surrounding the M-type supergiants
W20, W26, W75, and W237, the sgB[e] star W9 and the yellow hypergiant
W4. Some of these shells have been observed before at other
wavelengths, but never with the level of detail provided by JWST. The
color-magnitude diagrams built using the NIRCam photometry show a
clear cluster sequence, which is marked in its upper part by the 1828
NIRCam stars with X-ray counterparts. NIRCam observations using the
F115W filter have reached the 23.8 mag limit with 50% completeness
(roughly corresponding to a 0.06M☉ brown dwarf).
Description:
We observed Westerlund 1 with NIRCam using five wide and
six narrow filters and with MIRI with three filters in program GO 1905
(PI: Guarcello).
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------
16 47 02.40 -45 51 07.2 Westerlund 1 = ESO 277-12
----------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 166 2 List of fits mosaics
fits/* . 2 Individual fits mosaics
--------------------------------------------------------------------------------
See also:
J/A+A/632/A38 : Westerlund 1 reduced images of radio emission (Andrews+, 2019)
J/A+A/682/A49 : EWOCS-I. X-ray sources in Westerlund 1 (Guarcello+, 2024)
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 35 I6 Kibyte size Size of FITS file
37- 78 A42 --- FileName Name of FITS file, in subdirectory fits
80-166 A87 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Mario Guarcello, mario.guarcello(at)inaf.it
History:
Guarcello et al., Paper I 2024A&A...682A..49G 2024A&A...682A..49G Cat. J/A+A/682/A49
Guarcello et al., Paper II 2024A&A...690A..25A 2024A&A...690A..25A
(End) Patricia Vannier [CDS] 10-Dec-2024