J/A+A/709/A212 JWST observations of Terzan 5 (Zullo+, 2026)
The multi-age stellar populations of Terzan 5 as revealed by JWST.
Zullo G., Pallanca C., Ferraro F.R., Lanzoni B., Origlia L., Massari D.,
Dalessandro E., Fanelli C., Cadelano M., Vesperini E., Crociati C.,
Rich R.M., Valenti E.
<Astron. Astrophys. 709, A212 (2026)>
=2026A&A...709A.212Z 2026A&A...709A.212Z (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Photometry, infrared
Keywords: techniques: photometric - Hertzsprung-Russell and C-M diagrams -
Galaxy: bulge - Galaxy: stellar content -
globular clusters: individual: Terzan 5
Abstract:
The James Webb Space Telescope provides an exciting opportunity to
investigate stellar systems located in heavily obscured regions like
the Galactic bulge. Possibly the most enigmatic among them is
Terzan 5: long classified as a globular cluster, it is now known to
host distinct stellar populations with different iron abundances,
ranging approximately from [Fe/H]=-0.8 to [Fe/H]=+0.3dex. Indeed, the
chemical and structural properties collected so far suggest that it is
the remnant of one of the primordial clumps that contributed to the
early assembly of the bulge, a so-called "Bulge Fossil Fragment". Here
we present a new photometric analysis of Terzan 5 based on JWST/NIRCam
observations in the F115W and F200W filters, as well as archival
HST/ACS optical (F606W and F814W) data. The dataset overcomes the
severe and spatially variable extinction along the line of sight and
yields the deepest color-magnitude diagram ever obtained for Terzan 5.
Proper motion selections and high-resolution differential reddening
corrections allow us to isolate bona fide cluster members and to
provide an unprecedented view of the main-sequence turn-off region.
We clearly identify two main components and determine their respective
ages: the old, sub-solar component has an age of 12.5±0.5Gyr,
while the super-solar component is significantly younger, with an age
of 4.7±0.5Gyr. Interestingly, we also find hints of an even
younger main-sequence turn-off and sub-giant branch, consistent with
the presence of a further stellar component with an age of
3.8±0.5Gyr. There is also evidence of a blue plume populated by
stars as bright as m(F115W)∼17.4, suggesting a prolonged period of
star formation extending up to 2.5Gyr ago.
Description:
The table contains star IDs, right ascension and declination,
calibrated magnitudes and relative errors in the HST/ACS F606W and
F814W filters and in the JWST/NIRCam F115W and F200W filters, together
with differential reddening dE(B-V) values.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
terzan5.dat 107 443412 HST+JWST photometric catalog of Terzan 5
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See also:
J/A+A/308/733 : NTT VI photometry in Terzan 5 (Ortolani+ 1996)
J/ApJ/651/1098 : Faint X-ray sources in Terzan 5 (Heinke+, 2006)
J/ApJ/726/L20 : Spectroscopy of Terzan 5 (Origlia+, 2011)
J/ApJ/791/101 : Terzan 5 chemical and kinematical properties (Massari+, 2014)
J/ApJ/795/22 : Iron abundance of Terzan 5 stars (Massari+, 2014)
J/A+A/689/A108 : Terzan 5 variables light curves (Figuera Jaimes+, 2024)
Byte-by-byte Description of file: terzan5.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID Star ID
8- 18 F11.7 deg RAdeg Right ascension (J2000)
20- 30 F11.7 deg DEdeg Declination (J2000)
32- 38 F7.4 mag F606W ?=99.9999 Magnitude in HST/ACS F606W
40- 45 F6.4 mag e_F606W ?=9.9999 Uncertainty on F606W
47- 53 F7.4 mag F814W ?=99.9999 Magnitude in HST/ACS F814W
55- 60 F6.4 mag e_F814W ?=9.9999 Uncertainty on F814W
62- 68 F7.4 mag F115W ?=99.9999 Magnitude in JWST/NIRCam F115W
70- 75 F6.4 mag e_F115W ?=9.9999 Uncertainty on F115W
77- 83 F7.4 mag F200W ?=99.9999 Magnitude in JWST/NIRCam F200W
85- 91 F7.4 mag e_F200W ?=9.9999 Uncertainty on F200W
93- 99 F7.4 mag dE(B-V)VI ?=9.9999 Differential reddening dE(B-V) optical
101-107 F7.4 mag dE(B-V)JK Differential reddening dE(B-V) NIR
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Acknowledgements:
Giorgia Zullo, giorgia.zullo2(at)unibo.it
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 31-Mar-2026