J/A+A/690/A371 NGC 6121 and NGC 6397 JWST/NIRISS data (Libralato+, 2024)
JWST imaging of the closest globular clusters. IV. Chemistry, luminosity and
mass functions of the lowest-mass members in the NIRISS parallel fields.
Libralato M., Gerasimov R., Bedin L., Anderson J., Apai D., Bellini A.,
Burgasser A. J., Griggio M., Nardiello D., Salaris M., Scalco M.,
Vesperini E.
<Astron. Astrophys. 690, A371 (2024)>
=2024A&A...690A.371L 2024A&A...690A.371L (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Photometry, infrared ; Optical
Keywords: techniques: photometric - astrometry - photometry - proper motions -
globular clusters: individual: NGC 6121 -
globular clusters: individual: NGC 6397
Abstract:
We present observations of the two closest globular clusters, NGC 6121
and NGC 6397, taken with the NIRISS detector of JWST. The combination
of our new JWST data with archival Hubble Space Telescope (HST) images
allows us to compute proper motions, disentangle cluster members from
field objects, and probe the main sequence (MS) of the clusters down
to <0.1M☉ as well as the brighter part of the white-dwarf
sequence. We show that theoretical isochrones fall short in modeling
the low-mass MS and discuss possible explanations of the observed
discrepancies. Our analysis suggests that the lowest-mass members of
both clusters are significantly more metal-rich and oxygen-poor than
their higher-mass counterparts. It is unclear if the difference is
caused by a genuine mass-dependent chemical heterogeneity,
low-temperature atmospheric processes altering the observed
abundances, or systematic shortcomings in the models. We computed the
present-day local luminosity and mass functions of the two clusters;
our data reveal a strong flattening of the mass function indicative of
a significant preferential loss of low-mass stars in agreement with
previous dynamical models for these two clusters. We made our NIRISS
astro-photometric catalogs and stacked images publicly available to
the community.
Description:
Astro-photometric catalogs and stakced images of NGC 6121 and
NGC 6397. Caveats about the catalogs and their usage can be found in
Appendix C of the paper.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
ngc6121.dat 279 12270 NGC 6121 astro-photometric catalog
ngc6397.dat 203 11566 NGC 6397 astro-photometric catalog
list.dat 128 3 List of fits images
fits/* . 3 Individual fits images
--------------------------------------------------------------------------------
See also:
J/A+A/490/625 : Abundances of NGC 6121 red giants (Marino+, 2008)
J/A+A/594/A79 : NGC 6121 turnoff and subgiant stars abundances (Spite+, 2016)
J/A+A/490/777 : Abundances of Population II stars in NGC 6397 (Lind+, 2008)
J/A+A/503/545 : Equivalent widths of Li, Na, Fe, Ca in NGC 6397 (Lind+, 2009)
J/A+A/588/A148 : NGC 6397 stars MUSE spectra (Husser+, 2016)
J/A+A/635/A161 : NGC6397 stars measured atmospheric parameters (Jain+, 2020)
Byte-by-byte Description of file: ngc6121.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.10 deg RAdeg Right Ascension (ICRS) at Ep=2023
16- 29 F14.10 deg DEdeg Declination (ICRS) at Ep=2023
31- 39 F9.4 pix Xpos X master-frame position (40mas/pixel)
41- 50 F10.4 pix Ypos Y master-frame position (40mas/pixel)
52- 56 I5 --- Name ID number of the source
58- 64 F7.4 mag F150Wmagc Calibrated JWST/NIRISS F150W magnitude
66- 72 F7.4 mag F606Wmagc ?=0 Calibrated JWST/ACS/WFC F606W magnitude
74- 80 F7.4 mag F814Wmagc ?=0 Calibrated JWST/ACS/WFC F814W magnitude
82 I1 --- Fieldflag [1/2] Field flag (G1)
84 I1 --- Membership [0/1] Membership flag (1)
86 I1 --- satF150W [0/9] F150W saturation flag (G2)
88- 95 F8.4 mag F150Wmag F150W instrumental magnitude
97-103 F7.4 mag e_F150Wmag ?=0 F150W magnitude rms
105-109 F5.3 --- qF150W ?=0 F150W quality-of-PSF-fit parameter
111-119 F9.4 --- oF150W ?=0 F150W fractional flux due to neighbors
within the fitting radius prior to
neighbor subtraction
121-122 I2 --- fF150W ?=0 Number of individual F150W exposures in
which an object was found
124-125 I2 --- gF150W ?=0 Number of individual F150W exposures
used to measure an object
127-134 F8.4 --- rxsF150W ?=0 F150W excess/deficiency of flux outside
the fitting radius (RADXS)
136-142 F7.2 --- skyF150W ?=0 F150W sky in DN
144-150 F7.2 --- rmsskyF150W ?=0 F150W sky rms in DN
152 I1 --- satF606W [0/9] F606W saturation flag (G2)
154-161 F8.4 mag F606Wmag ?=0 F606W instrumental magnitude
163-169 F7.4 mag e_F606Wmag ?=0 F606W magnitude rms
171-175 F5.3 --- qF606W ?=0 F606W quality-of-PSF-fit parameter
177-183 F7.4 --- oF606W ?=0 F606W fractional flux due to neighbors
within the fitting radius prior to
neighbor subtraction
185-186 I2 --- fF606W ?=0 Number of individual F606W exposures in
which an object was found
188-189 I2 --- gF606W ?=0 Number of individual F606W exposures
used to measure an object
191-198 F8.4 --- rxsF606W ?=0 F606W excess/deficiency of flux outside
the fitting radius (RADXS)
200-206 F7.2 --- skyF606W ?=0 F606W sky in electrons
208-214 F7.2 --- rmsskyF606W ?=0 F606W sky in electrons
216 I1 --- satF814W [0/9] F814W saturation flag (G2)
218-225 F8.4 --- F814Wmag ?=0 F814W instrumental magnitude
227-233 F7.4 --- e_F814Wmag ?=0 F814W magnitude rms
235-239 F5.3 --- qF814W ?=0 F814W quality-of-PSF-fit parameter
241-248 F8.4 --- oF814W ?=0 F814W fractional flux due to neighbors
within the fitting radius prior to
neighbor subtraction
250-251 I2 --- fF814W ?=0 Number of individual F814W exposures in
which an object was found
253-254 I2 --- gF814W ?=0 Number of individual F814W exposures
used to measure an object
256-263 F8.4 --- rxsF814W ?=0 F814W excess/deficiency of flux outside
the fitting radius (RADXS)
265-271 F7.2 --- skyF814W ?=0 F814W sky in electrons
273-279 F7.2 --- rmsskyF814W ?=0 F814W sky in electrons
--------------------------------------------------------------------------------
Note (1): Membership flag as follows:
1 = Cluster stars
0 = all other objects
--------------------------------------------------------------------------------
Byte-by-byte Description of file: ngc6397.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.10 deg RAdeg Right Ascension (ICRS) at Ep=2023
16- 29 F14.10 deg DEdeg Declination (ICRS) at Ep=2023
31- 39 F9.4 pix Xpos X master-frame position (40mas/pixel)
41- 49 F9.4 pix Ypos Y master-frame position (40mas/pixel)
51- 55 I5 --- Name ID number of the source
57- 63 F7.4 mag F150Wmagc Calibrated JWST/NIRISS F150W magnitude
65- 71 F7.4 mag F775Wmagc Calibrated JWST/ACS/WFC F775W magnitude
73 I1 --- Membership [0/1] Membership flag (G1)
75 I1 --- satF150W [0/9] F150W saturation flag (G2)
77- 84 F8.4 mag F150Wmag ?=0 F150W instrumental magnitude
86- 92 F7.4 mag e_F150Wmag ?=0 F150W magnitude rms
94- 98 F5.3 --- qF150W ?=0 F150W quality-of-PSF-fit parameter
100-109 F10.4 --- oF150W ?=0 F150W fractional flux due to neighbors
within the fitting radius prior to
neighbor subtraction
111-112 I2 --- fF150W ?=0 Number of individual F150W exposures in
which an object was found
114-115 I2 --- gF150W ?=0 Number of individual F150W exposures
used to measure an object
117-124 F8.4 --- rxsF150W ?=0 F150W excess/deficiency of flux outside
the fitting radius (RADXS)
126-132 F7.2 --- skyF150W ?=0 F150W sky in DN
134-140 F7.2 --- rmsskyF150W ?=0 F150W sky rms in DN
142 I1 --- satF775W [0/9] F775W saturation flag (G2)
144-151 F8.4 mag F775Wmag ?=0 F775W instrumental magnitude
153-159 F7.4 mag e_F775Wmag ?=0 F775W magnitude rms
161-165 F5.3 --- qF775W ?=0 F775W quality-of-PSF-fit parameter
167-174 F8.4 --- oF775W ?=0 F775W fractional flux due to neighbors
within the fitting radius prior to
neighbor subtraction
176 I1 --- fF775W ?=0 Number of individual F775W exposures in
which an object was found
178 I1 --- gF775W ?=0 Number of individual F775W exposures
used to measure an object
180-187 F8.4 --- rxsF775W ?=0 F775W excess/deficiency of flux outside
the fitting radius (RADXS)
189-195 F7.2 --- skyF775W ?=0 F775W sky in electrons
197-203 F7.2 --- rmsskyF775W ?=0 F775W sky rms in electrons
--------------------------------------------------------------------------------
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 F4.2 arcsec/pix scale Scale of the image
25- 28 I4 --- Nx Number of pixels along X-axis
30- 34 I5 --- Ny Number of pixels along Y-axis
36- 41 I6 Kibyte size Size of FITS file
43- 80 A38 --- FileName Name of FITS file, in subdirectory fits
82-128 A47 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Global notes:
Note (G1): Flag as follows:
1 = JWST/NIRISS Northern field
2 = JWST/NIRISS Southern field
Note (G2): Saturated stars have a saturation flag set to 9. If multiple exposure
times are present in the data set, the saturation flag is 0 for a
measurement obtained from the longest exposure(s), and progressively
increases (by 1) with decreasing exposure time of the image(s) from
which it was measured.
--------------------------------------------------------------------------------
Acknowledgements:
Mattia Libralato, mattia.libralato(at)inaf.it
(End) Patricia Vannier [CDS] 09-Sep-2024