J/ApJ/970/113 AO-assisted BVRI+Ha imaging of NGC330 with SAMI (Navarete+, 2024)
On the Origin of Fast-rotating Stars. I. Photometric calibration and results of
AO-assisted BVRI+Hα imaging of NGC 330 with SAMI/SOAR.
Navarete F., Ticiani Dos Santos P., Carciofi A.C., Figueiredo A.L.
<Astrophys. J., 970, 113 (2024)>
=2024ApJ...970..113N 2024ApJ...970..113N (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Clusters, open ; Stars, Be ;
Photometry, UBVRI ; Photometry, H-alpha
Keywords: Be stars - Magellanic Clouds - Open star clusters
Abstract:
Hα emission is a clear indicator of circumstellar activity in Be
stars, historically employed to assess the classical Be star (CBe)
population in young open clusters (YOCs). The YOC NGC 330 in the Small
Magellanic Cloud exhibits a large known fraction of CBe stars and was
selected for a pilot study to establish a comprehensive methodology
for identifying Hα emitters in the Magellanic Clouds,
encompassing the entire B-type spectral range. Using the SOAR Adaptive
Module Imager (SAMI), we investigated the stellar population of NGC
330 using multiband BVRI+Hα imaging. We identified Hα
emitters within the entire V-band range covered by SAMI/SOAR
observations (V≲22), comprising the complete B-type stellar
population and offering a unique opportunity to explore the Be
phenomenon across all spectral subclasses. The stellar radial
distribution shows a clear bimodal pattern between the most massive
(B5 or earlier) and the lower mass main-sequence objects (later than
B6) within the cluster. The former is concentrated toward the cluster
center (showing a dispersion σ=4.26±0.20pc), whereas the
latter extends across larger radii (σ=10.83±0.65pc),
indicating mass stratification within NGC 330. The total fraction of
emitters is 4.4%±0.5%, notably smaller than previous estimates from
flux- or seeing- limited observations. However, a higher fraction of
Hα emitters is observed among higher mass stars (32.8%±3.4%)
than within lower mass (4.4%±0.9%). Consequently, the putative CBe
population exhibits distinct dynamical characteristics compared to the
bulk of the stellar population in NGC 330. These findings highlight
the significance of the current observations in providing a complete
picture of the CBe population in NGC 330.
Description:
Kron-Cousins BVRI+Hα imaging observations were carried out at
the 4.1m SOAR telescope (Chile) on 2019 January 5.
Table 3 presents the calibrated SAMI photometric results.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 143 10220 Calibrated BVRI+Halpha SAMI Photometry for NGC330
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See also:
J/A+A/472/577 : NGC 330 Be stars and binaries (Martayan+, 2007)
J/A+A/634/A51 : NGC 330 seen by MUSE. I (Bodensteiner+, 2020)
J/A+A/652/A70 : NGC 330 seen by MUSE. II (Bodensteiner+, 2021)
J/A+A/680/A32 : NGC 330 seen by MUSE. III (Bodensteiner+, 2023)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 I5 -- Seq Number the object in the SAMI catalog
7- 18 F12.8 deg RAdeg Right Ascension J2000 (degrees)
20- 31 F12.8 deg DEdeg Declination J2000 (degrees)
33 I1 -- Nfilt Number of filters
35- 40 F6.3 mag Bmag ?=- Apparent magnitude in Kron-Cousins B
filter
42- 47 F6.3 mag e_Bmag ?=- Error on apparent magnitude in B filter
49- 54 F6.3 mag Vmag ?=- Apparent magnitude in Kron-Cousins V
filter
56- 61 F6.3 mag e_Vmag ?=- Error on apparent magnitude in V filter
63- 68 F6.3 mag Rmag ?=- Apparent magnitude in Kron-Cousins R
filter
70- 75 F6.3 mag e_Rmag ?=- Error on apparent magnitude in R filter
77- 82 F6.3 mag Imag ?=- Apparent magnitude in Kron-Cousins I
filter
84- 89 F6.3 mag e_Imag ?=- Error on apparent magnitude in I filter
91- 96 F6.3 mag Hamag ?=- Apparent magnitude in H-alpha filter
98-103 F6.3 mag e_Hamag ?=- Error on apparent magnitude in
H-alpha filter
105-110 F6.3 mag E(B-V) ?=- Total color excess
112-116 I5 K Teff ?=- Effective temperature
118-121 F4.1 [cm/s2] logg ?=- Stellar surface gravity
123-126 F4.1 [--] [Fe/H] ?=- Stellar metallicity
128-131 F4.1 -- alpha ?=- Stellar alpha exponent
133-139 F7.4 mag sigma-mu ?=- Internal mean photometric offset error
141-143 A3 -- Type Photometric classification of the source (1)
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Note (1): Photometric classification as follows:
F = Foreground objects
RGB = evolved (old) stars consistent with >100Myr PARSEC isochrones
MS = Main Sequence stars with no clear H-alpha excess
Ha = Stars with H-alpha excess and selected through Eq. 8
wHa = Stars associated with Ha-R<0 colors, but not selected through Eq. 8
(therefore, weak H-alpha emitters)
SG = bright objects compatible with blue/red super giant stars
(B-I>0 and V<16)
-- = objects associated with incomplete photometry (Nfilt<5) or that did
not fall into any of the previous classification types
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Acknowledgements:
Felipe Navarete, navarete(at)gmail.com
(End) Patricia Vannier [CDS] 29-Aug-2024