J/A+A/629/A3 NGC1326A, 1425 and 4548 supergiants VI mags (Spetsieri+, 2019)
The HST Key Project galaxies NGC 1326A, NGC 1425 and NGC 4548:
New variable stars and massive star population.
Spetsieri Z.T., Bonanos A.Z., Yang M., Kourniotis M., Hatzidimitriou D.
<Astron. Astrophys. 629, A3 (2019)>
=2019A&A...629A...3S 2019A&A...629A...3S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, supergiant ; Stars, variable ;
Photometry, HST
Keywords: galaxies: individual: NGC 1326A - galaxies: individual: NGC 1425 -
galaxies: individual: NGC 4548 - stars: massive -
supergiants - stars: variables: general
Abstract:
Studies on the massive star population in galaxies beyond the Local
Group are the key to understand the link between their numbers and
modes of star formation in different environments. We present the
analysis of the massive star population of the galaxies NGC1326A,
NGC 1425 and NGC 4548 using archival Hubble Space Telescope Wide Field
Planetary Camera 2 images in the F555W and F814W filters. Through high
precision point spread function fitting photometry for all sources in
the three fields we identified 7640 candidate blue supergiants, 2314
candidate yellow supergiants, and 4270 candidate red supergiants. We
provide an estimation the ratio of blue to red supergiants for each
field as a function of galactocentric radius. Using Modules for
Experiments in Stellar Astrophysics (MESA) at solar metallicity, we
defined the luminosity function and estimated the star formation
history of each galaxy. We carried out a variability search in the V
and I filters using three variability indexes: the median absolute
deviation, the interquartile range, and the inverse von-Neumann ratio.
This analysis yielded 243 new variable candidates with absolute
magnitudes ranging from MV=-4 to -10mag. We classified the variable
stars based on their absolute magnitude and their position on the
color-magnitude diagram using the MESA evolutionary tracks at solar
metallicity. Our analysis yielded 8 candidate variable blue
supergiants, 12 candidate variable yellow supergiants, 21 candidate
variable red supergiants, and 4 candidate periodic variables.
Description:
We used archival observations of NGC 1326A, NGC 1425, and NGC 4548
taken with the HST WFPC2 as described in Freedman et al.
(2001ApJ...553...47F 2001ApJ...553...47F) as part of the HST Key Project. For the three
galaxies, we used the observations available in the filters
F555W(equivalent to Johnson V filter) and the F814W (equivalent
toKron-Cousins I). In particular, we used 13 epochs of observations in
F555W and 8 epochs in F814W that are available for the galaxies
NGC 1326A and NGC 4548, while for NGC 1425, we used the 14 available
epochs in F555W and 8 in F814W
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 5897 Catalog of 5897 stars in NGC 1326A
table2.dat 82 5232 Catalog of 5232 stars in NGC 1425
table3.dat 82 5790 Catalog of 5790 stars in NGC 4548
table6.dat 82 48 Properties of the variable candidates in
NGC 1326A ordered by average magnitudes
table7.dat 82 102 Properties of the variable candidates in
NGC 1425 ordered by average magnitudes
table9.dat 82 93 Properties of the variable candidates in
NGC 4548 ordered by average magnitudes
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Byte-by-byte Description of file: table1.dat table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Cluster Cluster name
11- 14 I4 --- ID Sequential number
16 I1 --- Chip [0/4]? Chip number (G1)
18- 19 I2 h RAh Right ascension (J2000)
21- 22 I2 min RAm Right ascension (J2000)
24- 29 F6.3 s RAs Right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Declination (J2000)
35- 36 I2 arcmin DEm Declination (J2000)
38- 42 F5.2 arcsec DEs Declination (J2000)
44- 49 F6.2 pix Xpos X position
51- 56 F6.2 pix Ypos Y position
58- 63 F6.3 mag Vmag V mean magnitude
65- 69 F5.3 mag e_Vmag Mean V magnitude error
71- 76 F6.3 mag Imag I mean magnitude
78- 82 F5.3 mag e_Imag Mean I magnitude error
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Byte-by-byte Description of file: table6.dat table7.dat table9.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Cluster Cluster name
11- 14 A4 --- VID Variable Sequential number, VNNN
16 I1 --- Chip [0/4]? Chip number (G1)
18- 19 I2 h RAh Right ascension (J2000)
21- 22 I2 min RAm Right ascension (J2000)
24- 29 F6.3 s RAs Right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Declination (J2000)
35- 36 I2 arcmin DEm Declination (J2000)
38- 42 F5.2 arcsec DEs Declination (J2000)
44- 49 F6.2 pix Xpos X position
51- 56 F6.2 pix Ypos Y position
58- 63 F6.3 mag Vmag V mean magnitude
65- 69 F5.3 mag e_Vmag Mean V magnitude error
71- 76 F6.3 mag Imag I mean magnitude
78- 82 F5.3 mag e_Imag Mean I magnitude error
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Global notes:
Note (G1): Chip number as follows:
0 = PC
1 = WF2
2 = WF3
3 = WF4
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Acknowledgements:
Zoi-Tzogia Spetsieri, zspetsieri(at)noa.gr
(End) Patricia Vannier [CDS] 05-Aug-2019