J/A+A/618/A185 VI magnitudes of NGC 4535 stars (Spetsieri+, 2018)
Massive star population of the Virgo Cluster galaxy NGC 4535.
Discovery of new massive variable candidates with the Hubble Space Telescope.
Spetsieri Z.T., Bonanos A.Z., Kourniotis M., Yang M., Lianou S.,
Bellas-Velidis I., Gavras P., Hatzidimitriou D., Kopsacheili M.,
Moretti M.I., Nota A., Pouliasis E., Sokolovsky K.V.
<Astron. Astrophys. 618, A185 (2018)>
=2018A&A...618A.185S 2018A&A...618A.185S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Populations, stellar ; Photometry, HST
Keywords: galaxies: individual: NGC 4535 - stars: massive -
stars: evolution - supergiants - stars: variables: general
Abstract:
We analyzed the massive star population of the Virgo Cluster galaxy
NGC 4535 using archival Hubble Space Telescope Wide Field Planetary
Camera 2 images in filters F555W and F814W, equivalent to Johnson V
and Kron-Cousins I. We performed high precision point spread function
fitting photometry of 24353 sources including 3762 candidate blue
supergiants, 841 candidate yellow supergiants and 370 candidate red
supergiants. We estimated the ratio of blue to red supergiants as a
decreasing function of galactocentric radius. Using Modules for
Experiments in Stellar Astrophysics isochrones at solar metallicity,
we defined the luminosity function and estimated the star formation
history of the galaxy over the last 60Myrs. We conducted 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 120 new variable
candidates with absolute magnitudes ranging from MV=-4 to -11mag. We
used the MESA evolutionary tracks at solar metallicity, to classify
the variables based on their absolute magnitude and their position on
the color-magnitude diagram. Among the new candidate variable sources
are eight candidate variable red supergiants, three candidate variable
yellow supergiants and one candidate luminous blue variable, which we
suggest for follow-up observations.
Description:
We used archival observations of NGC 4535 taken with the HST WFPC2 as
part of the HST Key Project. We used 13 epochs of F555W (equivalent to
Johnson V) and 9 epochs of F814W (equivalent to Kron-Cousins I). The
F555W data consisted in total of eight 3x1200 sec exposures and five
4x1300s exposures, while the F814W of nine 3x1300s exposures.
Objects:
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RA (2000) DE Designation(s)
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12 34 20.31 +08 11 51.9 NGC 4535 = UGC 7727
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 58 24353 Catalog of 24353 stars
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Index [1/24353] Sequnetial number
7 I1 --- Chip [0/3] Chip number (0=PC, 1= WF2, 2=WF3, 3=WF4)
9- 10 I2 h RAh Right ascension (J2000)
12- 13 I2 min RAm Right ascension (J2000)
15- 19 F5.2 s RAs Right ascension (J2000)
21 A1 --- DE- Declination sign (J2000)
22- 23 I2 deg DEd Declination (J2000)
25- 26 I2 arcmin DEm Declination (J2000)
28- 32 F5.2 arcsec DEs Declination (J2000)
34- 39 F6.3 mag Vmag Johnson V magnitude
41- 45 F5.3 mag e_Vmag rms uncertainty on Vmag
47- 52 F6.3 mag Imag Kron-Cousins I magnitude
54- 58 F5.3 mag e_Imag rms uncertainty on Imag
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Acknowledgements:
Zoi-Tzogia Spetsieri, zspetsieri(at)noa.gr
(End) Patricia Vannier [CDS] 09-Aug-2018