J/A+A/641/A142 Post-AGB candidates in LMC and SMC SALT spectra (Szczerba+, 2020)
Validating post-AGB candidates in the LMC and SMC using SALT spectra.
Szczerba R., Hajduk M., Pavlenko, Ya.V., Hrivnak B.J., Kaminsky, B.M.,
Volk K., Siodmiak N. Gezer I., Zacs L., Pych W., Sarna M.
<Astron. Astrophys. 641, A142 (2020)>
=2020A&A...641A.142S 2020A&A...641A.142S (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, giant ; Spectroscopy
Keywords: stars: AGB and post-AGB - stars: abundances - stars: atmospheres -
stars: emission-line, Be
Abstract:
We selected a sample of post-AGB candidates in the Magellanic Clouds
on the basis of their near- and mid-infrared colour characteristics.
Fifteen of the most optically bright post-AGB candidates were observed
with the South African Large Telescope in order to determine their
stellar parameters and thus to validate or discriminate their nature
as post-AGB objects in the Magellanic Clouds. The spectral types of
absorption-line objects were estimated according to the MK
classification, and effective temperatures were obtained by means of
stellar atmosphere modelling. Emission-line objects were classified on
the basis of the fluxes of the emission lines and the presence of the
continuum. Out of 15 observed objects, only 4 appear to be genuine
post-AGB stars (27%). In the SMC, 1 out of 4 is post-AGB, and in the
LMC, 3 out 11 are post-AGB objects. Thus, we can conclude that the
selected region in the colour-colour diagram, while selecting the
genuine post-AGB objects, overlaps severely with other types of
objects, in particular young stellar objects and planetary nebulae.
Additional classification criteria are required to distinguish between
post-AGB stars and other types of objects. In particular, photometry
at far-IR wavelengths would greatly assist in distinguishing young
stellar objects from evolved ones. On the other hand, we showed that
the low-resolution optical spectra appear to be sufficient to
determine whether the candidates are post-AGB objects.
Description:
Spectroscopic data from the South African Large Telescope shown on
Figs. 2, 3 and 4 are available in fig2.dat, fig3.dat and fig4.dat,
respectively. Each spectrum has 2 gaps: in the red setting (Figs.2 and
3) 7130-7200Å and 8170-8220Å, in the blue setting (Fig.4)
3550-3580Å and 3840-3850Å. In the notes to the tables
description we use "the left part" of the spectrum for spectrum before
the first gap, "the middle part" of the spectrum for spectrum between
the two gaps, and "the right part" of the spectrum for spectrum above
the second gap.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 117 16 Designations and positions for the standard star
and post-AGB candidates in the Magellanic Clouds
fig2.dat 220 2995 Red spectra of the objects showing emission lines
or emission and absorption lines
fig3.dat 100 2995 Spectra of the absorption line or featureless
objects in the red setting
fig4.dat 40 2931 Spectra of objects in the blue setting
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- No [0/15] Identification number
4- 22 A19 --- SAGE SAGE name (JHHMMSS.ss+DDMMSS.s)
24- 31 A8 --- SName Short name
32- 48 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
50- 60 A11 --- IRAS IRAS name
63- 78 A16 -- OName Other name
80- 88 F9.6 deg RAdeg Right ascension (J2000) (G1)
90- 99 F10.6 deg DEdeg Declination (J2000) (G1)
101-108 A8 --- FileName1 Name of the file with spectrum
110-117 A8 --- FileName2 Name of the second file with spectrum
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Note (G1): Positions are from the SAGE LMC and SMC surveys for all the sources.
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Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
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3- 10 F8.2 0.1nm lambda1 Wavelength for J004747 flux (1)
13- 20 F8.4 --- RFlux1 Relative flux for J004747 (G1)
23- 30 F8.2 0.1nm lambda2 Wavelength for J004841 flux (1)
33- 40 F8.4 --- RFlux2 Relative flux for J004841 (G1)
43- 50 F8.2 0.1nm lambda4 Wavelength for J011542 flux (1)
53- 60 F8.4 --- RFlux4 Relative flux for J011542 (G1)
63- 70 F8.2 0.1nm lambda5 Wavelength for J045747 flux (1)
73- 80 F8.4 --- RFlux5 Relative flux for J045747 (G1)
83- 90 F8.2 0.1nm lambda6 Wavelength for J045907 flux (1)
93-100 F8.4 --- RFlux6 Relative flux for J045907 (G1)
103-110 F8.2 0.1nm lambda8 Wavelength for J051228 flux (1)
113-120 F8.4 --- RFlux8 Relative flux for J051228 (G1)
123-130 F8.2 0.1nm lambda10 Wavelength for J052229 flux (1)
133-140 F8.4 --- RFlux10 Relative flux for J052229 (G1)
143-150 F8.2 0.1nm lambda12 Wavelength for J052915a flux (1)
153-160 F8.4 --- RFlux12 Relative flux for J052915a (G1)
163-170 F8.2 0.1nm lambda13 Wavelength for J053348 flux (1)
173-180 F8.4 --- RFlux13 Relative flux for J053348 (G1)
183-190 F8.2 0.1nm lambda14 Wavelength for J054055 flux (1)
193-200 F8.4 --- RFlux14 Relative flux for J054055 (G1)
203-210 F8.2 0.1nm lambda15 Wavelength for J055825 flux (1)
213-220 F8.4 --- RFlux15 Relative flux for J055825 (G1)
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Note (1): Records 3-1017 contain the left part of the spectrum,
records 1018-2032 contain the middle part of the spectrum, and
records 2033-2977 contain the right part of the spectrum.
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Byte-by-byte Description of file: fig3.dat
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Bytes Format Units Label Explanations
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3- 10 F8.2 0.1nm lambda0 Wavelength for Sk 105 flux (1)
13- 20 F8.4 --- RFlux0 Relative flux for Sk 105 (G1)
23- 30 F8.2 0.1nm lambda11 Wavelength for J052520 flux (1)
33- 40 F8.4 --- RFlux11 Relative flux for J052520 (G1)
43- 50 F8.2 0.1nm lambda9 Wavelength for J052043 flux (1)
53- 60 F8.4 --- RFlux9 Relative flux for J052043 (G1)
63- 70 F8.2 0.1nm lambda7 Wavelength for J051110 flux (1)
73- 80 F8.4 --- RFlux7 Relative flux for J051110 (G1)
83- 90 F8.2 0.1nm lambda3 Wavelength for J010546 flux (1)
93-100 F8.4 --- RFlux3 Relative flux for J010546 (G1)
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Note (1): Records 3-1017 contain the left part of the spectrum,
records 1018-2032 contain the middle part of the spectrum, and
records 2033-2977 contain the right part of the spectrum.
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Byte-by-byte Description of file: fig4.dat
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Bytes Format Units Label Explanations
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3- 10 F8.2 0.1nm lambda11 Wavelength for J052520 (1)
13- 20 F8.4 --- RFlux11 Relative flux for JJ052520 (G1)
23- 30 F8.2 0.1nm lambda15 Wavelength for J055825 (1)
33- 40 F8.4 --- RFlux15 Relative flux for J055825 (G1)
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Note (1): Records 3-1017 contain the left part of the spectrum,
records 1018-2020 contain the middle part of the spectrum, and
records 2021-2933 contain the right part of the spectrum.
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Global notes:
Note (G1): Spectra were normalised to continuum.
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Acknowledgements:
Ryszard Szczerba, szczerba(at)ncac.torun.pl
(End) Ryszard Szczerba [CAMK, Poland], Patricia Vannier [CDS] 07-Sep-2020