J/MNRAS/499/5508 Search for variable subdwarf B stars in TESS I (Sahoo+, 2020)
A search for variable subdwarf B stars in TESS full frame images
I. Variable objects in the southern ecliptic hemisphere.
Sahoo S.K., Baran A.S., Sanjayan S., Ostrowski J.
<Mon. Not. R. Astron. Soc., 499, 5508-5526 (2020)>
=2020MNRAS.499.5508S 2020MNRAS.499.5508S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Binaries, eclipsing ; Stars, subdwarf ;
Stars, B-type ; Spectral types ; Optical
Keywords: stars: binaries: eclipsing -
stars: oscillations (including pulsations) - stars: subdwarfs -
stars: variables: general
Abstract:
We report the results of our search for pulsating subdwarf B stars in
full frame images, sampled at 30 min cadence and collected during Year
1 of the TESS mission. Year 1 covers most of the southern ecliptic
hemisphere. The sample of objects we checked for pulsations was
selected from a subdwarf B stars data base available to public. Only
two positive detections have been achieved, however, as a by-product
of our search we found 1807 variable objects, most of them not
classified, hence their specific variability class cannot be confirmed
at this stage. Our preliminary discoveries include: 2 new subdwarf B
(sdB) pulsators, 26 variables with known sdB spectra, 83
non-classified pulsating stars, 83 eclipsing binaries (detached and
semidetached), a mix of 1535 pulsators and non-eclipsing binaries, two
novae, and 77 variables with known (non-sdB) spectral classification.
Among eclipsing binaries we identified two known HW Vir systems and
four new candidates. The amplitude spectra of the two sdB pulsators
are not rich in modes, but we derive estimates of the modal degree for
one of them. In addition, we selected five sdBV candidates for mode
identification among 83 pulsators and describe our results based on
this preliminary analysis. Further progress will require spectral
classification of the newly discovered variable stars, which hopefully
include more subdwarf B stars.
Description:
We used the sdB data base described by Geier (2020A&A...635A.193G 2020A&A...635A.193G,
Cat. J/A+A/635/A193) that we consider the most updated database of
confirmed sdB as well as sdB candidates. It was prepared based on Gaia
mission (Gaia Collaboration 2020A&A...649A...1G 2020A&A...649A...1G, Cat. I/345) and
several ground-based multiband photometry surveys. Colour indices,
absolute magnitudes and reduced proper motions were used to select the
most suitable candidates. From this sample we selected targets located
in the southern ecliptic hemisphere and covered by TESS silicons.
We used the Eleanor (Feinstein et al. 2019PASP..131i4502F 2019PASP..131i4502F) that is an
open source python framework developed for downloading, analysis, and
visualization of data directly from the TESS FFIs. It is able to
extract corrected time-series data for a given object. As input it
takes the TIC ID, Gaia ID, or coordinates along with observed TESS
sector information, and returns with a table FITS file with
time-series data, optimal aperture shape applied.
We detected significant flux variations in 1807 objects, out of which
28 are classified as sdBs (see Table 1), two novae (see Table 8), 76 as
non-sdBs (see Tables A1-A4), 83 pulsators (see Table 2), 83 non classified
eclipsing binaries (see Tables 3-5) and 1535 spectroscopically unclassified
variables (see Tables 6 and 7).
Finally, we selected five objects out of 83 non-classified pulsators to
identify their pulsation geometry by assuming them as g-mode rich sdBVs
(see Tables 9-13).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 136 28 Basic information of 28 objects classified as
sdBs
table2.dat 88 83 Basic information of 83 pulsator candidates we
found that are not spectroscopically classified
table3.dat 137 32 Basic information of 32 eclipsing binaries that
show both primary and secondary eclipses
table4.dat 126 42 Basic information of 42 eclipsing binaries that
show primary eclipses only
table5.dat 107 9 Basic information of nine eclipsing binaries
with eccentric orbits
table6.dat 159 273 Basic information of 273 spectroscopically
unclassified variables
table7.dat 139 1262 Basic information of 1262 spectroscopically
unclassified variables
table8.dat 59 2 Basic information of two nova stars
tablea1.dat 111 11 Basic information of 11 spectroscopically
classified eclipsing binaries
tablea2.dat 81 36 Basic information of 36 spectroscopically
classified variables
tablea3.dat 102 15 Basic information of 15 spectroscopically
classified variables
tablea4.dat 111 14 Basic information of 14 spectroscopically
classified pulsators
table9.dat 55 19 List of frequencies detected in
Gaia DR2 5233348350879239680
table10.dat 54 14 List of frequencies detected in
Gaia DR2 5250674622612902912
table11.dat 54 18 List of frequencies detected in
Gaia DR2 5365175740610237568
table12.dat 54 13 List of frequencies detected in
Gaia DR2 5391470732981138816
table13.dat 54 7 List of frequencies detected in
Gaia DR2 6096794282417069696
--------------------------------------------------------------------------------
See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 55 A24 --- Name Object name
57- 63 F7.4 mag Gmag Gaia DR2 G-band magnitude
65- 67 A3 --- Sector Sector
69- 77 A9 d Period Period
79-136 A58 --- Remarks Remarks
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 38 F7.4 mag Gmag Gaia DR2 G-band magnitude
40- 44 A5 --- Sector Sector
46- 88 A43 --- Remarks Remarks
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 38 F7.4 mag Gmag Gaia DR2 G-band magnitude
40- 50 A11 --- Sector Sector
52- 57 F6.4 d Period Period
59-137 A79 --- Remarks Remarks
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 38 F7.4 mag Gmag Gaia DR2 G-band magnitude
40- 54 A15 --- Sector Sector
56- 61 F6.4 d Period Period
63-126 A64 --- Remarks Remarks
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 38 F7.4 mag Gmag Gaia DR2 G-band magnitude
40- 44 A5 --- Sector Sector
46- 52 F7.4 d Period ? Period
54-107 A54 --- Remarks Remarks
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 38 F7.4 mag Gmag Gaia DR2 G-band magnitude
40- 54 A15 --- Sector Sector
56- 61 F6.4 d Period Period
63- 64 A2 --- Max Flag indicated the number of maxima (1)
66-159 A94 --- Remarks Remarks
--------------------------------------------------------------------------------
Note (1): Flag as follows:
1s = Object that shows one symmetric maximum (43/273)
1a = Object that shows one asymmetric maximum (178/273)
2m = Object that shows two maxima (52/273)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 38 F7.4 mag Gmag Gaia DR2 G-band magnitude
40- 53 A14 --- Sector Sector
55-139 A85 --- Remarks Remarks
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 29 I9 --- TIC TESS Input Catalog identifier
31- 36 A6 --- Name Object name
38- 39 A2 --- SpType Spectral type
41- 47 F7.4 mag Gmag Gaia DR2 G-band magnitude
49- 59 A11 --- Sector Sector
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 40 A9 --- SpType Spectral type
42- 48 F7.4 mag Gmag Gaia DR2 G-band magnitude
50- 53 A4 --- Sector Sector
55- 61 F7.4 d Period Period
63- 65 A3 --- Type Eclipsing binary type (1)
67-111 A45 --- Remarks Remarks
--------------------------------------------------------------------------------
Note (1): Type as follows:
pse = Primary and secondary eclipses (7/11)
pe = Primary eclipse only (2/11)
eo = Eccentric orbit (2/11)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 38 A7 --- SpType Spectral type
40- 46 F7.4 mag Gmag Gaia DR2 G-band magnitude
48- 52 A5 --- Sector Sector
54- 81 A28 --- Remarks Remarks
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 30 I10 --- TIC TESS Input Catalog identifier
32- 41 A10 --- SpType Spectral type
43- 49 F7.4 mag Gmag Gaia DR2 G-band magnitude
51- 56 A6 --- Sector Sector
58- 63 F6.4 d Period Period
65- 66 A2 --- Max Flag indicated the number of maxima (1)
68-102 A35 --- Remarks Remarks
--------------------------------------------------------------------------------
Note (1): Flag as follows:
1s = Object that shows one symmetric maximum (11/15)
1a = Object that shows one asymmetric maximum (1/15)
2m = Object that shows two maxima (3/15)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 29 I9 --- TIC TESS Input Catalog identifier
31- 38 A8 --- SpType Spectral type
40- 46 F7.4 mag Gmag Gaia DR2 G-band magnitude
48- 50 A3 --- Sector Sector
52-111 A60 --- Remarks Remarks
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table9.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- fID Frequency identifier
5- 11 F7.3 uHz Freq Frequency value in µHz
13- 17 F5.3 uHz e_Freq Error on Freq
19- 26 F8.2 s Period Period
28- 31 F4.2 s e_Period Error on Period
33- 37 F5.3 10-3 Amp Amplitude
39- 42 F4.2 10-3 e_Amp Error on Amp
44- 47 F4.1 --- S/N Signal to noise ratio
49 I1 --- l ? Mode of degree
51- 52 I2 --- m ? Azimuthal order
54- 55 I2 --- n ? Radial order
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1[0123].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- fID Frequency identifier
5- 11 F7.3 uHz Freq Frequency value in µHz
13- 17 F5.3 uHz e_Freq Error on Freq
19- 26 F8.2 s Period Period
28- 32 F5.2 s e_Period Error on Period
34- 38 F5.3 10-3 Amp Amplitude
40- 44 F5.3 10-3 e_Amp Error on Amp
46- 49 F4.1 --- S/N Signal to noise ratio
51 I1 --- l ? Mode of degree
53- 54 A2 --- n ? Radial order
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Baran et al., Paper II 2021MNRAS.503.3828B 2021MNRAS.503.3828B
Sahoo et al., Paper III 2023MNRAS.519.2486S 2023MNRAS.519.2486S
(End) Ana Fiallos [CDS] 12-Sep-2023