J/MNRAS/487/4695 Rotationally variable A stars from TESS (Sikora+, 2019)
MOBSTER - II. Identification of rotationally variable A stars observed with
TESS in sectors 1-4.
Sikora J., David-Uraz A., Chowdhury S., Bowman D.M., Wade G.A., Khalack V.,
Kobzar O., Kochukhov O., Neiner C., Paunzen E.
<Mon. Not. R. Astron. Soc., 487, 4695-4710 (2019)>
=2019MNRAS.487.4695S 2019MNRAS.487.4695S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Stars, variable ; Optical ;
Stars, A-type ; Stars, Am ; Stars, Ap
Keywords: stars: early-type - stars: magnetic field - stars: rotation
Abstract:
Recently, high-precision optical 2-min cadence light curves obtained
with TESS for targets located in the mission's defined first four
sectors have been released. The majority of these high-cadence and
high-precision measurements currently span ∼28d, thereby allowing
periodic variability occurring on time-scales~<14d to potentially be
detected. Magnetic chemically peculiar (mCP) A-type stars are well
known to exhibit rotationally modulated photometric variability that
is produced by inhomogeneous chemical abundance distributions in their
atmospheres. While mCP stars typically exhibit rotation periods that
are significantly longer than those of non-mCP stars, both populations
exhibit typical periods ~<10d; therefore, the early TESS releases are
suitable for searching for rotational modulation of the light curves
of both mCP and non-mCP stars. We present the results of our search
for A-type stars that exhibit variability in their TESS light curves
that is consistent with rotational modulation based on the first two
data releases obtained from sectors 1 to 4. Our search yielded 134
high-probability candidate rotational variables - 60 of which have not
been previously reported. Approximately half of these stars are
identified in the literature as Ap (mCP) stars. Comparisons between
the subsample of high-probability candidate rotationally variable Ap
stars and the subsample of stars that are not identified as Ap reveal
that the latter subsample exhibits statistically (i) shorter rotation
periods and (ii) significantly lower photometric amplitudes.
Description:
TESS is optimized to detect planetary transit signatures in light
curves of MS dwarf stars having IC magnitudes of approximately 4-13
(Ricker et al. 2015JATIS...1a4003R 2015JATIS...1a4003R). The passband of the filter used
by the onboard photometer has an effective wavelength of ∼7500Å and
a width of ∼4000Å (Sullivan et al. 2015ApJ...809...77S 2015ApJ...809...77S, Cat.
J/ApJ/809/77). In this study, we used the 2-min PDC_SAP light curves
processed by the TESS Science Team and available at the Mikulski
Archive for Space Telescopes (MAST) (https://archive.stsci.edu/tess/).
We refer the reader to Jenkins et al. (2016SPIE.9913E..3EJ) for a
description of the pipeline that produces these light curves.
The TESS data considered in this study consist of targets located in
sectors 1-4. These sectors are in the southern ecliptic and contain
targets with right ascension (RA) values of RA<131° and
RA>308° and declination (Dec) values of -85<Dec<+12°. The
observations have been obtained over a period of ∼4months from July 25
to November 14, 2018.
We have identified 134 high-probability candidate rotational variable
stars based on 2-min cadence TESS light curves among a sample of 1962
A-type stars. More than half of these 134 stars (76 of 134) are
identified in the literature as Ap stars, which are expected to
exhibit photometric rotational modulation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 148 134 Parameters associated with the 134 identified
high-probability candidate rotational variables
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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- 9 I9 --- ID TIC identifier
11- 26 A16 --- Name Star name
28- 40 A13 --- SpType Spectral type
42- 45 F4.1 mag Vmag V-band magnitude
47- 52 F6.3 mmag DTmax Maximum photometric amplitude associated with
the rotational modulation signal
54- 58 F5.3 mmag e_DTmax Error on DTmax
60 I1 --- f_DTmax Flag on DTmax (1)
62- 70 F9.6 d Prot Rotation period inferred from the TESS light
curve
72- 79 F8.6 d e_Prot Error on Prot
81- 89 F9.6 d Protp1 ? Published rotation period
91- 98 F8.6 d e_Protp1 ? Error on Protp1
100 A1 --- r_Protp1 Reference for Protp1 (2)
102-110 F9.6 d Protp2 ? Other published rotation period
112-119 F8.6 d e_Protp2 ? Error on Protp2
121 A1 --- r_Protp2 Reference for Protp2 (2)
123-139 A17 --- Type Star type (3)
141 I1 --- f_Type ? Flag on Type (4)
143 A1 --- r_Type Reference for Type (2)
145-146 A2 --- Magdet Confidence with which any reported magnetic
field measurements in the literature have
been obtained (5)
148 A1 --- r_Magdet Reference for Magdet (2)
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Note (1): Flag as follows:
1 = ΔTmax corresponds to the rotation frequency (f1)
2 = ΔTmax corresponds to the first harmonic frequency (f_2)
Note (2): References as follows:
a = Catalano, Leone & Kroll (1998A&AS..129..463C 1998A&AS..129..463C)
b = Cunha et al. 2019 (submitted)
c = Pourbaix et al. (2004A&A...424..727P 2004A&A...424..727P, Cat. V/122)
d = Bagnulo et al. (2015A&A...583A.115B 2015A&A...583A.115B, Cat. J/A+A/583/A115)
e = Netopil et al. (2017MNRAS.468.2745N 2017MNRAS.468.2745N, Cat. J/MNRAS/468/2745)
f = Kudryavtsev et al. (2006MNRAS.372.1804K 2006MNRAS.372.1804K, Cat. J/MNRAS/372/1804)
g = Oelkers et al. (2018AJ....155...39O 2018AJ....155...39O, Cat. J/AJ/155/39)
h = Borra & Landstreet (1980ApJS...42..421B 1980ApJS...42..421B)
i = Malkov et al. (2012A&A...546A..69M 2012A&A...546A..69M, Cat. J/A+A/546/A69)
j = Sikora et al. (2019MNRAS.483.3127S 2019MNRAS.483.3127S, Cat. J/MNRAS/483/3127)
k = Kurtz (1984)
l = Bohlender, Landstreet & Thompson (1993A&A...269..355B 1993A&A...269..355B)
m = Martinez & Kurtz (1990MNRAS.246..699M 1990MNRAS.246..699M)
n = Mathys et al. (1997A&AS..124..475M 1997A&AS..124..475M)
o = Borra & Landstreet (1975PASP...87..961B 1975PASP...87..961B)
p = Maitzen, Weiss & Wood (1980A&A....81..323M 1980A&A....81..323M)
q = Auriere et al. (2007A&A...475.1053A 2007A&A...475.1053A, Cat. J/A+A/475/1053)
r = Kurtz & Kreidl (1985MNRAS.216..987K 1985MNRAS.216..987K)
s = Kurtz, van Wyk & Marang (1990MNRAS.243..289K 1990MNRAS.243..289K)
t = Manfroid & Renson (1983IBVS.2311....1M 1983IBVS.2311....1M)
Note (3): Type as follows:
SB = spectroscopic binary
VB = visual binary
delta Scuti = δ Scuti pulsator
roAp = rapidly-oscillating Ap star
AMod = The amplitude of the rotational modulation is found to vary
over time
Note (4): Flag as follows:
1 = Porb=5.400945(40)d
2 = Porb=464.66yr
Note (5): Confidence as follows:
DD = definite detection
MD = marginal detection
ND = null detection
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History:
From electronic version of the journal
References:
David-Uraz et al. Paper I 2019MNRAS.487..304D 2019MNRAS.487..304D
(End) Ana Fiallos [CDS] 18-Nov-2022