J/A+A/660/A70 Long-period Ap stars discovered with TESS data (Mathys+, 2022)
Long-period Ap stars discovered with TESS data:
The northern ecliptic hemisphere.
Mathys G., Kurtz D.W., Holdsworth D.L.
<Astron. Astrophys., 660, A70 (2022)>
=2022A&A...660A..70M 2022A&A...660A..70M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Stars, peculiar ; Magnetic fields
Keywords: stars: chemically peculiar - stars: magnetic field -
stars: rotation - stars: oscillations
Abstract:
The rotation periods of the magnetic Ap stars span five to six orders
of magnitude. While it is well established that period differentiation
must have taken place at the pre-main sequence stage, the physical
processes that lead to it remain elusive. The existence of Ap stars
that have rotation periods of tens to hundreds of years is
particularly intriguing, and their study represents a promising avenue
to gain additional insight into the origin and evolution of rotation
in Ap stars. Historically, almost all the longest period Ap stars
known have been found to be strongly magnetic; very few weakly
magnetic Ap stars with very long periods have been identified and
studied. To remedy that, we showed how a systematic search based on
the analysis of TESS photometric data could be performed to identify
super-slowly rotating Ap (ssrAp) stars independently of the strengths
of their magnetic fields, with the intention to characterise the
distribution of the longest Ap star rotation periods in an unbiased
manner. We successfully applied this method to the analysis of the
TESS 2-min cadence observations of Ap stars of the southern ecliptic
hemisphere. For our present study, we applied the same approach to the
analysis of the TESS 2-min cadence observations of Ap stars of the
northern ecliptic hemisphere. We confirm that the technique leads to
the reliable identification of ssrAp star candidates in an unbiased
manner. We find 67 Ap stars with no rotational variability in the
northern ecliptic hemisphere TESS data. Among them, 46 are newly
identified ssrAp star candidates, which is double the number found in
the southern ecliptic hemisphere. We confirm that super-slow rotation
tends to occur less frequently in weakly magnetic Ap stars than in
strongly magnetic stars. We present new evidence of the existence of a
gap between ∼2 kG and ∼3 kG in the distribution of the magnetic field
strengths of long period Ap stars. We also confirm that the incidence
of roAp stars is higher than average in slowly rotating Ap stars. We
report the unexpected discovery of nine definite and five candidate
δ Sct stars, and of two eclipsing binaries. This work paves the
way for a systematic, unbiased study of the longest period Ap stars,
with a view to characterise the correlations between their rotational,
magnetic, and pulsational properties.
Description:
Table A.1 lists the 67 long rotation Ap star candidates that were
identified.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 152 67 *List of long-period Ap stars found by our
technique in the TESS Sectors 14-26 data
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Note on tablea1.dat: obtained in the second year of mission operations and
covering the northern ecliptic hemisphere.
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See also:
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- TIC TIC number
11- 25 A15 --- OName Other name
27- 36 A10 --- SpType Spectral type
38 A1 --- n_SpType [d] Note on SpType (1)
41- 46 F6.3 mag Vmag V magnitude
47 A1 --- n_Vmag [b] b for V magnitude from Zacharias et al.
(2004, Cat. I/297)
49- 53 I5 K Teff ? Effective temperature
55- 57 F3.1 [cm/s2] logg ? Surface gravity
59- 63 A5 --- roAp roAp flag
65- 67 F3.1 kG <Bz>rms ? Root-mean-square longitudinal field
68 A1 --- --- [/]
69- 71 F3.1 kG B0 ? Average value over a rotation cycle of the
mean magnetic field modulus
72 A1 --- --- [/]
73- 76 F4.1 kG Q0 ? Average value over a rotation cycle of the
mean quadratic magnetic field <Bq>
78- 80 A3 --- r_B0 References for magnetic field (3)
82- 89 F8.3 d Prot ? Rotational period
91 A1 --- n_Prot [ce] Note on Prot (1)
92 A1 --- u_Prot [?] Uncertainty flag on Prot
94- 95 I2 --- r_Prot ? References for rotational period (3)
98-101 A4 --- Lines Lines (2)
102 A1 --- l_vsini Limit flag on vsini
103-107 F5.1 km/s vsini ? Rotational velocity
110-113 A4 --- r_vsini References for rotational velocity (3)
115-139 A25 --- Notes Notes
141-152 A12 ---- Sectors TESS sectors
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Note (1): Notes as follows:
d = SB2 system; HD 174017 (secondary) is the Ap component (A0p SrCrEu);
HD 174016 is a G6III star (Renson & Manfroid, 2009A&A...498..961R 2009A&A...498..961R,
Cat. III/260), unresolved by speckle interferometry (Hartkopf &
McAlister, 1984PASP...96..105H 1984PASP...96..105H; Horch et al. 2015AJ....150..151H 2015AJ....150..151H,
Cat. J/AJ/150/151).
c = TESS photometry definitely does not show any low-frequency variability;
the published period may be spurious.
e = TESS photometry shows variations with a period of 5.21d, which is typical
of rotation, but the amplitude is very low and the period is not
an alias of the published value.
Note (2): Lines as follows:
r = resolved
s = sharp
(s) = rather sharp
Note (3): References as follows:
1 = Mathys (2017A&A...601A..14M 2017A&A...601A..14M, Cat. J/A+A/601/A14)
2 = Balona et al. (2011MNRAS.410..517B 2011MNRAS.410..517B)
3 = this paper
4 = Kudryavtsev & Romanyuk (2012AN....333...41K 2012AN....333...41K)
5 = Romanyuk et al. (2017AstBu..72..391R 2017AstBu..72..391R, Cat. J/other/AstBu/72.391)
6 = Romanyuk et al. (2018AstBu..73..178R 2018AstBu..73..178R, cat. J/other/AstBu/73.178)
7 = Balona et al. (2011MNRAS.410..517B 2011MNRAS.410..517B)
8 = Babcock (1958ApJS....3..141B 1958ApJS....3..141B)
9 = Preston (1971ApJ...164..309P 1971ApJ...164..309P)
10 = Ziznovsky & Romanyuk (1990BAICz..41..118Z 1990BAICz..41..118Z)
11 = Auriere et al. (2007A&A...475.1053A 2007A&A...475.1053A, Cat. J/A+A/475/1053)
12 = Mathys et al. (1997A&AS..123..353M 1997A&AS..123..353M, Cat. J/A+AS/123/353)
13 = Hey et al. (2019MNRAS.488...18H 2019MNRAS.488...18H)
14 = Adelman (1981A&AS...44..265A 1981A&AS...44..265A)
15 = Pyper & Adelman (2017PASP..129j4203P 2017PASP..129j4203P)
16 = Mathys et al. (2016A&A...586A..85M 2016A&A...586A..85M, Cat. J/A+A/586/A85)
17 = Huemmerich et al. (2016AJ....152..104H 2016AJ....152..104H, Cat. J/AJ/152/104)
18 = Netopil et al. (2017MNRAS.468.2745N 2017MNRAS.468.2745N, Cat. J/MNRAS/468/2745)
19 = Wraight et al. (2012MNRAS.420..757W 2012MNRAS.420..757W, Cat. J/MNRAS/420/757)
20 = Wade et al. (2000A&A...355.1080W 2000A&A...355.1080W)
21 = Zorec & Royer (2012A&A...537A.120Z 2012A&A...537A.120Z, Cat. J/A+A/537/A120)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 22-Aug-2022