J/MNRAS/490/2112 Rotational frequencies in A and B stars (Balona, 2019)
Evidence for spots on hot stars suggests major revision of stellar physics.
Balona L.A.
<Mon. Not. R. Astron. Soc., 490, 2112-2116 (2019)>
=2019MNRAS.490.2112B 2019MNRAS.490.2112B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, A-type ; Stars, B-type ; Stars, early-type ;
Stars, variable ; Rotational velocities ; Spectral types ;
Effective temperatures ; Optical
Keywords: stars: early-type - stars: rotation - starspots
Abstract:
It has long been thought that starspots are not present in the A and B
stars because magnetic fields cannot be generated in stars with
radiative envelopes. Space observations show that a considerable
fraction of these stars varies in light with periods consistent with
the expected rotation periods. Here we show that the photometric
periods are the same as the rotation periods and that starspots are
the likely cause for the light variations. This discovery has
wide-ranging implications and suggests that a major revision of the
physics of hot stellar envelopes may be required.
Description:
The data used in this study comprise light curves from the full
four-year Kepler mission, from the K2 mission and from sectors 1-13 of
the TESS mission. Corrected data using pre-search data conditioning
(PDC) were used for Kepler and TESS. For K2 data, light curves
corrected by the method described in Vanderburg & Johnson
(2014PASP..126..948V 2014PASP..126..948V) were used.
Each star was assigned, where appropriate, a variability type by
visual inspection of the periodogram and light curve with the
assistance of the spectral type or effective temperature. As far as
possible, the classification scheme used in the General Catalogue of
Variable Stars (Samus et al. 2009yCat....102025S 2009yCat....102025S, Cat. B/gcvs) was
followed.
The advent of the TESS mission has greatly increased the number of
stars with effective temperatures greater than 7000K. There are now
2861 of these stars with known photometric periods. This allows a more
rigorous test of the rotational modulation hypothesis than is possible
using only Kepler and K2 data. A catalogue of the rotation
frequencies, amplitudes, and other information is available in Table 1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 123 2861 Catalogue of rotational frequencies
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See also:
B/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name KIC, EPIC or TIC number
16- 29 A14 --- VarType Variability class (1)
31- 36 F6.3 mag Vmag V-band magnitude
38- 42 I5 K Teff Effective temperature (2)
44- 47 F4.2 [Lsun] logL Logarithm of the star luminosity (3)
49- 53 F5.1 km/s vsini ? Projected rotational velocity (4)
55- 62 F8.6 ct/d nurot Rotation frequency
64- 71 F8.6 ct/d e_nurot Error on nurot
73- 78 F6.3 10-3 A1 Amplitude of fundamental frequency (in parts
per thousand)
80- 84 F5.3 10-3 e_A1 Error on A1
86- 91 F6.3 10-3 A2 Amplitude of first harmonic (in parts per
thousand)
93- 97 F5.3 10-3 e_A2 Error on A2
99-103 F5.1 --- S/N Signal-to-noise of fundamental
105-123 A19 --- SpType Spectral type (5)
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Note (1): All stars are classified as ROT (rotational variable), but many
include additional classes. BCEP - beta Cephei; DSCT - delta Scuti;
GDOR - gamma Doradus; MAIA - delta Scuti star hotter than the blue
edge; SPB - Slowly pulsating B star; FLARE - suspected flare;
ROTD - additional broad feature at slightly lower frequency than the
rotation peak. ROT+ROT indicates two pairs of fundamental plus first
harmonic peaks which is interpreted as two stars, each with
rotational modulation.
Note (2): The effective temperatures for A stars observed by Kepler are those
from the Kepler Input Catalogue incremented by 144K (Balona et al.
2015MNRAS.452.3073B 2015MNRAS.452.3073B). For TESS stars the effective temperatures are
from the TESS input catalogue. For K2 and B stars, values from the
literature are used.
Note (3): The value of log(L/L☉) is determined from the GAIA DR2 parallax
and bolometric corrections from Pecaut et al. (2013ApJS..208....9P 2013ApJS..208....9P)
using a 3D map of interstellar extinction by Gontcharov
(2017AstL...43..472G 2017AstL...43..472G).
Note (4): The vsini is the mean value from the catalogue of Glebocki et al.
(2005yCat.3244....0G 2005yCat.3244....0G) supplemented by values from the literature.
Note (5): The spectral types are mostly from Skiff (2014yCat....102023S 2014yCat....102023S) or the
HD catalogue.
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 27-Jan-2023