J/ApJ/925/114 Gravity modes in HH Puppis Blazhko star with PAIX (Chadid, 2022)
Detection of gravity modes in RR Lyrae stars.
Chadid M.
<Astrophys. J., 925, 114 (2022)>
=2022ApJ...925..114C 2022ApJ...925..114C
ADC_Keywords: Stars, variable; Photometry
Keywords: Observational astronomy ; Photometer ; Astronomy data analysis ;
Pulsating variable stars ; Stellar convection envelopes ;
Stellar pulsations ; RR Lyrae variable stars ; Metallicity ;
Chemical abundances
Abstract:
We report the detection of gravity modes in RR Lyrae stars. Thanks to
Photometer AntarctIca eXtinction (PAIX), the first Antarctic polar
photometer. Unprecedented and uninterrupted UBVRI time-series
photometric ground-based data are collected during 150 days from the
highest plateau of Antarctica. PAIX light-curve analyses reveal an
even richer power spectrum with mixed modes in RR Lyrae stars. The
nonlinear nature of several dominant peaks, showing lower and higher
frequencies, occurs around the dominant fundamental radial pressure
mode. These lower frequencies and harmonics linearly interact with the
dominant fundamental radial pressure mode and its second and third
overtone pressure modes, as well. Half-integer frequencies are also
detected, likewise side-peak structures, demonstrating that HH Puppis
is a bona-fide Blazhko star. Fourier correlations are used to derive
underlying physical characteristics for HH Puppis. The most striking
finding is the direct detection of gravity waves. We interpret the
excitation mechanism of gravity waves in RR Lyrae stars by the
penetrative convection-driving mechanism. We demonstrate that RR Lyrae
stars' pulsation is excited by several distinct mechanisms, and hence
RR Lyrae stars are simultaneously g-mode and p-mode pulsators. Our
discoveries make RR Lyrae stars very challenging stellar objects, and
provide their potential to undergo at the same time g and p modes
toward an advancement of the theory of stellar evolution and a better
understanding of the universe.
Description:
The Photometer AntarctIca eXtinction (PAIX) is attached to the
Cassegrain focus of a 40cm Ritchey-Chretien optical telescope in
Antartica; see Section 2.1.
The PAIX data used in this study are the calibrated light curves from
the magnitude extraction that we measured by PAIX's CCD during an
observing run starting on 2011 May 12 and ending on 2011 September 25.
The 17500 CCD images of the target, HH Puppis, have been collected
through UBVRI color filters with an exposure time Δt≤60s. In
this case, the accumulated observable time spans, without any
interruption, over 136 days of 2011's polar wintertime. See Section 2.2.
Objects:
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RA (ICRS) DE Designation(s)
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07 20 35.55 -46 42 30.1 HH Puppis = V* HH Pu
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 55 115 Relevant frequencies and their Fourier amplitudes,
phases, and their identification
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See also:
J/ApJ/598/597 : Frequencies of fundamental-mode RR Lyrae (Alcock+, 2003)
J/A+A/510/A39 : CoRoT light curves of V1127 Aql (Chadid+, 2010)
J/ApJS/213/31 : Blazhko effect from 4yr of Kepler data (Benko+, 2014)
J/MNRAS/452/4283 : 33 RR Lyrae observed in Pisces with K2-E2 (Molnar+, 2015)
J/MNRAS/487/5584 : First-overtone RR Lyrae stars from OGLE (Netzel+, 2019)
J/AJ/157/153 : Atomic lines in sp. of RR Lyrae & RHB stars (Preston+, 2019)
J/AcA/69/321 : OGLE RR Lyrae stars in Gal. bulge & disk (Soszynski+, 2019)
J/ApJ/908/20 : Field RR Lyrae as galactic probes. II. (Crestani+, 2021)
J/ApJS/258/8 : LCs of RR Lyrae stars from TESS (Molnar+, 2022)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 1 A1 --- Type Type code (1)
3- 12 F10.7 d-1 Freq [0.2/76.002] Frequency
14- 21 F8.6 mag Amp [0.0003/0.4] Amplitude
23- 30 F8.6 --- Phase [0.0076/0.983] Phase
32- 55 A24 --- ID Identifier
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Note (1): Type code as follows:
A = Main fundamental pressure mode frequency and harmonics (30 occurrences);
B = Second and Third overtone mode frequencies, harmonics and sub-harmonics
(5 occurrences);
C = Gravity mode frequencies, harmonics and sub--harmonics (16 occurrences);
D = Blazhko Multiplet frequencies (6 occurrences);
E = Nonradial pressure modes and harmonics (7 occurrences);
F = Linear combinations (51 occurrences).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-Sep-2023