Mode identification based on time-series spectrophotometry for the bright rapid sdB pulsator EC 01541−1409

AbstractTime-series of high-resolution spectra of massive main-sequence pulsators contain information on the degree l and azimuthal number m of a pulsation mode. I present an overview of existing mode-identification techniques that have been developed to derive l and m from spectroscopic data. I also discuss the data quality needed to perform such a study. Through some examples from the literature I show that the optimal way to identify modes in heat-driven non-radial pulsators is by 1) using multi-site campaign data, 2) combining different spectroscopic mode-identification techniques, and 3) combining results from photometric and spectroscopic mode-identification studies.

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PG 1605+072 in Wet XCov22: Support for the Multi Site Spectroscopic Telescope

Open Astronomy ◽

10.1515/astro-2017-0034 ◽

2003 ◽

Vol 12 (1) ◽

Author(s):

S. L. Schuh ◽

U. Heber ◽

S. Dreizler ◽

S. O’Toole ◽

C. S. Jeffery ◽

...

Keyword(s):

Time Series ◽

Virtual Instrument ◽

Significant Contribution ◽

Frequency Resolution ◽

Paper Briefly ◽

Mode Identification ◽

Photometric Monitoring ◽

Observational Effort ◽

Whole Earth

AbstractThe Multi-site spectroscopic telescope is a virtual instrument and the name of a collaboration that opens up a new observational window by combining continuous observations of spectroscopic variations and simultaneous photometric monitoring. This constitutes an enormous observational effort, but in return promises to finally provide access to a mode identification for and an asteroseismological analysis of the pulsating sdB star PG 1605+072. Multi-Site Spectroscopic Telescope observations for this object have been secured during a large coordinated campaign in May and June of the year 2002. The frequency resolution and coverage of the photometric time series has been noticeably enhanced by a significant contribution from the Whole Earth Telescope, which was used to observe PG 1605+072 as an alternate target during the WET XCov22 campaign, also conducted in May 2002. This paper briefly outlines the motivation for the MSST project and tries to give a first assessment of the overall quality of the data obtained, with a focus on the Whole Earth Telescope observations.

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Time-Series Spectroscopy of EC 14026 Stars: Preliminary Results

International Astronomical Union Colloquium ◽

10.1017/s025292110005870x ◽

2000 ◽

Vol 176 ◽

pp. 519-520

Author(s):

Simon J. O’Toole ◽

Teresa C. Teixeira ◽

Timothy R. Bedding ◽

Hans Kjeldsen

Keyword(s):

Time Series ◽

Equivalent Width ◽

Oscillation Mode ◽

Maximum Amplitude ◽

Mode Identification ◽

Preliminary Results ◽

Previous Time ◽

Velocity Variations ◽

Width Measurements

AbstractWe have obtained time-series spectra for the pulsating hot subdwarf (sdB) PG1605+072. Previous time-series photometry of this star has shown maximum amplitude variations of ∼0.1 mag and at least 50 periods. The pulsator has the largest amplitude and longest periods of all the pulsating sdBs (or EC 14026 stars) discovered so far, and appears to be unusual in its class. Preliminary results of a search for velocity variations are presented here. With these variations, along with equivalent width measurements, oscillation mode identification should be possible.

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Revisiting the pulsational characteristics of the exoplanet host star β Pictoris

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834744 ◽

2019 ◽

Vol 627 ◽

pp. A28 ◽

Cited By ~ 7

Author(s):

K. Zwintz ◽

D. R. Reese ◽

C. Neiner ◽

A. Pigulski ◽

R. Kuschnig ◽

...

Keyword(s):

Magnetic Field ◽

Time Series ◽

Magnetic Properties ◽

Circumstellar Disk ◽

Dipolar Field ◽

Orbital Inclination ◽

Mode Identification ◽

Amplitude Variability ◽

Upper Limit ◽

Host Stars

Context. Exoplanet properties crucially depend on the parameters of their host stars: more accurate stellar parameters yield more accurate exoplanet characteristics. When the exoplanet host star shows pulsations, asteroseismology can be used for an improved description of the stellar parameters. Aims. We aim to revisit the pulsational properties of β Pic and identify its pulsation modes from normalized amplitudes in five different passbands. We also investigate the potential presence of a magnetic field. Methods. We conducted a frequency analysis using three seasons of BRITE-Constellation observations in the two BRITE filters, the about 620-day-long bRing light curve, and the nearly 8-year-long SMEI photometric time series. We calculated normalized amplitudes using all passbands and including previously published values obtained from ASTEP observations. We investigated the magnetic properties of β Pic using spectropolarimetric observations conducted with the HARPSpol instrument. Using 2D rotating models, we fit the normalized amplitudes and frequencies through Monte Carlo Markov chains. Results. We identify 15 pulsation frequencies in the range from 34 to 55 d−1, where two, F13 at 53.6917 d−1 and F11 at 50.4921 d−1, display clear amplitude variability. We use the normalized amplitudes in up to five passbands to identify the modes as three ℓ = 1, six ℓ = 2, and six ℓ = 3 modes. β Pic is shown to be non-magnetic with an upper limit of the possible undetected dipolar field of 300 Gauss. Conclusions. Multiple fits to the frequencies and normalized amplitudes are obtained, including one with a near equator-on inclination for β Pic, which corresponds to our expectations based on the orbital inclination of β Pic b and the orientation of the circumstellar disk. This solution leads to a rotation rate of 27% of the Keplerian breakup velocity, a radius of 1.497 ± 0.025 R⊙, and a mass of 1.797 ± 0.035 M⊙. The ∼2% errors in radius and mass do not account for uncertainties in the models and a potentially erroneous mode-identification.

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Spectroscopic Nonadiabatic Observables as a New Tool for Mode Identification in β Cep Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100016031 ◽

2002 ◽

Vol 185 ◽

pp. 212-215

Author(s):

J. Daszyńska ◽

H. Cugier

Keyword(s):

Time Series ◽

Line Profile ◽

Phase Difference ◽

Inclination Angle ◽

Amplitude Ratio ◽

New Method ◽

Mode Identification ◽

Diagnostic Values ◽

Profile Changes ◽

Almost All

AbstractWe present a new method of mode identification based on the line profile variations. We calculate time series of Si III 455.26 nm for models of β Cep stars with a mass of 10 M⊙. The Spectroscopic observables are amplitude ratio and phase difference for various oscillation parameters derived from the line profile changes. Based on the computed values we plot diagrams to search for the best discriminators of modes.In most Spectroscopic diagrams the unstable modes are grouped in well-defined regions with different m-values, and a few of them give also separation with respect to l-values. Moreover, on the basis of almost all of the diagrams we can distinguish the prograde modes from the retrograde ones, and the zonal modes from those with m ≠ 0.In this paper we discuss also the influence of the inclination angle, the amplitude of the radius variation and the equatorial velocity on the diagnostic values of the Spectroscopic diagrams.

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The eclipsing binary IU Per and its intrinsic oscillations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308023417 ◽

2008 ◽

Vol 4 (S252) ◽

pp. 429-430

Author(s):

X. B. Zhang

Keyword(s):

Time Series ◽

Binary System ◽

Fourier Analysis ◽

Primary Component ◽

Eclipsing Binary ◽

Mode Identification ◽

Short Period ◽

Photometric Solution

AbstractThe results of a long-term time-series photometry of the short-period eclipsing binary IU Per are reported. The observation confirms the intrinsic δ Scuti-like pulsation of the star as discovered by previous authors. A photometric solution for the binary system was carried out with the new data. Based on which, the pure oscillation light variations from the mass-accreting primary component were extracted. A Fourier analysis reveals four pulsation modes. Combining with the photometric solution, a preliminary mode identification was given.

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The LDE-Type Flare Occurrence (1969-1993)

International Astronomical Union Colloquium ◽

10.1017/s0252921100025458 ◽

1994 ◽

Vol 144 ◽

pp. 279-282

Author(s):

A. Antalová

Keyword(s):

Time Series ◽

Fourier Analysis ◽

Sunspot Cycle ◽

List Type ◽

Type Number ◽

Solar Cycles ◽

Type Iv ◽

Long Duration ◽

Cycle Maximum ◽

Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

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