scholarly journals The Pulsation Spectrum of VX Hydrae

2009 ◽  
Vol 121 (884) ◽  
pp. 1076-1082 ◽  
Author(s):  
M. R. Templeton ◽  
G. Samolyk ◽  
S. Dvorak ◽  
R. Poklar ◽  
N. Butterworth ◽  
...  
Keyword(s):  
Pulsation Spectrum

scholarly journals Pulsation spectrum ofδScuti stars: the binary HD 50870 as seen with CoRoT and HARPS

2012 ◽  
Vol 542 ◽  
pp. A24 ◽  
Author(s):  
L. Mantegazza ◽  
E. Poretti ◽  
E. Michel ◽  
M. Rainer ◽  
F. Baudin ◽  
...  
Keyword(s):  
Pulsation Spectrum

ASSESSMENT OF PARASYMPATHETIC CONTROL OF BLOOD VESSEL BY PULSATION SPECTRUM AND COMPARISON WITH SPECTRAL METHOD OF RR INTERVALS

2003 ◽  
Vol 15 (01) ◽  
pp. 8-16
Author(s):  
CHANG-WEI HSIEH ◽  
CHI-WU MAO ◽  
MING-SHING YOUNG ◽  
TZUNG-LIEH YEH
Keyword(s):  
Spectral Method ◽  
High Frequency ◽  
Autonomic Function ◽  
Low Frequency ◽  
Frequency Component ◽  
Short Term ◽  
Non Invasive ◽  
Spectrum Method ◽  
Pulsation Spectrum ◽  
Parasympathetic Control

A new pulse spectrum method of assessing autonomic function was examined in a pharmacological experiment on eight healthy volunteers. The pulse pressure data is obtained under control condition and in parasympathetic blocked by atropine. Compared with the spectral method of heart rate variability (HRV), which is wide-spreading in laboratory studies and clinical diagnosis nowadays, the method of pulsation spectrum provides a new and direct view to assess parasympathetic control. As can be seen from the results, the high frequency of pulsation harmonics are reduced by the parasympathetic blocked, and on the contrary, low frequency component increased. By the analysis of linear regression, the pulsation spectrum method indicates more correlations with atropine doses. We anticipate that the non-invasive assessment of short-term autonomic function will come to be performed more reliably and conveniently by using this method.

The Rich p-Mode Pulsation Spectrum of HD 60435

1988 ◽  
pp. 261-264
Author(s):  
J. M. Matthews ◽  
D. W. Kurtz ◽  
W. H. Wehlau
Keyword(s):  
Pulsation Spectrum ◽  
The Rich

scholarly journals Testing the hot-flasher scenario with asteroseismological tools. First Results

2009 ◽  
Vol 5 (H15) ◽  
pp. 369-369
Author(s):  
M. M. Miller Bertolami ◽  
A. H. Córsico ◽  
L. G. Althaus
Keyword(s):  
White Dwarfs ◽  
Preliminary Investigation ◽  
Chemical Diffusion ◽  
Stellar Model ◽  
Period Range ◽  
Frequency Spectra ◽  
Sdb Stars ◽  
Pulsation Spectrum ◽  
First Results ◽  
Red Giant

AbstractA core helium flash after the departure from the red giant branch (i.e. "hot-flasher scenario") offers one of the most promising explanations for the origin of He-sdO stars. Recently, Miller Bertolami et al. (2008) have shown that many surface properties of H-deficient sdO stars (the He-sdO stars) could be explained through this scenario if chemical diffusion is taken into account. In this context the He-sdO stars formed during a hot-flasher event would transform into H-rich hot-sdB stars (33000-38000 K) as a consequence of diffusion of the remaining H towards the surface of the star. Thus, some hot sdBs might be the descendants of He-sdO stars that have previously burnt most of their H-content and, thus, a very thin H envelope should be expected (10−9 to 10−10 M⊙, see Miller Bertolami et al. 2008 for details). Interestingly enough, the location of these sdB stars in the logg - Teff diagram should overlap with the domain of the rapidly pulsating (p-mode) EC 14026 stars. This fact opens the interesting possibility of employing asteroseismology to investigate the existence of hot-sdB stars characterized by such very thin H envelopes. In this preliminary investigation, we explore the sensitivity of the acoustic pulsation spectrum of EC 14026 stars to the thickness of the H envelope.The pulsation analysis presented in this work was performed with the help of the adiabatic radial and nonradial pulsation code employed by our group in numerous asteroseismological studies of white dwarfs and pre-white dwarfs (see Córsico et al. 2008 and references therein). The stellar models adopted in the present study where extracted from the 0.48150 M⊙ (Z= 0.001) sequence of Miller Bertolami et al. (2008). Given the exploratory nature of this work, in order to analyze the effects of different thicknesses of the H-rich envelope on the pulsation spectrum of sdB stars we have artificially added a H-rich envelope in the outermost layers of our initial model. We have considered four different thicknesses of the H envelope (log Menv/M⊙ ~ −4, −6, −8, −10) in addition to the self-consistent model (which lacks a H envelope). Next, we have pursued the evolution of the five sequences during the evolution on the HB. For each stellar model, we have computed the radial and nonradial p-modes with periods longer than 20 seconds, thus comfortably covering the observed period range of EC 14026 stars (80 - 400 sec).Our results show that the cycle of trapping is markedly smaller for the case of thick H-envelope models (Menv > 10−7 M⊙) than for the thin H-envelope models (Menv < 10−7 M⊙). We find that sdB stars with very thin H envelopes (Menv < 10−7 M⊙) would not display almost any kind of trapping features in their frequency distribution at the observed range in EC 14026 stars (ν < 13 mHz). Consequently their frequency spectra should be significantly different from that of normal sdB stars. We plan to explore in future works to which extent the shape of the chemical transitions (here adopted as simple gaussian profiles) affects the mode-trapping features.

scholarly journals The rich p-mode pulsation spectrum of HD 60435

1988 ◽  
Vol 123 ◽  
pp. 261-264
Author(s):  
J.M. Matthews ◽  
D.W. Kurtz ◽  
W.H. Wehlau
Keyword(s):  
Amplitude Modulation ◽  
Phase Shifts ◽  
Magnetic Rotation ◽  
Rotation Periods ◽  
Pulsation Spectrum ◽  
The Rich ◽  
Ap Stars ◽  
Low Amplitude

Twelve cool Ap stars are known at present to undergo rapid light oscillations at low amplitude (ΔB < 0m.012) and with periods of minutes. These rapidly oscillating Ap (roAp) stars also exhibit amplitude modulation with timescales of days, which correspond to the magnetic/rotation periods (when those have been measured). In at least one case (HR 3831), 180° phase shifts in the dominant oscillation are seen twice per modulation cycle.

Nonradial Pulsations of the DA Type White Dwarf Star G 255-2

2002 ◽  
Vol 185 ◽  
pp. 378-379
Author(s):  
J.-N. Fu ◽  
G. Vauclair ◽  
N. Dolez ◽  
S.-Y. Jiang ◽  
M. Chevreton
Keyword(s):  
White Dwarf ◽  
Photometric Data ◽  
Dwarf Star ◽  
Standard Process ◽  
Pulsation Spectrum

AbstractPhotometric data obtained on the DA type white dwarf star G255-2 between 1991 and 1997 were reduced and the pulsation spectrum was explored with the standard process. The further analysis provides 10 normal, probably l = 1, independent nonradial eigenmodes.

Pulsation spectrum of the mixing layer of an underexpanded jet

1987 ◽  
Vol 28 (3) ◽  
pp. 430-432
Author(s):  
S. A. Novopashin ◽  
A. L. Perepelkin ◽  
V. N. Yarygin
Keyword(s):  
Mixing Layer ◽  
Underexpanded Jet ◽  
Pulsation Spectrum

scholarly journals TESS unveils the phase curve of WASP-33b

2020 ◽  
Vol 639 ◽  
pp. A34 ◽  
Author(s):  
C. von Essen ◽  
M. Mallonn ◽  
C. C. Borre ◽  
V. Antoci ◽  
K. G. Stassun ◽  
...  
Keyword(s):  
Light Curve ◽  
Signal To Noise Ratio ◽  
Phase Curve ◽  
Hot Jupiters ◽  
Brightness Temperatures ◽  
Pulsation Spectrum ◽  
Stellar Pulsations ◽  
Detailed Determination

We present the detection and characterization of the full-orbit phase curve and secondary eclipse of the ultra-hot Jupiter WASP-33b at optical wavelengths, along with the pulsation spectrum of the host star. We analyzed data collected by the Transiting Exoplanet Survey Satellite (TESS) in sector 18. WASP-33b belongs to a very short list of highly irradiated exoplanets that were discovered from the ground and were later visited by TESS. The host star of WASP-33b is of δ Scuti-type and shows nonradial pulsations in the millimagnitude regime, with periods comparable to the period of the primary transit. These completely deform the photometric light curve, which hinders our interpretations. By carrying out a detailed determination of the pulsation spectrum of the host star, we find 29 pulsation frequencies with a signal-to-noise ratio higher than 4. After cleaning the light curve from the stellar pulsations, we confidently report a secondary eclipse depth of 305.8 ± 35.5 parts-per-million (ppm), along with an amplitude of the phase curve of 100.4 ± 13.1 ppm and a corresponding westward offset between the region of maximum brightness and the substellar point of 28.7 ± 7.1 degrees, making WASP-33b one of the few planets with such an offset found so far. Our derived Bond albedo, AB = 0.369 ± 0.050, and heat recirculation efficiency, ɛ = 0.189 ± 0.014, confirm again that he behavior of WASP-33b is similar to that of other hot Jupiters, despite the high irradiation received from its host star. By connecting the amplitude of the phase curve to the primary transit and depths of the secondary eclipse, we determine that the day- and nightside brightness temperatures of WASP-33b are 3014 ± 60 K and 1605 ± 45 K, respectively. From the detection of photometric variations due to gravitational interactions, we estimate a planet mass of MP = 2.81 ± 0.53 MJ. Based on analyzing the stellar pulsations in the frame of the planetary orbit, we find no signals of star-planet interactions.

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