Third Coast最新文献

{"title":"Cinderella User's Manual","authors":"P. Reegen","doi":"10.1553/CIA163S99","DOIUrl":"https://doi.org/10.1553/CIA163S99","url":null,"abstract":"Cinderella is a software solution for the quantitative comparison of time series in the frequency domain. It assigns probabilities to coincident peaks in the DFT amplidude spectra of the datasets under consideration. Two different modes are available. In conditional mode, Cinderella examines target and comparison datasets on the assumption that the latter contain artifacts only, returning the conditional probability of a target signal, although there is a coincident signal in the comparison data within the frequency resolution. In composed mode, the probability of coincident signal components in both target and comparison data is evaluated. Cinderella permits to examine multiple target and comparison datasets at once.","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130105106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A search for Extreme Horizontal Branch pulsators in ω Cen","authors":"S. Randall, A. Calamida, G. Bono","doi":"10.1553/CIA159S88","DOIUrl":"https://doi.org/10.1553/CIA159S88","url":null,"abstract":"We report the discovery of a new pulsating EHB star from a search for rapidly pulsating Extreme Horizontal Branch in the globular cluster ω Cen. Individual Objects: ω Cen We report on the outcome of a search for rapidly pulsating Extreme Horizontal Branch (EHB) stars in ω Cen on the basis of 2 hours of SUSI2 rapid time-series photometry gathered at the 3.5-m NTT on La Silla, Chile. The field observed covers 5.5’×5.5’ in the southeastern quadrant of ω Cen, which was selected over more typical globular clusters for its well-populated EHB, as well as its relative proximity and low reddening. We used a U filter in order to minimize field crowding, and chose 3x3 binning to reduce the overhead time to 16 s, which combined with the exposure time of 20 s resulted in a cycle time of 36 s, low enough to detect the rapid oscillations expected in EC 14026 type stars, the main targets of our variability search. These objects make up a small fraction (∼ 5%) of subdwarf B (sdB) stars, which are evolved, core-helium burning objects located on the EHB of the H-R diagram. While they are thought to be the progeny of stars that suffered significant mass loss near the tip of the Red Giant Branch, the details of their formation remain unclear. It is hoped that eventually, the asteroseismic interpretation of the pulsators among them will enable a characterization of the mass and hydrogen-shell thickness distribution of the sdB population and thus help discriminate between different proposed evolutionary scenarios. First efforts in this direction appear promising, full asteroseismic analyses having so far been carried out for 12 out of at least 35 known EC 14026 stars (see Fontaine et al. 2008 for a recent review). However, until now, all known sdB pulsators belonged to the field population, despite several searches for variability among EHB stars in selected globular clusters. The field we monitored with SUSI2 completely overlaps with available UBVI-band photometry of ω Cen gathered with WFI on the 2.2-m ESO/MPI telescope (Castellani et al. 2007). Performing simultaneous PSF-fitting photometry on the 192 SUSI2 frames obtained led to the detection of ∼ 20,000 stars, of which we were able to select potential EC 14026 star candidates from the WFI catalogue in terms of brightness (16 ≤ U ≤ 18.5), colour (−2 ≤ (U − V ) ≤ −0.8), photometric accuracy, sharpness and separation index. For the 52 EHB stars thus identified we computed the airmass and seeing corrected light curves with respect to the mean SUSI2 u-band magnitude. Note that the latter was not calibrated and does therefore not constitute a standard magnitude. We then computed the Fourier transform S. K. Randall, A. Calamida, and G.Bono 89 Figure 1: Light curve (top) and Fourier transform (bottom) for the pulsating EHB star discovered in ω Cen. Note that the relative u magnitude indicated for the light curve is offset by around +0.25 magnitudes with respect to the absolute U magnitude from the WFI catalogue. The domin","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122988200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Asteroseismology of pre-main sequence stars","authors":"K. Zwintz, D. Guenther, T. Kallinger","doi":"10.1553/CIA159S59","DOIUrl":"https://doi.org/10.1553/CIA159S59","url":null,"abstract":"Intermediate-mass pre-main sequence (PMS) stars cross the instability region on their way to the main sequence and can become pulsationally unstable. The δ Scuti-like PMS pulsators populate the same area in the Hertzsprung-Russell (HR) diagram as the classical δ Scuti stars. But the interiors of PMS stars differ from those of their more evolved (post-)main sequence counterparts resulting in different pulsation frequency spectra. Asteroseismology of PMS p-mode pulsators has only recently become possible. The latest investigation focused on the analysis of MOST space photometry of the Herbig Ae star HD 142666 finding 12 pulsational frequencies lying on top of larger irregular variability caused by a circumstellar disk. Individual Objects: HD 142666","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124493122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Asteroseismology of chemically peculiar stars","authors":"O. Kochukhov","doi":"10.1553/cia159s61","DOIUrl":"https://doi.org/10.1553/cia159s61","url":null,"abstract":"Pulsational variability is observed in several types of main sequence stars with anomalous chemical abundances. In this contribution I summarize the relationship between pulsations and chemical peculiarities, giving special emphasis to rapid oscillations in magnetic Ap stars. These magneto-acoustic pulsators provide unique opportunities to study the interaction of pulsations, chemical inhomogeneities, and strong magnetic fields. Time-series monitoring of rapidly oscillating Ap stars using high-resolution spectrometers at large telescopes and ultra-precise space photometry has led to a number of important breakthroughs in our understanding of these interesting objects. Interpretation of the roAp frequency spectra has allowed constraining fundamental stellar parameters and probing poorly known properties of the stellar interiors. At the same time, investigation of the pulsational wave propagation in chemically stratified atmospheres of roAp stars has been used as a novel asteroseismic tool to study pulsations as a function of atmospheric height and to map in detail the horizontal structure of the magnetically-distorted p modes. Individual Objects: HR 8799, HD 116114, HD 201601 (γ Equ), HD 176232 (10 Aql), HD 134214, HD 137949 (33 Lib), HD 99563, HD 24712, HD 75445, HD 137909 (β CrB), HD 101065, HR 3831","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133417192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Asteroseismic modeling of the pulsating B star HD 163830","authors":"D. Pricopi, M. Suran","doi":"10.1553/CIA_153S28","DOIUrl":"https://doi.org/10.1553/CIA_153S28","url":null,"abstract":"In this paper, we report our preliminary results regarding the asteroseismic modeling of the slow pulsating B star HD 163830, based on eighteen of the twenty detected frequencies of this star. The powerful method of matching stellar models both to oscillation data and eective temperature and gravity of HD 163830 is applied to identify a best-t model. These eighteen frequencies correspond to low-order, high-degree g-modes of an stellar model of 1:016 10 8 yr, of a 4:4M star with chemical composition X = 0:71, Z = 0:02.","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129699312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MOST found evidence for solar-type oscillations in the K2 giant star HD 20884","authors":"T. Kallinger, D. Guenther, W. Weiss, M. Hareter, J. Matthews, R. Kuschnig, P. Reegen, G. Walker, S. Rucinski, A. Moffat, D. Sasselov","doi":"10.1553/CIA_153S84","DOIUrl":"https://doi.org/10.1553/CIA_153S84","url":null,"abstract":"Abstract We found evidence for radial p-modes and nonradial mixed modes in the oscilla-tion spectrum of the K giant HD20884 based on 20.6 days of nearly continuoushigh-precisionphotometryobtainedbytheCanadianmicrosatelliteMOST 1 .Os-cillation frequencies range from 5-31µHz (periods of about 2.3d - 9hr) withluminosity amplitudes between about 300 and 950 ppm and mode lifetimes ex-ceeding 10 days are indicated. The mode identifications are based on searchesof a large grid of models for a best fit to the frequencies and temperature ofHD20884. The latter is better constrained now by spectroscopy obtained atthe David Dunlap Observatory as part of this work. Individual Objects: HD20884, HD20790, κ 1 Ceti, ǫOph, ξHya, HD146490 Introduction Our understanding of the Sun’s structure has been revolutionised over the last threedecades by helioseismology. This technique allows investigations of the solar interiorby observing p-modes at the stellar surface. Observing sun-like oscillations in otherstars was hampered for a long time by the extremely small pulsation amplitudes. Forstars cooler and more luminous than the Sun, the expected amplitudes are greater andshould be more easily observable. However, the larger radii of red giants extend theirpulsation periods from ∼5 minutes in the Sun to a range of several hours to severaldays. This again complicates groundbased detections and frequency identifications,especially due to daily aliasing.As ultra-precise rapid photometry from space and high-precision radial velocitymeasurements from the ground became available, detections of stochastically drivenoscillations were reported for several giants (see Bouchy & Carrier 2003 for a review).Examples include the G9.5 giant ǫOph, based on radial velocities from the CORALIEand ELODIE spectrographs (De Ridder et al. 2006) and Fabry Imaging photometryfromtheMOSTsatellite(Barbanetal. 2007), andtheG7giantξHya, basedonradialvelocity measurements with the CORALIE spectrograph (Frandsen et al. 2002), orthe K2.5 giant star GSC09137-03505 where Kallinger et al. (2005) found oscillations,based on Fine Guidance Sensor photometry by the Hubble Space Telescope.If pulsating red giants do indeed have radial and observable nonradial modes withrelatively long lifetimes, then these modes will enable to constrain the deep interiorof red giant stars, as well as set limits to the excitation mechanisms. But recentinvestigations (e.g., Barban et al. 2007 or Stello et al. 2006 ) suggest that only radialmodes with very short lifetimes (< 3 days) should be observable in red giants. Onthe other hand, Kallinger et al. (2008b) report strong evidence for the existence ofradial and nonradial modes in ǫOph (with lifetimes longer than 10 days) based on","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126072399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysing the Hipparcos epoch photometry of γ Bootis stars","authors":"E. Paunzen, P. Reegen","doi":"10.1553/CIA_153S49","DOIUrl":"https://doi.org/10.1553/CIA_153S49","url":null,"abstract":"We performed a homogeneous analysis of the available Hipparcos epoch photometry for all members of the λBootis group. Besides the known δ Scuti like pulsation frequencies, we searched for eclipses due to binarity or rotational induced variability. The already known frequencies of HD 15165 are confirmed with an additional lower single frequency, which might be caused by an accretion episode. But we are not able to rule out a possible aliasing due to the temporal sampling of the data set. Furthermore, three candidates (HD 15759, HD 120500, and HD 149130) for a possible eclipse were detected. Otherwise, the frequency analysis reveals a null result within our strict detection limits. Individual Objects: HD 319, HD 6870, HD 7908, HD 11413, HD 13755, HD 15165, HD 15759, HD 23392, HD 24472, HD 30422, HD 31295, HD 35242, HD 64491, HD 74873, HD 75654, HD 81290, HD 83041, HD 83277, HD 84123, HD 84948, HD 87271, HD 91130, HD 101108, HD 102541, HD 105058, HD 106223, HD 107233, HD 110411, HD 111005, HD 111604, HD 111786, HD 120500, HD 120896, HD 125162, HD 130767, HD 141851, HD 142703, HD 149130, HD 153747, HD 154153, HD 156954, HD 160928, HD 168740, HD 170680, HD 171948, HD 175445, HD 183324, HD 192640, HD 198160, HD 204041, HD 210111, HD 221756","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114104817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wroc_aw HELAS Webpage","authors":"J. Daszyńska-Daszkiewicz, Wrocaw, Warsaw Helas Team","doi":"10.1553/CIA_153S106","DOIUrl":"https://doi.org/10.1553/CIA_153S106","url":null,"abstract":"","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115965535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photometric detection of pulsations in the stars of the wide binary WDS 12483-6708","authors":"D. Sinachopoulos, P. Gavras","doi":"10.1553/CIA_153S17","DOIUrl":"https://doi.org/10.1553/CIA_153S17","url":null,"abstract":"We detected stellar pulsations in at least one of the components of the wide double star WDS 12483-6708. The largest observed photometric amplitude, in Stroemgren filter y, is around 0.02 magnitudes with period about 0.02 days. The detection was based on five hours of differential CCD photometry of the two double star components. Individual Objects: WDS 12483-6708, HIC 62482, HIC 62488 Introduction and Observations WDS 12483-6708 is a wide double star detected in 1835. Since then, the relative positions of its components have been observed 16 times. The last observation listed in the Washington Double Star Catalogue (WDS) (Mason & Hartkopf 2006) is from the year 2000, when the angular separation of the components measured was 13.5 arcseconds. The primary of the system is a A3III/IV type star. It is the HIC 62482 target of Hipparcos with V=7.58, (B−V) = 0.19 and parallax 10mas. The secondary star is HIC 62488 with magnitude V=8.74, (B − V) = 0.47 and has practically the same parallax of the primary. The proper motions of the two components are the same (common proper motion stars). These two facts show that this double star is not an optical pair. Hipparcos catalogue (ESA 1997) flags both components for ’duplicity-induced’ variability. Figure 1: A characteristic CCD exposure of WDS 12483-6708 in Stroemgren y filter 18 Photometric detection of pulsations in the wide binary WDS 12483-6708 Figure 2: Variability of the magnitude difference of the components of WDS 12483 − 6708, together with the fit of the two detected frequencies. We observed this double star in May 16, 2004, in the frame of astrometric observations of wide Hipparcos visual double stars (Sinachopoulos et al. 2007), using the STE4 CCD camera of SAAO observatory attached to the Cassegrain focus of the 1m telescope, using the Stroemgren y filter. To improve the instrumental accuracy of our measurements, especially the astrometric ones, we obtained sixteen CCD exposures of each double star similar to the image shown in Figure 1. Our -quasion-line data reduction resulted in an unexpectedly high value of the standard deviation of measured mean magnitude difference of the double star components. Since these two stars are in or close to the instability strip of the MS, we decided to spend five hours monitoring them photometrically. To our regret, there is no other star close WDS 12483-6708 bright enough which could be used as a comparison star, so we could only measure the variability of the magnitude difference of the two components. We took a series of ten-second exposures, which together with the CCD readout time resulted in 95 magnitude differences per hour. Our measurements are shown in Figure 2. Frequency analysis The light curve shows significant variability during the observational window. The largest amplitude we see in our measurements is about 0.02 mag. Consequently, Fourier analysis was performed using Period04 (Lenz & Breger 2005). Two frequencies were detected and listed in Tab","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133565624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CCD photometry of δ Scuti stars 7 Aql and 8 Aql","authors":"L. Machado, R. Michel, M. Álvarez, L. Parrao, A. Castro, J. Pena","doi":"10.1553/cia_153s20","DOIUrl":"https://doi.org/10.1553/cia_153s20","url":null,"abstract":"As a continuation of the study of the Delta Scuti stars 7 Aql and 8 Aql; new CCD photometric data were acquired in 2007. We present a period analysis on these data that confirm the dominant modes detected in each star in the framework of the STEPHI XII campaign in 2003.","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121052689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}