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.
{"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}
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
我们报告在对半人马座球状星团中快速脉动的极端水平分支的搜索中发现了一颗新的脉动EHB星。我们报告了在智利La Silla的3.5 m NTT上收集的2小时SUSI2快速时间序列光度测量数据的基础上搜索ω Cen中快速脉动的极端水平分支(EHB)恒星的结果。观测到的区域覆盖了半人马座东南象限的5.5 ' ×5.5 '，该区域因其密集的EHB，相对较近和较低的红度而被选中，而不是更典型的球状星团。我们使用U滤光片以减少场拥挤，并选择3x3分频将开销时间减少到16 s，再加上20 s的曝光时间，周期时间为36 s，足够低，可以探测到EC 14026型恒星的快速振荡，这是我们变型搜索的主要目标。这些天体构成了亚矮星B (sdB)恒星的一小部分(~ 5%)，这些恒星是位于H-R图EHB上的进化的，核心氦燃烧的天体。虽然它们被认为是在红巨星分支顶端附近遭受巨大质量损失的恒星的后代，但它们形成的细节仍不清楚。希望最终，对其中脉动星震的解释将能够表征sdB种群的质量和氢壳厚度分布，从而有助于区分不同提出的进化情景。在这个方向上的第一次努力看起来很有希望，到目前为止，已经对至少35颗已知的EC 14026恒星中的12颗进行了完整的星震分析(参见Fontaine et al. 2008最近的评论)。然而，到目前为止，所有已知的sdB脉冲星都属于野外种群，尽管在选定的球状星团中对EHB恒星的变异性进行了几次搜索。我们用SUSI2监测的磁场与用WFI在2.2 m ESO/MPI望远镜上收集的ω Cen的uvi波段光度完全重叠(Castellani et al. 2007)。同时对获得的192个SUSI2帧进行psf拟合光度测定，导致检测到约20,000颗恒星，其中我们能够从WFI目录中选择潜在的EC 14026候选恒星，其亮度(16≤U≤18.5)，颜色(- 2≤(U−V)≤- 0.8)，光度精度，清晰度和分离指数。对于这样确定的52颗EHB恒星，我们计算了空气质量，并观察了与SUSI2平均u波段星等相关的校正光曲线。请注意，后者未经校准，因此不构成标准星等。然后，我们计算了S. K. Randall, A. Calamida和G.Bono的傅里叶变换89图1:ω半人马座发现的脉动EHB恒星的光曲线(上)和傅里叶变换(下)。请注意，光曲线上显示的相对u等与WFI目录上的绝对u等相差约+0.25等。主脉冲周期为114s，而外观奇特的次峰对应于奈奎斯特频率。水平虚线表示4σ检测阈值。(FT)在1−15 mHz范围内的每个光曲线，适用于检测EC 14026脉冲器预期的脉动。在选定的52个候选对象中，有一个在FT中显示出高于施加的检测阈值4σ的可信峰值。它的光曲线和傅里叶变换如图1所示，其中114-s (8.75 mHz)的峰值被认为表明恒星振荡，以及72 s (13.9 mHz)的观测伪像对应于奈奎斯特频率都可见。后者是在大多数监测目标中遇到的，而前者是所显示的恒星所特有的。这加强了发现恒星真实变异性的理由，而不是仪器或观测特征。这颗变星的周期与EC 14026恒星典型的100 - 200秒的脉动相吻合。此外，将观测到的光学颜色与适用于ω Cen的水平分支模型进行比较表明，该天体的有效温度为31,500±6,300 K，完全处于快速振荡的亚矮星B的29,000−36,000 K不稳定带内。因此，我们非常有信心，我们已经在球状星团中发现了第一颗EC 14026恒星。90在ω - Cen中对极端水平分支脉动的搜索。关于本文工作的更多细节可以在Randall et al. 2009中找到。致谢S.K.R.在此感谢ESO La Silla的工作人员，特别是SUSI2仪器科学家Alessandro Ederoclite。遗憾的是，这里报告的观测结果是自SUSI2仪器退役以来最后一次获得的观测结果。
{"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}
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
{"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}
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
{"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}
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.
{"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}
T. Kallinger, D. Guenther, W. Weiss, M. Hareter, J. Matthews, R. Kuschnig, P. Reegen, G. Walker, S. Rucinski, A. Moffat, D. Sasselov
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
基于加拿大微型卫星most 1对K巨星HD20884近连续20.6天的高精度光度测量，我们发现了其振荡谱中存在径向p模和非径向混合模的证据，振荡频率范围为5 ~ 31 μ Hz(周期约2.3d ~ 9hr)，光度幅值约为300 ~ 950 ppm，模态寿命超过10天。模式识别是基于对最适合hd20884频率和温度的大型模型网格的搜索。作为这项工作的一部分，David Dunlap天文台所获得的光谱学对后者有了更好的约束。单个天体:HD20884, HD20790， κ 1 Ceti， ǫOph, hya, HD146490简介在过去的三十年里，太阳地震学彻底改变了我们对太阳结构的理解。这项技术可以通过观测恒星表面的p模来研究太阳内部。在很长一段时间内，观测其他恒星的类似太阳的振荡受到极小脉动幅度的阻碍。对于比太阳更冷、更亮的恒星，预期的振幅更大，应该更容易观察到。然而，半径较大的红巨星将它们的脉动周期从太阳的5分钟延长到几小时到几天。这再次使地基探测和频率识别复杂化，特别是由于日常混叠。随着来自太空的超精确快速光度测量和来自地面的高精度径向速度测量变得可用，对几个巨星的随机驱动振荡的检测被报道(见Bouchy & Carrier 2003年的评论)。例如，根据coralie和ELODIE光谱仪(De Ridder etal. 2006)的径向速度，以及most卫星(Barbanetal)的Fabry成像光度测定，G9.5巨星ǫOph。2007)，以及基于CORALIE光谱仪径向速度测量的g7giant - hya (Frandsen et al. 2002)，或者Kallinger et al.(2005)基于哈勃太空望远镜的精密制导传感器光度测量发现了振荡的K2.5巨星GSC09137-03505。如果脉动红巨星确实具有相对较长的寿命的径向和可观测的非径向模式，那么这些模式将能够约束红巨星的深层内部，并为激发机制设定限制。但最近的研究(如Barban et al. 2007或Stello et al. 2006)表明，只有寿命非常短(< 3天)的辐射模态才能在红巨星中观测到。另一方面，Kallinger等人(2008b)报告了在ǫOph中存在径向和非径向模式(寿命超过10天)的有力证据
{"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}
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
我们对λBootis群的所有成员进行了可用的Hipparcos历元光度分析。除了已知的δ Scuti脉动频率外，我们还搜索了由双星或旋转引起的变化引起的日食。hd15165的已知频率被确认为另一个较低的单频率，这可能是由吸积事件引起的。但我们不能排除可能的混叠由于数据集的时间采样。此外，还发现了三个可能发生日食的候选天体(HD 15759、HD 120500和HD 149130)。否则，频率分析在我们严格的检测范围内显示为空结果。单个对象: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,高清192640，高清198160，高清204041，高清210111，高清221756
{"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}
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
{"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}
L. Machado, R. Michel, M. Álvarez, L. Parrao, A. Castro, J. Pena
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.
{"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}
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