Third Coast最新文献

{"title":"Asteroseismology of Procyon: Preliminary results from SARG","authors":"R. Claudi, A. Bonanno, R. Ventura, G. Bonanno, R. Cosentino, S. Desidera, R. Gratton, S. Scuderi, M. Endl","doi":"10.1553/CIA145S51","DOIUrl":"https://doi.org/10.1553/CIA145S51","url":null,"abstract":"The F5 IV-V subgiant Procyon was observed over 6 nights with SARG at TNG. We took sequences of 10 s exposures with an average dead time in between of 127 s. In total, 956 spectra were collected with a typical signal-to-noise ratio ranging between 250-330. Data reduction was performed using IRAF tasks devoted to echelle spectra. Successively the modelling of the star plus iodine absorption spectra was performed by using AUSTRAL code (Endl et al. 2000, A&A, 362, 585) in order to obtain the radial velocities time series. The Scargle and Lomb modified periodogram (Lomb 1976, Ap&SS, 39, 447, Scargle 1982, ApJ, 263, 835) shows two prominent frequencies: ν1 = 0.2346 mHz and ν2 = 0.8387 mHz both with a significance level greater than 99% . Frequency ν2 corresponds to the 20 min period found by Brown et al. (1991 ApJ, 368, 599).","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113978276","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":"High Amplitude δ Sct-type variables","authors":"E. Rodriguez","doi":"10.1553/CIA145S40","DOIUrl":"https://doi.org/10.1553/CIA145S40","url":null,"abstract":"Historically, the high amplitude δ Sct-type variables (δ Sct pulsators with full amplitudes larger than 0.m3) have been considered as a separated group from the “normal” low amplitude δ Sct variables on the basis, mainly, of their pulsation amplitudes. This has been a subject of controversy by a number of authors. After the review papers by Breger (1979, 1980), the commonly accepted idea is that, independently of the amplitude, the δ Sct variables are normal Population I stars in, or evolving off, the main sequence according to standard stellar evolution theory. This excludes the recently discovered pre-main sequence δ Sct pulsators. Nevertheless, some differences remain and some interesting aspects make these high amplitude objects very useful.","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122185275","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":"SZ Lyn: New pulsational and orbital elements based on old and recent photometric observations","authors":"K. Gazeas, P. Niarchos, K. Boutsia","doi":"10.1553/CIA145S47","DOIUrl":"https://doi.org/10.1553/CIA145S47","url":null,"abstract":"SZ Lyncis (=HD 67390) is a high amplitude δ Scuti star, discovered by Hoffmeister in 1949. Van Genderen (1967) noticed that the residuals in the O-C diagrams followed a sinusoidal variation with a period of Porb = 3.091 years. Several years later, Barnes & Moffett (1975) improved this period to Porb = 3.138 years and suggested that the sinusoidal variations in the O-C diagrams, observed by van Genderen (1967), originate from the light travel time effect, since SZ Lyn is a member of a binary system. This hypothesis was confirmed by Bardin & Imbert (1984) with measurements of radial velocities. Soliman et al. (1986) found the pulsation period to be 0.120534896 days and the orbital period 1173.5 days. From BVRI observations during the period January 1975 March 1979, Moffett et al. (1988) estimated the pulsational period as 0.12052115 days, which is shorter than earlier determinations. The latest research was made by Paparo et al. (1988), who determined the pulsational and orbital elements of the system even better, using all available data from 1961 until 1988. In this paper we present the results of new CCD time-series photometry carried out at the University of Athens Observatory. Our new BVRI CCD photometric observations and those obtained by Derekas et al. (2003) and Hipparcos (ESA 1997) extended the time base of the data from 27 to 42 years (or from 8 to 14 revolutions of the system). The 165 times of maxima observed between 1961 and 2003 were used to calculate the pulsational and orbital elements of the binary system. A new ephemeris was calculated with the new times of maxima, derived from our light curves: tmax(HJD) = 2452776.289(10) + 0d.1205349(41)×E; From a least squares fit to all available O-C values we were able to calculate more precise values of the following parameters: the linear change in the star’s pulsational period (β=2.90±0.22 × 10−12 days/cycle), the orbital period (Porb=1179.3±2 days), the semimajor axis (a sin i=0.998±0.04 AU), the eccentricity (e=0.205±0.010), the longitude and time of the periastron passage (ω=87.6±1.1 degrees and T (HJD)=2445699.8436±0.022) and the mass function f(M)=0.095±0.008.","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126598615","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":"Relevant issues in the study of Pre-Main Sequence Delta Scuti stars","authors":"M. Marconi, V. Ripepi, F. Palla, A. Ruoppo","doi":"10.1553/CIA145S59","DOIUrl":"https://doi.org/10.1553/CIA145S59","url":null,"abstract":"We will review the theoretical and observational developments in the study of Pre-Main Sequence (PMS) δ Scuti stars and point out some current open problems. In particular, we stress the strong need for multi-site and/or space-based observations and for nonradial pulsation modelling. The most recent observations of the best studied object, V351 Ori, and the preliminary results of the application of a nonradial code to PMS δ Scuti stars will also be discussed.","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127147084","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":"Short-Period Variables in ASAS Photometry","authors":"J. Molenda–Żakowicz","doi":"10.1553/CIA145S48","DOIUrl":"https://doi.org/10.1553/CIA145S48","url":null,"abstract":"We present results of our study of short–period variables in ASAS photometry. We focus on slowly pulsating B stars (SPBs), most of which were discovered by the Hipparcos satellite. We discuss the problem of aliasing in the ASAS photometry and its influence on the identification of frequencies of SPBs. Finally, we show that the ASAS photometry can be used not only to confirm the Hipparcos frequencies and amplitudes but it can also give new results for selected SPBs. Introduction The ASAS (All Sky Automatic Survey) project aims for monitoring variability of all objects in the sky brighter that 14 mag. Its prototype instrument and data pipeline were developed by Dr. Pojmański (Pojmański 1997). In 1997–2000 ASAS observed in the I–band (ASAS– 2 project) and since 2001 in V (ASAS–3 project). It succeeded in discovering more than 5 500 new variables (Pojmański 2000 and 2002) and was used for studying Cepheids in the Magellanic Clouds (Pietrukowicz 2001, 2002) and the Galaxy (Beltrame & Poretti 2002). In this work, we analyze ASAS–3 photometry of stars classified as SPB in the Hipparcos Catalogue (ESA 1997). We discuss ASAS observing and spectral window and present results obtained for selected stars. Observing and Spectral Windows In the ASAS–3 observing schedule each of the preselected fields is observed once per night. However, the fields overlap so that many stars are observed several times per night. We show a typical ASAS observing window in the left panel of Fig. 2. This window (compiled for HD52057 from three separate data sets) covers a time span of 2.3 years and consists of 152 observations indicated by impulses. In this figure, Observations are gathered in three clumps inside which sampling is close to one per night. Observations sampled more frequently are rare but also present. Such sampling produces significant daily aliases in the spectral window; in the left panel of Fig. 1 we show an example – the spectral window computed for IS Lup. Windows of this shape, with daily aliases getting lower for higher frequencies, can be computed for ∼ 50% stars observed by ASAS. The other stars have spectral windows with a 2 c/d peak higher than the one at 1 c/d. We find such spectral windows for stars which were observed at the beginning and then at the end of the majority of observing nights. As an example, we show the spectral window for HD52057 in the middle panel of Fig. 1 . For few stars we find spectral windows with the 3 c/d peak higher than the 1 and 2 c/d ones. Windows of this shape occur for stars which are observed sparsely and for which observations are clumped in J. Molenda–Żakowicz 49 8.86 8.87 8.88 8.89 8.9 8.91 8.92 8.93 8.94 8.95 8.96 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 ’032101.hp’","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126734157","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 Variable Star Survey of the Open Cluster NGC 2126","authors":"A. Gáspár, L. Kiss, A. Derekas","doi":"10.1553/CIA145S68","DOIUrl":"https://doi.org/10.1553/CIA145S68","url":null,"abstract":"We present the first CCD photometric observations of the northern open cluster NGC 2126 in the constellation Auriga. Johnson-Cousins V(RI)C data (with a total time span of ∼57 hours) were taken on eight nights in 2002 February and December at the Piszkestető Station of the Konkoly Observatory, using the 60/90/180-cm Schmidt telescope. We have discovered six new variable stars and have estimated the main characteristics of the cluster. The results of the project can be summarized as follows. Cluster parameters were estimated by fitting isochrones (Bertelli et al. 1994) to the colour-magnitude diagrams. In order to decrease foreground contamination, we have examined the proper motion distribution of stars in the field using data taken from the USNO B-1.0 catalogue (the cluster itself has undetected proper motion). To minimize the effects of background stars, we used only the inner 8 of the cluster. The resulting physical parameters are: m − M = 11. m0 ± 0. m5, E(B − V ) = 0. m2± 0. m15, d = 1.3± 0.6kpc. Of the six variables, V1 and V2 showed clear variability, however, our dataset is too short to determine types or periods. V3 and V5 showed rapid oscillations with full amplitudes of a few tens of mmag. The periods and period ratios (V3: f1/f2 = 0.81, V5: f1/f2 = 0.94) suggest low-order radial overtone (V3) and non-radial (V5) δ Scuti-type pulsations for the two stars. We also discovered an Algol-type eclipse for V4. The most interesting variable star is V6. We observed well-defined minima and steady oscillations outside eclipses with amplitude and cycle length characteristic of δ Sct pulsation. With these properties V6 seems to be an eclipsing binary with at least one pulsating component. The period analysis resulted in Porb = 1.17320(3) d. The oscillations outside eclipses seemed to be stable, with a period of Ppul = 0.12936(24) d. An interesting result is that Porb/Ppul = 9.07±0.02, suggesting that there might be a 1:9 resonance between the orbital motion and pulsation. A low-resolution optical spectrum is consistent with an F-type star, so that the oscillations may be attributed to δ Sct pulsation. From the astrometric study its cluster membership can be excluded; it is a foreground object.","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125286937","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":"The ENEAS Portal","authors":"E. Solano","doi":"10.1553/CIA143S10","DOIUrl":"https://doi.org/10.1553/CIA143S10","url":null,"abstract":"","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121751040","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 five-month multitechnique, multisite campaign on the Beta Cephei star Nu Eridani","authors":"G. Handler, C. Aerts","doi":"10.1553/CIA142S20","DOIUrl":"https://doi.org/10.1553/CIA142S20","url":null,"abstract":"We have organised the largest ever observing campaign for a β Cephei star. Its target star is ν Eridani. We briefly discuss the prospects and problems for asteroseismology of B-type main sequence pulsators and we describe the layout of the campaign based on our scientific goals. Finally, we invite all interested colleagues who have not already done so to join our team.","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129882345","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":"Multiperiodicity of V350 Peg","authors":"J. Vidal-Sainz, P. Wils, P. Lampens, E. García‐Melendo","doi":"10.1553/CIA142S52","DOIUrl":"https://doi.org/10.1553/CIA142S52","url":null,"abstract":"We report on the variability of V350 Peg, a δ Scuti star newly discovered by Hipparcos. Based on observations acquired during 35 nights at two private observatories in Spain, we could show that this star pulsates in a close doublet of frequencies (∆ f/f=3%). The period as listed in the Hipparcos Catalogue is not confirmed. V350 Peg (= HIP 115563) is a small-amplitude variable star assigned to the δ Scuti class of pulsating stars with a period of 0.2012 days and a total amplitude of 0.05 mag (ESA 1997). During 35 nights between July 1997 and December 2001 some 7500 CCD differential observations in the V band were acquired at the Monegrillo and Esteve Duran observatories in Northern Spain. HD 220538 (= HIP 115545) served as a comparison star. A Fourier analysis of the new data revealed two significant frequencies separated by 0.17 c/d and with very similar amplitudes: one at 5.840 c/d (0.1712 d; semi-amp. 27 mmag) and one at 5.668 c/d (0.1764 d; semi-amp. 24 mmag). The result is an obvious beat phenomenon with a period of 5.81 days. But a fit with only two frequencies explains only half of the total variation (Fig. 1). The ratio of the most dominant frequencies (f2/f1 = 0.97) indicates non-radial pulsation for at least one of the modes. More frequencies are obviously excited. Though we have been searching for them, we cannot be confident about their correct identification due to various kinds of aliasing effects. The detailed analJ. Vidal-Sainz, P. Wils, P. Lampens, and E. Garcia-Melendo 53 ysis will soon be available (Vidal-Sainz et al. 2002). The multiperiodicity combined with the short beat period and the fact that several non-radial modes are possibly excited, make this star a worthwhile target for a follow-up study in the context of a multisite campaign. -0.95","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131561782","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":"Multiple frequencies of Theta 2 Tau: Comparison of ground-based and space measurements","authors":"M. Breger, Renate Zechner, Don Kurtz, Jaymie Matthews, E. Poretti, M. Breger","doi":"10.1553/CIA141S4","DOIUrl":"https://doi.org/10.1553/CIA141S4","url":null,"abstract":"The satellite photometry of the ‐ Scuti star µ 2 Tau obtained with the WideField Infrared Explorer (WIRE) led to the detection of 12 frequencies of pulsation (Poretti et al. 2002). We examine the available ground-based photometry in the literature to check whether these frequencies are also present. The re-analysis of the 1986 Delta Scuti Network data leads to 10 statistically signiflcant frequencies (amplitude signal/noise ratio greater than 4.0). 9 of these 10 frequencies are in excellent agreement with those detected from space, while the 10th frequency is seen as a peak in the WIRE residuals, though not at a statistically signiflcant level. Previous reports on amplitude variability are conflrmed.","PeriodicalId":151133,"journal":{"name":"Third Coast","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117161943","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}