- ID:
- ivo://CDS.VizieR/J/A+A/578/A25
- Title:
- Light curves for the eclipsing binary V1094 Tau
- Short Name:
- J/A+A/578/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V1094 Tau is a bright eclipsing binary star with an orbital period close to 9 days containing two stars similar to the Sun. Our aim is to test models of Sun-like stars using precise and accurate mass and radius measurements for both stars in V1094 Tau. We present new spectroscopy of V1094 Tau which we use to estimate the effective temperatures of both stars and to refine their spectroscopic orbits. We also present new, high-quality photometry covering both eclipses of V1094 Tau in the Stroemgren uvby system and in the Johnson V-band. The masses, radii and effective temperatures of the stars in V1094 Tau are found to be M_A_=1.0965+/-0.0040M_{sun}_, R_A_=1.4109+/-0.0058R_{sun}_, T_eff,A_=5850+/-100K, and M_B_=1.0120+/-0.0028M_{sun}_, R_B_=1.1063+/-0.0066R_{sun}_, T_eff,B_=5700+/-100K. An analysis of the times of mid-eclipse and the radial velocity data reveals apsidal motion with a period of 14500+/-3700-years. The observed masses, radii and effective temperatures are consistent with stellar models for an age ~6Gyr if the stars are assumed to have a metallicity similar to the Sun. This estimate is in reasonable agreement with our estimate of the metallicity derived using Stroemgren photometry and treating the binary as a single star ([Fe/H]=-0.09+/-0.11). The rotation velocities of the stars suggest that V1094 Tau is close to the limit at which tidal interactions between the stars force them to rotate pseudo-syncronously with the orbital motion.
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- ID:
- ivo://CDS.VizieR/J/A+A/551/A2
- Title:
- Light curves of DP CVn and DI Psc
- Short Name:
- J/A+A/551/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first Doppler imaging study of the two rapidly rotating, single K-giants DP CVn and DI Psc in order to study the surface spot configuration and to pinpoint their stellar evolutionary status. Optical spectroscopy and photometry are used to determine the fundamental astrophysical properties. Doppler imaging is applied to recover the surface temperature distribution for both stars, while photometric light-curve inversions are carried out for studying the long-term changes of the surface activity of DP CVn. Surface differential rotation of DP CVn is estimated from cross-correlating the available subsequent Doppler reconstructions separated by roughly one rotation period. Both stars appear to have higher than normal lithium abundance, LTE logn of 2.28 (DP CVn) and 2.20 (DI Psc), and are supposed to be located at the end of the first Li dredge-up on the RGB. Photometric observations reveal rotational modulation with a period of 14.010d (DP CVn) and 18.066d (DI Psc). Doppler reconstructions from the available mapping lines well agree in the revealed spot patterns, recovering rather low latitude spots for both stars with temperature contrasts of {DELTA}T~600-800K below the unspotted photospheric background. Spots at higher latitudes are also found but either with less contrast (DP CVn) or with smaller extent (DI Psc). A preliminary antisolar-type differential rotation with {alpha}=-0.035 is found for DP CVn from cross-correlating the subsequent Doppler images. Long-term photometric analysis supports the existence of active longitudes, as well as the differential rotation.
- ID:
- ivo://CDS.VizieR/J/A+A/524/A86
- Title:
- Light curves of SDSS J003941.06+005427.5
- Short Name:
- J/A+A/524/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VLT spectroscopy and NTT photometry of the faint cataclysmic binary SDSS J003941.06+005427.5. This object shows triple-peaked H{alpha} emission with all three peaks variable in both strength and velocity. We measure an orbital period of 91.395+/-0.093min from the velocity variations of the wings of the Halpha emission line. Using the GALEX and SDSS photometry of this object, we determine a white dwarf temperature of 15000K and a very late (>=L2) spectral type for the companion star. These measurements, plus the relatively long orbital period, suggest that SDSS J003941.06+005427.5 may be a post-bounce cataclysmic variable. Doppler maps of the H{alpha} and HeI 6678{AA} emission features show an accretion disc with a non-uniform brightness and departures from Keplerian flow. The third emission peak is detected only in H{alpha} and at a relatively low velocity amplitude of 202+/-3km/s. We are unable to explain this emission as arising from either the white dwarf, the secondary star, or the accretion disc. We tentatively attribute this mysterious central peak to a coronal loop anchored at the secondary star. If confirmed, this would be the first example of a slingshot prominence in a CV with a low mass-transfer rate and/or a fully convective secondary star.
- ID:
- ivo://CDS.VizieR/J/A+A/507/929
- Title:
- Light curves of SDSS J100658.40+233724.4
- Short Name:
- J/A+A/507/929
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-resolved spectroscopy and photometry of SDSS J100658.40+233724.4, which we have discovered to be an eclipsing cataclysmic variable with an orbital period of 0.18591324 days (267.71507min). The observed velocity amplitude of the secondary star is 276+/-7km/s, which an irradiation correction reduces to 258+/-12km/s. Doppler tomography of emission lines from the infrared calcium triplet supports this measurement. We have modelled the light curve using the LCURVE code and Markov Chain Monte Carlo simulations, finding a mass ratio of 0.51+/-0.08. From the velocity amplitude and the light curve analysis we find the mass of the white dwarf to be 0.78+/-0.12M_{sun}_ and the masses and radii of the secondary star to be 0.40+/-0.10M_{sun}_ and 0.466+/-0.036R_{sun}_, respectively. The secondary component is less dense than a normal main sequence star but its properties are in good agreement with the expected values for a CV of this orbital period. By modelling the spectral energy distribution of the system we find a distance of 676+/-40pc and estimate a white dwarf effective temperature of 16500+/-2000K.
- ID:
- ivo://CDS.VizieR/J/AJ/156/6
- Title:
- Light element abundances of RGB & AGB stars in M10
- Short Name:
- J/AJ/156/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CN and CH band measurements for 137 red giant branch (RGB) and asymptotic giant branch (AGB) stars in the Galactic globular cluster M10. Our measurements come from low-resolution spectroscopy taken with the Hydra spectrograph on the WIYN-3.5 m telescope. We use these measurements to identify two populations of stars within the cluster, CN-normal and CN-enhanced, and find that in our sample 60% of stars are CN-enhanced. Our large sample allows us to conduct a detailed analysis on the carbon and nitrogen abundances and the radial distribution of each population separately. Our analysis of the radial dependence shows that each population has the same radial distribution in the cluster, which is likely due to the cluster being dynamically evolved. We also compare our results to other methods of classifying multiple populations in globular clusters such as the Na-O anti-correlation and the HST pseudo-color-magnitude diagrams. We find that these three methods of identifying multiple populations are in good agreement with each other for M10 and all lead to an estimate of the fraction of second-generation stars approximately equal to 60%. Among AGB stars, when classified by the CN band, there appears to be a lack of second-generation stars when compared to the RGB stars. However, when classified by [N/Fe], we find a similar 60% of AGB stars in the second generation. Finally, we use the measured carbon and nitrogen abundances in RGB stars to study the change of each element with magnitude as stars evolve up the RGB, comparing the results to globular clusters of similar metallicity, M3 and M13.
- ID:
- ivo://CDS.VizieR/J/A+A/628/A111
- Title:
- Li in BPS CS22876-032 spectrum
- Short Name:
- J/A+A/628/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution and high-quality UVES spectroscopic data of the metal-poor double-lined spectroscopic binary CS 22876-032 ([Fe/H] approximately -3.7dex). Our goal is to derive the ^6^Li/^7^Li isotopic ratio by analysing the LiI 670.8nm doublet. Methods. We co-added all 28 useful spectra normalised and corrected for radial velocity to the rest frame of the primary star. We fitted the Li profile with a grid of the 3D non-local thermodynamic equilibrium (NLTE) synthetic spectra to take into account the line profile asymmetries induced by stellar convection, and performed Monte Carlo simulations to evaluate the uncertainty of the fit of the Li line profile. We checked that the veiling factor does not affect the derived isotopic ratio, ^6^Li/^7^Li, and only modifies the Li abundance, A(Li), by about 0.15dex. The best fit of the Li profile of the primary star provides A(Li)=2.17+/-0.01dex and ^6^Li/^7^Li=8^+2^_-5_% at 68% confidence level. In addition, we improved the Li abundance of the secondary star at A(Li)=1.55+/-0.04dex, which is about 0.6 dex lower than that of the primary star. The analysis of the Li profile of the primary star is consistent with no detection of ^6^Li and provides an upper limit to the isotopic ratio of ^6^Li/^7^Li<10% at this very low metallicity, about 0.5dex lower in metallicity than previous attempts for detection of ^6^Li in extremely metal poor stars. These results do not solve or worsen the cosmological ^7^Li problem, nor do they support the need for non-standard ^6^Li production in the early Universe.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A25
- Title:
- Linear and circular polarisation spectra of 2 stars
- Short Name:
- J/A+A/531/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The identification of the carriers of diffuse interstellar bands (DIBs) remains one of the long-standing mysteries in astronomy. The detection of a polarisation signal in a DIB profile can be used to distinguish between a dust or gas-phase carrier. The polarisation profile can give additional information on the grain or molecular properties of the absorber. The aim is to measure the polarisation efficiency of the carriers of the diffuse interstellar bands.
- ID:
- ivo://CDS.VizieR/J/A+A/459/317
- Title:
- Line Frequencies for Uracil
- Short Name:
- J/A+A/459/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new laboratory spectroscopic data on the nucleic acid uracil. The dataset has been extended both into the microwave and towards mm-wavelengths with the aim to provide accurate transition rest frequencies for astrophysical searches. The complete experimental linelist used for the analysis of the data is compiled in Table 2. Lines marked with an asterisk are taken from Brown et al. (1988, J. Mol. Struct. 190, 185 and J. Am. Chem. Soc. 110, 2329), all other lines have been measured in this work.
- ID:
- ivo://CDS.VizieR/J/A+A/408/L29
- Title:
- Line identification of HD 34700
- Short Name:
- J/A+A/408/L29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We announce the star HD 34700 to be a double-lined spectroscopic binary, and find it to be a weak-line T Tauri object. The spectra of both components are very similar and both show the Li I feature at 6708{AA}. Strong arguments in favour of the binary nature of the star as opposed to other possibilities are offered. It is very likely that the companion is also a T Tauri star of similar mass. We present, in Table 2, a list of the lines identified and the radial velocities of the two components for three epochs.
- ID:
- ivo://CDS.VizieR/J/A+AS/103/83
- Title:
- Line identifications in a fireball spectrum
- Short Name:
- J/A+AS/103/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 305 emission lines were found in a spectrum of a fireball of -9th magnitude. The identification of most of the lines is given. Also a detailed tracing of the spectrum in the range 3600-6600{AA} is presented. The tracing contains also computed synthetic spectrum and both spectra can be easily compared. The following species were found in the spectrum: Fe I, Na I, Mg I, Al I, Ca I, Ti I, Cr I, Mn I, Ni I, Mg II, Si II, Ca II, Fe II, FeO, probably also Si I, Ba II, C_2_, and possibly V I, Co I, Cu I, Ti II. The presence of other chemical elements in meteor spectra is discussed.
