- ID:
- ivo://CDS.VizieR/J/MNRAS/372/1804
- Title:
- Magnetic fields of chem. peculiar stars
- Short Name:
- J/MNRAS/372/1804
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectropolarimetric observations of 96 chemically peculiar (CP) main-sequence stars have been carried out at the 6-m telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) with the aim of searching for the presence of stellar magnetic fields. The stars selected for investigation were CP stars known to have strong anomalies in the wavelength region of the continuum flux depression around {lambda} 5200{AA}. This selection was conducted with the aid of low-resolution spectral observations, made with the SAO RAS 1-m telescope, and of published differential photometric data. Magnetic fields have been successfully detected in 72 stars of which only three stars were previously known to have magnetic fields. For two stars, the longitudinal component of the magnetic field B_e_exceeds 5kG: HD178892 - 7.4kG, and HD258686 - 6.7kG. We failed to reliably detect the magnetic field in the other 24 CP stars. These stars are mostly fast rotators, a feature which hampers accurate measurements of B_e_. It is demonstrated in this paper that selecting candidate magnetic stars by considering their photometric indices Z or {Delta}alpha}, or alternatively, by inspecting low-resolution spectra around the {lambda}5200{AA} flux depression, considerably increases the detection rate.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/AstBu/75.294
- Title:
- Magnetic fields of CP stars (2012)
- Short Name:
- J/other/AstBu/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of measuring longitudinal magnetic fields (Be), rotation velocities (v_esini), and radial velocities (VR) of 163 stars observed with the Main Stellar Spectrograph (MSS) of the 6-m BTA telescope of the Special Astrophysical Observatory in 2012. Observations of standard stars without magnetic fields confirm the absence of systematic errors capable of introducing distortions into the longitudinal-field measurement results.
- ID:
- ivo://CDS.VizieR/J/PAZh/31/437
- Title:
- Magnetic peculiar stars elemental abundances
- Short Name:
- J/PAZh/31/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Temperature dependance of the abundances of the chemical elements Si, Ca, Cr and Fe in the atmospheres of normal, metallic-line (Am), magnetic peculiar (Ap) and pulsating magnetic peculiar (r0Ap) stars in the range 6000-15000K.
- ID:
- ivo://CDS.VizieR/J/other/AstBu/74.66
- Title:
- Main sequence magnetic stars properties
- Short Name:
- J/other/AstBu/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We reconsidered the previous studies of properties of magnetic stars based on the latest data on average surface magnetic fields of 177 stars. New, corrected results have been obtained that allow a better understanding of the phenomenon of magnetic chemically peculiar stars.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A40
- Title:
- 1002 mCP stars from LAMOST DR4
- Short Name:
- J/A+A/640/A40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present work is aimed at identifying new mCP stars using spectra collected by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Suitable candidates were selected by searching LAMOST DR4 spectra for the presence of the characteristic 5200{AA} flux depression. Spectral classification was carried out with a modified version of the MKCLASS code and the accuracy of the classifications was estimated by comparison with results from manual classification and the literature. Using parallax data and photometry from Gaia DR2, we investigated the space distribution of our sample stars and their properties in the colour-magnitude diagram. Our final sample consists of 1002 mCP stars, most of which are new discoveries (only 59 common entries with the Catalogue of Ap, HgMn and Am stars). Traditional mCP star peculiarities have been identified in all but 36 stars, highlighting the efficiency of the code's peculiarity identification capabilities. The derived temperature and peculiarity types are in agreement with manually derived classifications and the literature. Our sample stars are between 100Myr and 1Gyr old, with the majority having masses between 2M_{sun}_ and 3M_{sun}_. Our results could be considered as strong evidence for an inhomogeneous age distribution among low-mass (M<3M_{sun}_) mCP stars; however, we caution that our sample has not been selected on the basis of an unbiased, direct detection of a magnetic field. We identified several astrophysically interesting objects: the mCP stars LAMOST J122746.05+113635.3 and LAMOST J150331.87+093125.4 have distances and kinematical properties in agreement with halo stars; LAMOST J034306.74+495240.7 is an eclipsing binary system (Porb=5.1435+/-0.0012d) hosting an mCP star component; and LAMOST J050146.85+383500.8 was found to be an SB2 system likely comprising of an mCP star and a supergiant component. With our work, we significantly increase the sample size of known Galactic mCP stars, paving the way for future in-depth statistical studies.
- ID:
- ivo://CDS.VizieR/J/other/RAA/15.1182
- Title:
- M Dwarf catalog of LAMOST DR1
- Short Name:
- J/other/RAA/15.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic catalog of 93 619 M dwarfs from the first data release of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) general survey. During sample selection, M giant contamination was eliminated using 2MASS photometry and CaH/TiO molecular indices. For each spectrum, the spectral subtype and values are provided including radial velocity, H{alpha} equivalent width, a series of prominent molecular band indices, and the metal-sensitive parameter {zeta}, as well as distances and the space motions for high S/N objects. In addition, H{alpha} emission lines are measured to examine the magnetic activity properties of M dwarfs and 7179 active ones are found. In particular, a subsample with significant variation in magnetic activity is revealed through observations from different epochs. Finally, statistical analysis for this sample is performed, including the metallicity classification, the distribution of molecular band indices and their errors.
- ID:
- ivo://CDS.VizieR/J/A+A/455/303
- Title:
- Nainital-Cape Survey. II. Null results
- Short Name:
- J/A+A/455/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We search for photometric variability in chemically peculiar A type stars in the northern hemisphere. High-speed photometric observations of Ap and Am star candidates have been carried out from ARIES (Manora Peak, Nainital) using a three-channel fast photometer attached to the ARIES 104-cm Sampurnanand telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A116
- Title:
- Nainital-Cape Survey. IV.
- Short Name:
- J/A+A/590/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Nainital-Cape Survey is a dedicated ongoing Survey programme to search for and study pulsational variability in chemically peculiar (CP) stars to understand their internal structure and evolution. The main aims of this Survey are to find new pulsating Ap and Am stars in the northern and southern hemisphere and to perform asteroseismic studies of these new pulsators. The Survey is conducted using high-speed photometry. The candidate stars were selected on the basis of having Stromgren photometric indices similar to those of known pulsating CP stars. Over the last decade a total of 337 candidate pulsating CP stars were observed for the Nainital-Cape Survey, making it one of the longest ground-based surveys for pulsation in CP stars in terms of time span and sample size. The previous papers of this series presented seven new pulsating variables and 229 null results. In this paper we present the light curves, frequency spectra and various astrophysical parameters of the 108 additional CP stars observed since the last reported results. We also tabulated the basic physical parameters of the known roAp stars. As a part of establishing the detection limits in the Nainital-Cape Survey, we investigated the scintillation noise level at the two observing sites used in this Survey, Sutherland and Nainital, by comparing the combined frequency spectra stars observed from each location. Our analysis shows that both the sites permit the detection of variations of the order of 0.6-milli-magnitude (mmag) in the frequency range 1-4mHz, Sutherland is on average marginally better.
- ID:
- ivo://CDS.VizieR/J/AJ/152/104
- Title:
- New photometrically variable magnetic CP stars
- Short Name:
- J/AJ/152/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The magnetic Ap or CP2 stars are natural atomic and magnetic laboratories. Strictly periodic changes are observed in the spectra and brightness of these stars, which allow the derivation of rotational periods. Related to this group of objects are the He-weak (CP4) and He-rich stars, some of which also undergo brightness changes due to rotational modulation. Increasing the sample size of known rotational periods among CP2/4 stars is important and will contribute to our understanding of these objects and their evolution in time. We have compiled an extensive target list of CP2/4 stars from the General Catalog of Ap, HgMn, and Am stars, including several early-type (spectral types B/A) variables of undetermined type from the International Variable Star Index. We investigated our sample stars using publicly available observations from the ASAS-3 archive. Our previous efforts in this respect led to the discovery of 323 variable stars. Using a refined analysis approach, we were able to identify another 360 stars exhibiting photometric variability in ASAS-3 data. Summary data, folded light curves and, if available, information from the literature are presented for our final sample, which is composed of 334 bona-fide {alpha}^2^ Canum Venaticorum (ACV) variables, 23 ACV candidates, and 3 eclipsing binary systems. Interesting and unusual objects are discussed in detail. In particular, we call attention to HD66051 (V414 Pup), which is an eclipsing binary system showing obvious rotational modulation of the light curve due to the presence of an ACV variable in the system.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A14
- Title:
- New R Coronae Borealis stars
- Short Name:
- J/A+A/635/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains 2356 entries. It was created to list targets of interest that have similar near- and mid-infrared characteristics than R Coronae Borealis (RCB) stars which are hydrogen-deficient carbon-rich supergiant stars known to possess warm circumstellar shells. It is therefore a catalogue enriched in such objects and further spectroscopic follow-ups are needed to reveal the true nature of each target. The catalogue was produced from a series of selection criteria on the infrared colours and brightness of sources published in the WISE All-Sky data release, and also listed in the 2MASS catalogue. These sources spread over the entire sky. The selection criteria are described in section 2 of the paper.
