- ID:
- ivo://CDS.VizieR/J/A+AS/133/299
- Title:
- Long-term spectroscopy of eta Carinae
- Short Name:
- J/A+AS/133/299
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This Table contains parameters of 655 spectral features in the spectrum of eta Carinae, in the wavelength region 3850-11000 Angstrom. The narrow and broad line components were measured separately, for the spectrum in high excitation state (year 1995) and during the "spectroscopic event" of June/1992. The spectra were collected at ESO (Chile) and LNA (Brazil) at high resolution. Several spectral lines of Fe II, [Fe II], [Fe III], [N II] ands Ca II are identifyed for the first time in the spectrum of this star. Line variability between high and low excitation states is characterized in an objective way (parameter var in the last column).
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- ID:
- ivo://CDS.VizieR/J/A+A/419/607
- Title:
- Long-term variations of kappa Dra
- Short Name:
- J/A+A/419/607
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A summary of results of spectroscopic monitoring of the bright Be star kappa Dra carried out at the Ondrejov Observatory between 1990 and 2004 is presented. To investigate long-term variations of Kappa Dra, we focused on H{alpha}, H{beta}, H{gamma}, H{delta}, SiII 6347{AA}, SiII 6371{AA}, HeI 6678{AA}, and FeII 6456{AA} lines. We measured equivalent widths {W}, peak intensities of the double emission lines, and the central intensity of the absorption reversals relative to the adjacent continuum (I_V_, I_R_, and I_c_, respectively), and also the peak separation between violet and red peaks (Delta_nu_p). Note that {W} is taken with a negative sign for the emission line profile. Only {W}, and I_c_ were measured, of course, for the absorption lines of {HeI} and {SiII}. All measurements are collected together with heliocentric Julian dates of mid-exposures (HJDs) in Tables 2, 3 and 4.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/2738
- Title:
- Magnetic properties of {omega} Ori
- Short Name:
- J/MNRAS/426/2738
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One hundred and twenty-five new high-precision spectropolarimetric observations have been obtained with ESPaDOnS (Eschelle Spectro-Polarimetric Device for the Observation of Stars) at the Canada-France-Hawaii Telescope and Narval at Telescope Bernard Lyot to investigate the magnetic properties of the classical Be star omega Ori. No Stokes V signatures are detected in our polarimetric data. Measurements of the longitudinal magnetic field, with a median error bar of 30G, and direct modelling of the mean least-squares deconvolved Stokes V profiles yield no evidence for a dipole magnetic field with polar surface strength greater than ~80G.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A42
- Title:
- Main-sequence companions to massive Be stars
- Short Name:
- J/A+A/641/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- About 20% of all B-type stars are classical Be stars. The Be phenomenon is strongly correlated with rapid rotation, the origin of which remains unclear. It may be rooted in single- or binary-star evolution. In the framework of the binary channel, the initially more massive star transfers mass and angular momentum to the original secondary, which becomes a Be star. The system then evolves into a Be binary with a post-main-sequence companion, which may later be disrupted in a supernova event. Hence, if the binary channel dominates the formation of Be stars, one may expect a strong lack of close Be binaries with main sequence (MS) companions. Through an extensive, star-by-star review of the literature of a magnitude-limited sample of Galactic early-type Be stars, we investigate whether Be binaries with MS companions are known to exist. Our sample is constructed from the BeSS database and cross-matched with all available literature on the individual stars. Out of an initial list of 505 Be stars, we compile a final sample of 287 Galactic Be stars earlier than B1.5 with V<=12mag. Out of those, 13 objects were reported as Be binaries with known post-MS companions and 11 as binaries with unknown, uncertain or debated companions. We find no confirmed reports of Be binaries with MS companions. For the remaining 263 targets, no significant reports of multiplicity exist in the literature, implying that they are either Be binaries with faint companions, or truly single. The clear lack of reported MS companions to Be stars, which stands in contrast to the high number of detected B+B MS binaries, strongly supports the hypothesis that early-type Be stars are binary interaction products that spun up after mass and angular momentum transfer from a companion star. Taken at face value, our results may suggest that a large majority of the early-type Be stars have formed through binary mass-transfer.
- ID:
- ivo://CDS.VizieR/J/other/NewA/10.325
- Title:
- 2MASS observations of Be stars
- Short Name:
- J/other/NewA/10.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of almost all known Galactic Be stars in the 2MASS (<II/246>) database (1185 in total) and in the MSX (<V/114>) database (225 in total) is presented in this paper. From the color-color diagrams and spectral indexes, it is found that the IR excesses for many samples are due to free-free and free-bound emission from the ionized material around a Be star as suggested previously and that the mean spectral index derived for the samples is 1.50+/-0.34 between J to K bands and 1.14+/-0.42 between K to A bands, respectively. However, it is also found that there are eight Be stars that have large near infrared excess emission with spectral index values outside the range expected for freefree and freebound emission. This is likely attributed to circumstellar dust emission.
- ID:
- ivo://CDS.VizieR/J/A+AS/104/315
- Title:
- Member of Herbig Ae/Be stellar group
- Short Name:
- J/A+AS/104/315
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An up-to-date catalogue of Herbig Ae/Be (HAEBE) stars and related objects is listed in five tables, containing 287 objects. Table 1 contains all Ae and Be stars which historically are recognized as true HAEBE stars or potential candidate members. Table 2 gives the stars of spectral type Fe, and emission line stars with very uncertain or unknown spectral type. In Table 3 are given all known Extreme Emission Line Objects (EELOs), of which most have not been identified to belong to any specific group. Table 4a and b list other Bep or B[e] stars with strong IR-excess and unknown spectral type. Table 5 contains the non-emission line possible young objects. Furthermore, Table 6 contains 35 stars rejected from former published lists of HAEBE stars. In these tables we are including coordinates, spectral types, visual magnitudes, ranges in photometric variability and references of several key publications related to each object. Relevant remarks, such as the presence of a nebula in the vicinity of an object, are also given.
- ID:
- ivo://CDS.VizieR/J/A+A/553/A24
- Title:
- Models for rotating stars
- Short Name:
- J/A+A/553/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- B-type stars are known to rotate at various velocities, including very fast rotators near the critical velocity as the Be stars. In this paper, we provide stellar models covering the mass range between 1.7 to 15M_{sun}_, which includes the typical mass of known Be stars, at Z=0.014, 0.006 and 0.002 and for an extended range of initial velocities on the zero-age main sequence. We use the Geneva stellar-evolution code including the effects of shellular rotation and with a numerical treatment that has been improved in order for the code to track in a precise way the variation of the angular momentum content of the star as it changes under the influence of radiative winds and/or mechanical mass loss. We discuss the impact of the initial rotation rate on the tracks in the Hertzsprung-Russell diagram, the main-sequence (MS) lifetimes, the evolution of the surface rotation and abundances, as well as on the ejected masses of various isotopes. Among the new results obtained from the present grid we have that: 1) fast rotating stars with initial masses around 1.7M_{sun}_ present at the beginning of the core hydrogen-burning phase quite small convective cores with respect to their slowly rotating counterparts. This fact may be interesting to keep in mind in the frame of the asteroseismic studies of such stars; 2) the contrast between the core and surface angular velocity is higher in slower rotating stars. The values presently obtained are quite in the range of the very few values obtained for B-type stars from asteroseismology; 3) at Z=0.002, the stars in the mass range of 1.7 to 3M_{sun}_ with a mean velocity on the MS of the order of 150km/s show N/H enhancement superior to 0.2dex at mid-MS, and superior to 0.4dex at the end of the MS phase. At solar metallicity the corresponding values are below 0.2dex at any time in the MS. An extended database of stellar models containing 270 evolutionary tracks is provided to the community.
- ID:
- ivo://CDS.VizieR/J/PASP/106/949
- Title:
- Multicolor polarimetry of Be stars
- Short Name:
- J/PASP/106/949
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical polarization data in the UBVRI filter system for eight bright northern Be stars are presented here as the continuation of a long-term monitoring project begun in 1984. There are no strong cases of night-to-night variability, and the only star showing unmistakable changes in polarization from year to year over the nine years covered by the program is Pi Aquarii. Even though the observed sample spans a wide range in spectral type, vsini, and degree of intrinsic polarization, the normalized wavelength dependence of the polarization is surprisingly similar for all of the stars. Analysis of the wavelength dependence of the variable polarization of {pi} Aqr in terms of a simple equatorial-disk model suggests that changes in the circumstellar electron number density alone may be sufficient to account for the observations, but it is not clear what real physical mechanism is involved.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A136
- Title:
- MWC 922 ALMA maps and datacubes
- Short Name:
- J/A+A/629/A136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present interferometric observations with the Atacama Large Millimeter Array (ALMA) of the free-free continuum and recombination line emission at 1 and 3mm of the Red Square Nebula surrounding the B[e]-type star MWC922. The distance to the source, which is unknown, is usually taken to be d=1.7-3kpc. The unprecedented angular resolution (up to ~0.02") and exquisite sensitivity of these data reveal for the first time the structure and kinematics of the nascent compact ionized region at its center. We imaged the line emission of H30{alpha} and H39{alpha}, previously detected with single-dish observations, and of H51{epsilon}, H55{gamma}, and H63{delta}, detected for the first time in this work. The line emission is seen over a full velocity range of ~180km/s arising in a region of diameter <0.14" (less than a few hundred au) in the maser line H30{alpha}, which is the most intense transition reported here. We resolve the spatio-kinematic structure of a nearly edge-on disk rotating around a central mass of ~10M_{sun}_ (d=1.7kpc) or ~18M_{sun}_ (d=3kpc), assuming Keplerian rotation. Our data also reveal a fast (~100km/s) bipolar ejection (possibly a jet) orthogonal to the disk. In addition, a slow (<15km/s) wind may be emanating from the disk. Both, the slow and the fast winds are found to be rotating in a similar manner to the ionized layers of the disk. This represents the first empirical proof of rotation in a bipolar wind expanding at high velocity (~100km/s).
- ID:
- ivo://CDS.VizieR/J/A+AS/121/113
- Title:
- Near-IR spectra of 7 Be stars and AG Car
- Short Name:
- J/A+AS/121/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and discuss {lambda} 6470-8780 spectra of 7 poorly-studied Be stars and of one Luminous Blue Variable (AG Car), and give equivalent widths and radial velocities of selected spectral lines.
