- ID:
- ivo://CDS.VizieR/J/ApJ/898/47
- Title:
- Fe/H & radii from blended sp. of simulated binaries
- Short Name:
- J/ApJ/898/47
- Date:
- 13 Dec 2021 08:45:04
- Publisher:
- CDS
- Description:
- In this work, we quantify the effect of an unresolved companion star on the derived stellar parameters of the primary star if a blended spectrum is fit assuming the star is single. Fitting tools that determine stellar parameters from spectra typically fit for a single star, but we know that up to half of all exoplanet host stars may have one or more companion stars. We use high- resolution spectra of planet host stars in the Kepler field from the California-Kepler Survey to create simulated binaries; we select eight stellar pairs and vary the contribution of the secondary star, then determine stellar parameters with SpecMatch-Emp and compare them to the parameters derived for the primary star alone. We find that, in most cases, the effective temperature, surface gravity, metallicity, and stellar radius derived from the composite spectrum are within 2-3{sigma} of the values determined from the unblended spectrum, but the deviations depend on the properties of the two stars. Relatively bright companion stars that are similar to the primary star have the largest effect on the derived parameters; in these cases, the stellar radii can be overestimated by up to 60%. We find that metallicities are generally underestimated, with values up to eight times smaller than the typical uncertainty in [Fe/H]. Our study shows that follow-up observations are necessary to detect or set limits on stellar companions of planetary host stars so that stellar (and planet) parameters are as accurate as possible.
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Search Results
- ID:
- ivo://CDS.VizieR/V/58
- Title:
- [Fe/H], Vel, Orbits of F2-K5 Dwarfs 80pc from Sun
- Short Name:
- V/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this catalog, metallicities, distances, components of space velocities and parameters of osculating orbits are calculated for 1065 F2-K5 dwarfs with UBV photometric data, proper motions and radial velocities. The present sample is composed on the base of the Ochsenbein (1980) catalogue and contains the stars of the V (IV-V) luminosity class, within the colour range 0.35<B-V<1.10 (which corresponds to the spectral class range F2-K5). Sandage's (1969) Hyades sequence was used to determine the value delta (U-B) for each star. The authors calibrated the ultraviolet excess in terms of [Fe/H] separately for the four of the temperature index (B-V) where delta(U-B) practically does not depend on the effective temperature. Intervals in (B-V) correspond to the following division on spectral class intervals: F2-F9, G0-G4, and G5-G9, K0-K5. Metallicity is calculated from the formulae: [Fe/H]=-5.3*delta(U-B)+0.02 for stars F2-F9 [Fe/H]=-5.1*delta(U-B)+0.13 for stars G0-G4 [Fe/H]=-5.4*delta(U-B)+0.02 for stars G5-G9 [Fe/H]=-4.7*delta(U-B)-0.04 for stars K0-K5 These relations follow from the assumption that mean metallicity and metallicity dispersion for stars of all spectral classes are the same. Distances to the stars were calculated from spectral parallaxes. Absolute magnitudes (M(V)) were obtained from the Sp,M(V)-relation for dwarfs (Straizys, 1982). The sample includes only stars nearer than 80 pc because reddening is negligible for them. The obtained distances together with radial velocities and proper motions are used to calculate the components of space velocities. The eccentricities, apogalactic and perigalactic distances of the stars were calculated from the osculating orbit approximation according to the galaxy model from the paper by Eggen et al. (1962).
- ID:
- ivo://CDS.VizieR/J/ApJS/189/15
- Title:
- FeII emission in a sample of AGN spectra
- Short Name:
- J/ApJS/189/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of optical FeII emission in 302 active galactic nuclei (AGNs) selected from the Sloan Digital Sky Survey. We group the strongest FeII multiplets into three groups according to the lower term of the transition (b^4^F, a^6^S, and a^4^G terms). These approximately correspond to the blue, central, and red parts, respectively, of the "iron shelf" around H{beta}. We calculate an FeII template that takes into account transitions into these three terms and an additional group of lines, based on a reconstruction of the spectrum of I Zw 1. This FeII template gives a more precise fit of the FeII lines in broad-line AGNs than other templates. We extract FeII, H{alpha}, H{beta}, [OIII], and [NII] emission parameters and investigate correlations between them. We find that FeII lines probably originate in an intermediate line region. We note that the blue, red, and central parts of the iron shelf have different relative intensities in different objects. Their ratios depend on continuum luminosity, FWHM H{beta}, the velocity shift of FeII, and the H{alpha}/H{beta} flux ratio. We examine the dependence of the well-known anti-correlation between the equivalent widths of FeII and [OIII] on continuum luminosity. We find that there is a Baldwin effect for [OIII] but an inverse Baldwin effect for the FeII emission. The [OIII]/FeII ratio thus decreases with L_{lambda}5100_. Since the ratio is a major component of the Boroson & Green Eigenvector 1 (EV1), this implies a connection between the Baldwin effect and EV1 and could be connected with AGN evolution. We find that spectra are different for H{beta} FWHMs greater and less than ~3000km/s, and that there are different correlation coefficients between the parameters.
6144. FeII emission in quasars
- ID:
- ivo://CDS.VizieR/J/ApJ/687/78
- Title:
- FeII emission in quasars
- Short Name:
- J/ApJ/687/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Broad FeII emission is a prominent feature of the optical and ultraviolet spectra of quasars. We report on a systematical investigation of optical FeII emission in a large sample of 4037 z<0.8 quasars selected from the SDSS-DR5 quasar catalog (Cat. VII/252). We have developed and tested a detailed line-fitting technique, taking into account the complex continuum and narrow and broad emission-line spectra. Our primary goal is to quantify the velocity broadening and velocity shift of the FeII spectrum in order to constrain the location of the FeII-emitting region and its relation to the broad-line region. We find that the majority of quasars show FeII emission that is redshifted, typically by ~400km/s, but up to 2000km/s, with respect to the systemic velocity of the narrow-line region or of the conventional broad-line region as traced by the H{beta} line. Moreover, the line width of FeII is significantly narrower than that of the broad component of H{beta}. We show that the magnitude of the FeII redshift correlates inversely with the Eddington ratio, and that there is a tendency for sources with redshifted FeII emission to show red asymmetry in the H{beta} line. These characteristics strongly suggest that FeII originates from a location different from, and most likely exterior to, the region that produces most of H{beta}. The FeII-emitting zone traces a portion of the broad-line region of intermediate velocities whose dynamics may be dominated by infall.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/86
- Title:
- FeII emission in SDSS type 1 AGNs
- Short Name:
- J/ApJ/736/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used a large, homogeneous sample of 4178 z<=0.8 Seyfert 1 galaxies and QSOs selected from the Sloan Digital Sky Survey to investigate the strength of FeII emission and its correlation with other emission lines and physical parameters of active galactic nuclei. We find that the strongest correlations of almost all the emission-line intensity ratios and equivalent widths (EWs) are with the Eddington ratio (L/L_Edd_), rather than with the continuum luminosity at 5100{AA} (L_5100_) or black hole mass (M_BH_); the only exception is the EW of ultraviolet FeII emission, which does not correlate at all with broad-line width, L_5100_, M_BH_, or L/L_Edd_. By contrast, the intensity ratios of both the ultraviolet and optical FeII emission to MgII{lambda}2800 correlate quite strongly with L/L_Edd_. Interestingly, among all the emission lines in the near-UV and optical studied in this paper (including MgII{lambda}2800, H{beta}, and [OIII]{lambda}5007), the EW of narrow optical FeII emission has the strongest correlation with L/L_Edd_. We hypothesize that the variation of the emission-line strength in active galaxies is regulated by L/L_Edd_ because it governs the global distribution of the hydrogen column density of the clouds gravitationally bound in the line-emitting region, as well as its overall gas supply. The systematic dependence on L/L_Edd_ must be corrected when using the FeII/MgII intensity ratio as a measure of the Fe/Mg abundance ratio to study the history of chemical evolution in QSO environments.
- ID:
- ivo://CDS.VizieR/J/A+A/381/507
- Title:
- Fe II emission lines of RR Tel
- Short Name:
- J/A+A/381/507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Files table1.dat and table2.dat contain the permitted and forbidden Fe II emission lines respectively which have been selected from the optical spectrum of RR Tel between 3180 and 9455{AA}. The spectrum was observed by Crawford et al. (1999, Cat. <J/A+AS/139/135>) whose corrected line fluxes and velocity widths we took for further analysis in this work. In the tables there are also values characteristic for the corresponding multiplets and lines such as multiplet numbers, term designations, level excitation potentials and quantum numbers J. The log functions of gf's, line fluxes and wavelengths are relevant for the SAC curves.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A57
- Title:
- FeII-FeVIII K lines Plasma environment effects
- Short Name:
- J/A+A/643/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the framework of compact-object accretion disks, we have calculated plasma environment effects on the atomic structure and decay parameters used in the modeling of the K lines in lowly charged iron ions, namely FeII-FeVIII. We use the fully relativistic multiconfiguration Dirac-Fock (MCDF) method approximating the plasma electron-nucleus and electron-electron screenings with a time-averaged Debye-Huckel potential. Results. Modified ionization potentials, K-threshold energies, wavelengths, radiative emission rates, and Auger widths are reported for plasmas characterized by electron temperatures and densities in the ranges 10^5^-10^7^K and 10^18^-10^22^cm^-3^. In addition, we propose two universal fitting formulae to predict the IP and K-thresold lowerings in any elemental ion. We conclude that the high-resolution X-ray spectrometers onboard the future XRISM and ATHENA space missions will be able to detect the lowering of the K edges of these Fe ions due to the extreme plasma conditions occurring in accretion disks around compact objects.
- ID:
- ivo://CDS.VizieR/J/A+A/536/A74
- Title:
- FeII forbidden lines radiative transition rates
- Short Name:
- J/A+A/536/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report electric quadrupole and magnetic dipole transitions among the levels belonging to 3d^6^4s, 3d^7^ and 3d^5^4s^2^ configurations of Fe II in a large scale configuration interaction (CI) calculation. The CIV3 code developed by Hibbert and coworkers is used to determine configuration interaction wave functions for these levels: for the optimisation of two different sets of orbitals based on alternative choices of the 3d function, for creating and diagonalising the Hamiltonian matrices and finally for calculating transition probabilities.
6149. Fe I in metal-poor stars
- ID:
- ivo://CDS.VizieR/J/A+A/305/245
- Title:
- Fe I in metal-poor stars
- Short Name:
- J/A+A/305/245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A detailed analysis of neutral iron lines in a sample of 13 metal-poor dwarfs and subgiants is carried out on the basis of high resolution spectra obtained with the ESO Coude Echelle Spectrometer. The deduced iron abundance is found to depend on the excitation potential of the line used, higher excitation lines generally indicating higher abundances. This could be caused by departures from the local thermodynamic equilibrium (LTE) or by temperature inhomogeneities in the stellar atmospheres. The dependency of this effect on the stellar atmospheric parameters is investigated. From the comparison of iron lines with lines of other elements, it is concluded that the low excitation Fe I lines are much more affected than the high excitation lines. The consequences of these effects for the classical abundance analyses are examined. It is found that they may explain, at least in part, some previously reported discrepancies between the results of different authors.
- ID:
- ivo://CDS.VizieR/J/A+A/340/300
- Title:
- Fe II oscillator strengths
- Short Name:
- J/A+A/340/300
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of the agreement between experiment (recent experimental log(gf) values) and our method (orthogonal operator technique) is shown in table 1. The experimental data are taken from the critical compilation by Giridhar and Ferro (1995RMxAA..31...23G) using data from Kroll and Kock (1987A&AS...67..225K), and from most recent data by Bergeson et al. (1996ApJ...464.1044B). Eight lines in this table are indicated by * in front of the orthogonal log(gf) value: for these lines the difference between experimental value and our calculated value is >=0.2.