Abundances Of Si Research Articles

Suzaku Observation of the Metallicity Distribution in the Intracluster Medium of the Fornax Cluster

Abstract The metallicity distribution in the Fornax cluster was studied with the XIS instrument on board the Suzaku satellite. The K-shell lines of O and Mg were resolved clearly, and the abundances of O, Mg, Si, S, and Fe were measured with great accuracy. The region within a $4'$ radius of NGC 1399 shows approximately solar abundances of Fe, Si, and S, while the $\mathrm{O/Fe}$ and $\mathrm{Mg/Fe}$ abundance ratios are about 0.4–0.5 and 0.7 in solar units, respectively. In the outer region of the radius range $6' < r < 23'$, the Fe and Si abundances drop to 0.4–0.5 solar and show no significant gradient within this region. The abundance ratios, $\mathrm{O/Fe}$ and $\mathrm{Mg/Fe}$, are consistent with those in the central region. We also measured the Fe abundance around NGC 1404 to be approximately solar, and the O, Ne, and Mg abundances to be 0.5–0.7 times the Fe level. A significant relative enhancement of Fe within 130 kpc of NGC 1399 and in NGC 1404 indicates an origin in SN Ia, in contrast to the species O, Ne, and Mg, which reflect the stellar metallicity. The mass-to-light ratios for O and Fe within 130 kpc of NGC 1399 are over an order of magnitude lower than those in rich clusters, reflecting the metal enrichment history of this poor cluster.

Atomic data and spectral line intensities for Si XI

Electron impact collision strengths, energy levels, oscillator strengths and spontaneous radiative decay rates are calculated for Si XI. The configurations used are 2s 2, 2s2p, 2p 2, 2l3l′, 2l4l′ and 2s5l′, with l = s,p and l′ = s,p,d giving rise to 92 fine-structure levels in intermediate coupling. Collision strengths are calculated at five incident energies (35, 70, 105, 140, and 175 Ry) in the distorted wave approximation. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates of the present work, and R-Matrix results for the 2s 2, 2s2p, 2p 2 configurations available in the literature, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10 8–10 14 cm −3 at an electron temperature of log T e(K) = 6.2, corresponding to the maximum abundance of Si XI. Spectral line intensities are calculated, and their diagnostic relevance is discussed. This dataset will be made available in the next version of the CHIANTI database.

Detailed Far‐Ultraviolet to Optical Analysis of Four [WR] Stars

We present far-UV to optical analyses of four hydrogen-deficient central stars of planetary nebulae: BD +30 3639, NGC 40, NGC 5315, and NGC 6905. Using the radiative transfer code CMFGEN, we determined new physical parameters and chemical abundances for these stars. The results were analyzed in the context of the [WR] → PG 1159 evolution via the transformed radius-temperature (RT × T*) and H-R diagrams. NGC 5315 showed itself as an odd object among the previously analyzed central stars. Its temperature (~76 kK) is considerably lower than other early-type [WR] stars (~120-150 kK). From our models for NGC 5315 and NGC 6905, it is unclear if early-type [WR] stars have smaller C/He mass ratios than other spectral classes, as claimed in the literature. A ratio of ~0.8 is found for NGC 6905. We analyzed FUSE spectra of these stars for the first time and identified phosphorus in the spectra of BD +30 3639, NGC 40, and NGC 5315 through the doublet transition P V λλ1118, 1128 (3p2Po-3s2S). The Fe, Si, P, S, and Ne abundances were analyzed in the context of the nucleosynthesis occurring in previous evolutionary phases. We found evidence for Fe deficiency in BD +30 3639 and NGC 5315, and we determined a solar Si abundance for BD +30 3639 and NGC 40. Regarding P, an oversolar abundance in the NGC 5315 model was preferred. Upper limits for the S abundance were estimated. We found that Ne is overabundant in BD +30 3639. In the other stars, Ne is weak or undetectable. Our results are in agreement with theoretical predictions and show the usefulness of [WR] stars as test beds for nucleosynthesis calculations in the AGB and post-AGB phases.

Chemical Abundances in Metal-Rich Bulge-like Stars

We have derived chemical abundances for Ca, Ti, Si, Mg, O, Na, Al, Ni, Co and Cr for a sample of stars with peculiar kinematics and probable origin near the bulge. Our sample stars are in the metallicity range = −0.8 ≤ [Fe/H] ≤ +0.6 dex, and have small pericentric distances, Rp ≤ 3.5 kpc, small scale height, with Zmax < 0.16 kpc, and old ages, 9 to 11 Gyr. We have found that the abundance distributions of O, Mg and Al lie between bulge and both thin and thick disks distributions, i. e., with an enhanced pattern relative to thin and thick disk stars, and an underabundant behavior compared to bulge stars. [Na/Fe] ratios ovelarp the bulge distribution in the metal-poor tail, and show similar values compared to thin and thick disk stars for the super-solar metallicity range. Ca, Ti and Si values are similar to those of the thick disk stars in the metal-poor range, while an underabundant behavior is seen relative to thin disk stars for metallicities [Fe/H] > +0.3 dex. Compared to bulge stars, such elements are deficient in our sample stas. For the iron-peak elements Cr and Ni we have found a slightly overabundant behavior relative to both thin and thick disks distributions in the metal-poor range, and a smooth decreasing trend for [Cr/Fe] for stars in the supersolar regime. [Co/Fe] ratios track the solar value in the metal-poor range, and show an underabundant behavior relative do thin disk stars for metallicities [Fe/H] > 0.0 dex.

Collisional Ionization Equilibrium for Optically Thin Plasmas. I. Updated Recombination Rate Coefficients for Bare through Sodium‐like Ions

Reliably interpreting spectra from electron-ionized cosmic plasmas requires accurate ionization balance calculations for the plasma in question. However, much of the atomic data needed for these calculations have not been generated using modern theoretical methods and are often highly suspect. This translates directly into the reliability of the collisional ionization equilibrium (CIE) calculations. We make use of state-of-the-art calculations of dielectronic recombination (DR) rate coefficients for the hydrogenic through Na-like ions of all elements from He up to and including Zn. Where measurements exist, these published theoretical DR data agree with recent laboratory work to within typically 35% or better at the temperatures relevant for CIE. We also make use of state-of-the-art radiative recombination (RR) rate coefficient calculations for the bare through Na-like ions of all elements from H through to Zn. Here we present improved CIE calculations for temperatures from 104 to 109 K using our data and the recommended electron impact ionization data of Mazzotta et al. for elements up to and including Ni and Mazzotta for Cu and Zn. DR and RR data for ionization stages that have not been updated are also taken from these two additional sources. We compare our calculated fractional ionic abundances using these data with those presented by Mazzotta et al. for all elements from H to Ni. The differences in peak fractional abundance are up to 60%. We also compare with the fractional ionic abundances for Mg, Si, S, Ar, Ca, Fe, and Ni derived from the modern DR calculations of Gu for the H-like through Na-like ions, and the RR calculations of Gu for the bare through F-like ions. These results are in better agreement with our work, with differences in peak fractional abundance of less than 10%.

The abundance pattern of O, Mg, Si, and Fe in the intracluster medium of the Centaurus cluster observed with XMM-Newton

The abundances of 0, Mg, Si, and Fe in the intracluster medium of the Centaurus cluster are derived. The Fe abundance has a negative radial gradient. In solar units, the Si abundance is close to the Fe abundance, while the O and Mg abundances are much lower. The high Fe/O and Si/O ratios indicate that the metal supply from supernovae la is important and that supernovae la synthesize Si as does Fe. Within 2', the O and Mg abundances are consistent with the stellar metallicity of the cD galaxy derived from the Mg 2 index. This result indicates that the central gas is dominated by the gas from the cD galaxy. The observed abundance pattern of the Centaurus cluster resembles those observed in the center of other clusters and groups of galaxies. However, the central Fe abundance and the Si/Fe ratio are 40% higher and 30% lower than those of M 87, respectively. Since the accumulation timescale of the supernovae la is greater in the Centaurus cluster, these differences imply a time dependence of nucleosynthesis by the supernovae la.

The Kinematic and Plasma Properties of X‐Ray Knots in Cassiopeia A from theChandraHETGS

We present high-resolution X-ray spectra from the young supernova remnant Cas A using a 70 ks observation taken by the Chandra High Energy Transmission Grating Spectrometer (HETGS). Line emission, dominated by Si and S ions, is used for high-resolution spectral analysis of many bright, narrow regions of Cas A to examine their kinematics and plasma state. These data allow a three-dimensional (3D) reconstruction using the unprecedented X-ray kinematic results: we derive unambiguous Doppler shifts for these selected regions, with values ranging between -2500 and +4000 km s-1 and the typical velocity error less than 200 km s-1. Plasma diagnostics of these regions, derived from line ratios of resolved He-like triplet lines and H-like lines of Si, indicate temperatures largely around 1 keV, which we model as O-rich reverse-shocked ejecta. The ionization age also does not vary considerably over these regions of the remnant. The gratings analysis was complemented by the nondispersed spectra from the same data set, which provided information on emission measure and elemental abundances for the selected Cas A regions. The derived electron density of X-ray emitting ejecta varies from 20 to 200 cm-3. The measured abundances of Mg, Si, S, and Ca are consistent with O being the dominant element in the Cas A plasma. With a diameter of 5', Cas A is the largest source observed with the HETGS to date. We therefore describe the technique we use and some of the challenges we face in the HETGS data reduction from such an extended, complex object.

Fundamental parameters and abundances of metal-poor stars: the SDSS standard BD +17 4708

The atmospheric parameters and iron abundance of the Sloan Digital Sky Survey (SDSS) spectrophotometric standard star BD +17 4708 are critically examined using up-to-date Kurucz model atmospheres, LTE line formation calculations, and reliable atomic data. We find Teff = 6141+-50 K, log g = 3.87+-0.08, and [Fe/H]=-1.74+-0.09. The line-of-sight interstellar reddening, bolometric flux, limb-darkened angular diameter, stellar mass, and the abundances of Mg, Si, and Ca are also obtained. This star is a unique example of a moderately metal-poor star for which the effective temperature can be accurately constrained from the observed spectral energy distribution (corrected for reddening). Such analysis leads to a value that is higher than most spectroscopic results previously reported in the literature (~5950 K). We find that the ionization balance of Fe lines is satisfied only if a low Teff (~5950 K) is adopted. With our preferred Teff (6141 K), the mean iron abundance we obtain from the FeII lines is lower by about 0.15 dex than that from the FeI lines, and therefore, the discrepancy between the mean iron abundance from FeI and FeII lines cannot be explained by overionization by UV photons as the main non-LTE effect. We also comment on non-LTE effects and the importance of inelastic collisions with neutral H atoms in the determination of oxygen abundances in metal-poor stars from the 777 nm OI triplet. (Abridged)

The helium-weak silicon star HR 7224

Aims. HR 7224 is a rapidly rotating He-weak silicon star known as photometrically variable with a period of 1.123 d. Drastic changes of photometric amplitude and period were reported in 2003. We investigate the star spectroscopically to determine the time scales of variability, to derive basic atmospheric parameters, and to give first estimates on possible surface structures. Methods. We investigate time series of more then 570 high-resolution spectra of HR 7224 for radial velocity and line profile variations. The rotation period is determined from period analysis of data. Comparing radial velocity and line profile variations we draw first conclusions on possible surface structures in terms of line strengths. From Balmer and metal lines we determine Teff ,l ogg, v sini ,a nd metal abundances depending on rotation phase. Results. The star shows a remarkable amplitude of radial velocity variation of ± 6k m s −1 . From this variation we deduce a rotation period of 1.12324 d. The period and the double-wave shaped radial velocity curve are in agreement with earlier photometric findings. The observed radial velocity variations can be explained by the rotation period and its harmonics and no further periodic contributions were found in the residuals. HR 7224 has enhanced Si and Fe abundances whereas He is extremely depleted. The star shows line strength variations of all observed elements with the rotation period. Variations of radial velocity, line strength and line shape of silicon lines and their relationships can be explained by assuming two large spots on the stellar surface showing enhanced line strength. From Balmer lines we deduce different temperatures of the star for different rotation phases. The observed difference in amplitudes of the variation of Mg ii and Si ii lines supports the assumption of surface regions of different temperature on this presumably magnetic Cp star. Synthetic uvby colors computed from adapted synthetic spectra confirm the high photometric amplitude reported for the 2003 light curves.

Chandra and XMM-Newton Observations of a Group of Galaxies, HCG 62

We present results from Chandra and XMM-Newton observations of a bright group of galaxies, HCG 62. There are two cavities at about $30{}^{\prime\prime}$ northeast and $20{}^{\prime\prime}$ southwest of the central galaxy in the Chandra image. The energy spectrum shows no significant change in the cavity compared with that in the surrounding region. The radial X-ray profile is described by the sum of the 3-$\beta$ components with core radii of about 2, 10, and 160 kpc. We studied the radial distributions of the temperature and the metal abundance with a joint spectral fit for both data; two temperatures were required in the inner $r< 2'$ (36 kpc) region. A sharp drop of the temperature at $r \sim 5'$ implies a gravitational mass density even lower than the gas density, suggesting that the gas may not be in hydrostatic equilibrium. The Fe and Si abundances are 1–2 solar at the center, and drop to about 0.1 solar at $r \sim 10'$. The O abundance is less than 0.5 solar, and shows a flatter profile. The observed metal distribution supports the view that iron and silicon are produced by type Ia supernova (SN Ia) in the central galaxy, while galactic winds by SN II have caused a wide distribution of oxygen. The supporting mechanism of the cavity is discussed. The pressure for the sum of electrons and the magnetic field is too low to displace the hot group gas, and the required pressure due to high-energy protons is nearly 700-times higher than the electron pressure. This leaves the origin of the cavities a puzzle; we also discuss other possible origins of the cavities.

Enrichment in the Centaurus cluster of galaxies

We perform a detailed spatially-resolved, spectroscopic, analysis of the core of the Centaurus cluster of galaxies using a deep Chandra X-ray observation and XMM-Newton data. The Centaurus cluster core has particularly high metallicity, upto twice Solar values, and we measure the abundances of Fe, O, Ne, Mg, Si, S, Ar, Ca and Ni. We map the distribution of these elements in many spatial regions,and create radial profiles to the east and west of the centre. The ratios of the most robustly determined elements to iron are consistent with Solar ratios, indicating that there has been enrichment by both Type Ia and Type II supernovae. For a normal initial stellar mass function it represents the products of about 4x10^10 solar masses of star formation. This star formation can have occured either continuously at a rate of 5 solar masses per year for the past 8 Gyr or more,or was part of the formation of the central galaxy at earlier times. Either conclusion requires that the inner core of the Centaurus cluster has not suffered a major disruption within the past 8 Gyr, or even longer.

The Sun's interior metallicity constrained by neutrinos

Abstract Observed solar neutrino fluxes are employed to constrain the interior composition of the Sun. Including the effects of neutrino flavour mixing, the results from Homestake, Sudbury and Gallium experiments constrain the Mg, Si and Fe abundances in the solar interior to be within a factor of 0.89 to 1.34 of the surface values with 68 per cent confidence. If the O and/or Ne abundances are increased in the interior to resolve helioseismic discrepancies with recent standard solar models, then the nominal interior Mg, Si and Fe abundances are constrained to a range of 0.83 to 1.24 relative to the surface. Additional research is needed to determine whether the Sun's interior is metal-poor relative to its surface.

Enhanced Abundances in Three Large‐Diameter Mixed‐Morphology Supernova Remnants

We present an X-ray study of three mixed-morphology supernova remnants (SNRs), HB 21, CTB 1 and HB 3, using archival ASCA and ROSAT data. These data are complemented by archival Chandra X-ray Observatory data for CTB 1 and XMM-Newton X-ray Observatory data for HB 3. The spectra from HB 21 and HB 3 are well-described with a single-temperature thermal plasma in ionization equilibrium, while a two-temperature thermal plasma is found in CTB 1. We found enhanced abundances in all three SNRs. The elemental abundance of Mg is clearly enhanced in CTB 1, while HB 21 has enhanced abundances of Si and S. The situation is not so clear in HB 3 -- the plasma in this SNR either has significantly enhanced abundances of O, Ne and Mg, or it has marginally enhanced abundances of Mg and under-abundant Fe. We discuss the plausibility of mixed-morphology SNR models for the three SNRs and the presence of enhanced abundances. We revise a list of MM SNRs and their properties, compare the three SNRs studied here with other members of this class, and discuss the presence of enhanced elemental abundances in MM SNRs. We also report the ASCA detection of a compact source in the southern part of HB 3. The source spectrum is consistent with a power law with a photon index of ~2.7, and an unabsorbed X-ray flux of ~10^{-12} erg/cm^2/s in the 0.5--10.0 keV band. The column density towards this source differs from that towards the SNR, and it is therefore unlikely they are related.

Abundances of refractory elements in the atmospheres of stars with extrasolar planets

Aims. This work presents a uniform and homogeneous study of chemical abundances of refractory elements in 101 stars with and 93 without known planetary companions. We carry out an in-depth investigation of the abundances of Si, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Na, Mg and Al. The new comparison sample, spanning the metallicity range -0.70 < [Fe/H] < 0.50, fills the gap that previously existed, mainly at high metallicities, in the number of stars without known planets. Methods. We used an enlarged set of data including new observations, especially for the field single comparison stars. The line list previously studied by other authors was improved: on average we analysed 90 spectral lines in every spectrum and carefully measured more than 16600 equivalent widths (EW) to calculate the abundances. Results. We investigate possible differences between the chemical abundances of the two groups of stars, both with and without planets. The results are globally comparable to those obtained by other authors, and in most cases the abundance trends of planet-host stars are very similar to those of the comparison sample. Conclusions. This work represents a step towards the comprehension of recently discovered planetary systems. These results could also be useful for verifying galactic models at high metallicities and consequently improve our knowledge of stellar nucleosynthesis and galactic chemical evolution.

Chemical abundances of 32 mildly metal-poor stars

Context. The formation scenario of the Galactic thick disk is an unresolved problem. Chemical abundances in long-lived dwarf stars of the thin and thick disks provide information of the Galactic disk formation. Aims. We present photospheric abundances of the O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Ni, and Ba elements for 32 mildly metal-poor stars with ${\rm [Fe/H]}\sim -0.7$. According to their kinematics, age, and [ α /Fe] , sample stars are identified to thin disk, thick disk, and halo population memberships. Element abundances for sample stars are discussed as a function of metallicity. Methods. High resolution and high signal-to-noise ratio spectra were obtained with the Coude Echelle Spectrograph mounted on the 2.16 m telescope at the National Astronomical Observatories (Xinglong, China). Effective temperatures were estimated from colour indices, and surface gravities from Hipparcos parallaxes. Stellar abundances were determined from a differential LTE analysis. The kinematics parameters were calculated from the parallax, proper motion, and radial velocity. Stellar ages were determined from theoretical stellar evolution tracks. Results. The average age of the thick disk stars is older than the thin disk stars. Our element abundance results extend and confirm previous works. The oxygen and other α -elements (Mg, Si, Ca, and Ti) abundances of thin and thick disk stars show distinct trends at $\rm [Fe/H]\le-0.60$. The [Al/Fe] behaviour is exactly as an α -element, although the separation for [Na/Fe] of thin and thick disk stars is not clear. The elements V, Cr, and Ni follow Fe very closely, and there is no offset between thin and thick disk stars, but the Sc and Mn abundance trends of the thin and thick disk stars are different, and [Ba/Fe] of thin disk and thick disk stars shows different behaviour.

Chemical Enrichment of the Complex Hot ISM of the Antennae Galaxies. I. Spatial and Spectral Analysis of the Diffuse X‐Ray Emission

We present an analysis of the properties of the hot interstellar medium (ISM) in the merging pair of galaxies known as The Antennae (NGC 4038/39), performed using the deep, coadded ~411 ks Chandra ACIS-S data set. These deep X-ray observations and Chandra's high angular resolution allow us to investigate the properties of the hot ISM with unprecedented spatial and spectral resolution. Through a spatially resolved spectral analysis, we find a variety of temperatures (from 0.2 to 0.7 keV) and Nh (from Galactic to 2x10^21 cm^-2). Metal abundances for Ne, Mg, Si, and Fe vary dramatically throughout the ISM from sub-solar values (~0.2) up to several times solar.

SN 2005cg: Explosion Physics and Circumstellar Interaction of a Normal Type Ia Supernova in a Low‐Luminosity Host

We present the spectral evolution, light curve, and corresponding interpretation for the normal-bright Type Ia Supernova 2005cg discovered by ROTSE-IIIc. The host is a low-luminosity (M_r = -16.75), blue galaxy with strong indications of active star formation and an environment similar to that expected for SNe Ia at high redshifts. Early-time (t ~ -10 days) optical spectra obtained with the HET reveal an asymmetric, triangular-shaped Si II absorption feature at about 6100 \AA with a sharp transition to the continuum at a blue shift of about 24,000 km s^-1. By 4 days before maximum, the Si II absorption feature becomes symmetric with smoothly curved sides. Similar Si II profile evolution has previously been observed in other supernovae, and is predicted by some explosion models, but its significance has not been fully recognized. Although the spectra predicted by pure deflagration and delayed detonation models are similar near maximum light, they predict qualitatively different chemical abundances in the outer layers and thus give qualitatively different spectra at the earliest phases. The Si line observed in SN 2005cg at early times requires the presence of burning products at high velocities and the triangular shape is likely to be formed in an extended region of slowly declining Si abundance that characterizes delayed detonation models. The spectra show a high-velocity Ca II IR feature that coincides in velocity space with the Si II cutoff. This supports the interpretation that the Ca II is formed when the outer layers of the SN ejecta sweep up about 5 x 10^-3 M_sun of material within the progenitor system. (Abridged)

Improved HCN/HNC linelist, model atmospheres and synthetic spectra for WZ Cas

We build an accurate database of 5200 HCN and HNC rotation-vibration energy levels, determined from existing laboratory data. 20 000 energy levels in the Harris et al. (2002b) linelist are assigned approximate quantum numbers. These assignments, lab determined energy levels and Harris et al. (2002b) energy levels are incorporated in to a new energy level list. A new linelist is presented, in which frequencies are computed using the lab determined energy levels where available, and the ab initio energy levels otherwise. The new linelist is then used to compute new model atmospheres and synthetic spectra for the carbon star WZ Cas. This results in better fit to the spectrum of WZ Cas in which the absorption feature at 3.56 µm is reproduced to a higher degree of accuracy than has previously been possible. We improve the reproduction of HCN absorption features by reducing the abundance of Si to [Si/H] = –0.5 dex, however, +

Blue Luminous Stars in Nearby Galaxies: Quantitative Spectral Analysis of M33 B‐Type Supergiant Stars

We present the detailed spectral analysis of a sample of M33 B-type supergiant stars, aimed at the determination of their fundamental parameters and chemical composition. The analysis is based on a grid of non-LTE metal line-blanketed model atmospheres including the effects of stellar winds and spherical extension computed with the code FASTWIND. Surface abundance ratios of C, N, and O are used to discuss the chemical evolutionary status of each individual star. The comparison of observed stellar properties with theoretical predictions of massive star evolutionary models shows good agreement within the uncertainties of the analysis. The spatial distribution of the sample allows us to investigate the existence of radial abundance gradients in the disk of M33. The comparison of stellar and H II region O abundances (based on direct determinations of the electron temperature of the nebulae) shows good agreement. Using a simple linear radial representation, the stellar oxygen abundances result in a gradient of -0.0145 ± 0.005 dex arcmin-1 (or -0.06 ± 0.02 dex kpc-1) up to a distance equal to ~1.1 times the isophotal radius of the galaxy. A more complex representation cannot be completely discarded by our stellar sample. The stellar Mg and Si abundances follow the trend displayed by O abundances, although with shallower gradients. These differences in gradient slope cannot be explained at this point. The derived abundances of the three α-elements yield solar metallicity in the central regions of the disk of M33. A comparison with recent planetary nebula data from Magrini and coworkers indicates that the disk of M33 has not suffered from a significant O enrichment in the last 3 Gyr.

Stellar Coronal Abundances at Intermediate‐Activity Levels: ξ UMa

We present an analysis of Chandra High Energy Transmission Grating (HETG) spectra of the corona of the critical intermediate-activity, quadruple stellar system ξ UMa. Using the maximum A/B subsystem separation in 2001, we attempted to resolve for the first time in X-rays the two components using the HETG Medium Energy Grating (MEG). We found the Aa component of the system to be at least 2 orders of magnitude fainter than the Bb component. We used the Markov Chain Monte Carlo method to reconstruct differential emission measures (DEMs) and abundances and discuss first ionization potential (FIP) issues. The reconstructed DEMs showed two pronounced peaks at log T ≈ 6.5 and log T ≈ 7.0 K, respectively, similar to brighter solar active regions. A plot of coronal abundances, with respect to stellar photospheric, versus FIP reveals that the FIP behavior of ξ UMa is intermediate between less and more active stars, commensurate with its X-ray luminosity. The abundances of Mg, Fe, and Si are just subsolar, with Fe having the lowest abundance of these. The low-FIP elements Na and Al have similar abundances, and they are both higher than the Mg, Fe, and Si group. The abundances show a minimum at S, rising gradually to Ne, which is higher than photospheric, as has been seen by other authors on similar stars. Some of the FIP behavior seen here is predicted by the new ponderomotive force model of Laming.