Gloria Delgado-Inglada

CALIFA, the Calar Alto Legacy Integral Field Area survey IV. Third public data release

We present a dynamical classification system for galaxies based on the shapes of their circular velocity curves (CVCs). We derive the CVCs of 40 SAURON and 42 CALIFA galaxies across Hubble sequence via a full line-of-sight integration as provided by solutions of the axisymmetric Jeans equations. We use Principal Component Analysis (PCA) applied to the circular curve shapes to find characteristic features and use a k-means classifier to separate circular curves into classes. This objective classification method identifies four different classes, which we name Slow-Rising (SR), Flat (F), Sharp-Peaked (SP) and Round-Peaked (RP) circular curves. SR-CVCs are mostly represented by late-type spiral galaxies (Scd-Sd) with no prominent spheroids in the central parts and slowly rising velocities; F-CVCs span almost all morphological types (E,S0,Sab,Sb-Sbc) with flat velocity profiles at almost all radii; SP-CVCs are represented by early-type and early-type spiral galaxies (E,S0,Sb-Sbc) with prominent spheroids and sharp peaks in the central velocities. RP-CVCs are represented by only two morphological types (E,Sa-Sab) with prominent spheroids, but RP-CVCs have much rounder peaks in the central velocities than SP-CVCs. RP-CVCs are typical for high-mass galaxies, while SR-CVCs are found for low-mass galaxies. Intermediate-mass galaxies usually have F-CVCs and SP-CVCs. Circular curve classification presents an alternative to typical morphological classification and may be more tightly linked to galaxy evolution.This paper describes the Third Public Data Release (DR3) of the Calar Alto Legacy Integral Field Area (CALIFA) survey. Science-grade quality data for 667 galaxies are made public, including the 200 galaxies of the Second Public Data Release (DR2). Data were obtained with the integral-field spectrograph PMAS/PPak mounted on the 3.5m telescope at the Calar Alto Observatory. Three different spectral setups are available, i) a low-resolution V500 setup covering the wavelength range 3749-7500 AA (4240-7140 AA unvignetted) with a spectral resolution of 6.0 AA (FWHM), for 646 galaxies, ii) a medium-resolution V1200 setup covering the wavelength range 3650-4840 AA (3650-4620 AA unvignetted) with a spectral resolution of 2.3 AA (FWHM), for 484 galaxies, and iii) the combination of the cubes from both setups (called COMBO), with a spectral resolution of 6.0 AA and a wavelength range between 3700-7500 AA (3700-7140 AA unvignetted), for 446 galaxies. The Main Sample, selected and observed according to the CALIFA survey strategy covers a redshift range between 0.005 and 0.03, spans the color-magnitude diagram and probes a wide range of stellar mass, ionization conditions, and morphological types. The Extension Sample covers several types of galaxies that are rare in the overall galaxy population and therefore not numerous or absent in the CALIFA Main Sample. All the cubes in the data release were processed using the latest pipeline, which includes improved versions of the calibration frames and an even further improved im- age reconstruction quality. In total, the third data release contains 1576 datacubes, including ~1.5 million independent spectra. It is available at this http URL

Ionization correction factors for planetary nebulae – I. Using optical spectra

We compute a large grid of photoionization models that covers a wide range of physical parameters and is representative of most of the observed PNe. Using this grid, we derive new formulae for the ionization correction factors (ICFs) of He, O, N, Ne, S, Ar, Cl, and C. Analytical expressions to estimate the uncertainties arising from our ICFs are also provided. This should be useful since these uncertainties are usually not considered when estimating the error bars in element abundances. Our ICFs are valid over a variety of assumptions such as the input metallicities, the spectral energy distribution of the ionizing source, the gas distribution, or the presence of dust grains. Besides, the ICFs are adequate both for large aperture observations and for pencil-beam observations in the central zones of the nebulae. We test our ICFs on a large sample of observed PNe that extends as far as possible in ionization, central star temperature, and metallicity, by checking that the Ne/O, S/O, Ar/O, and Cl/O ratios show no trend with the degree of ionization. Our ICFs lead to significant differences in the derived abundance ratios as compared with previous determinations, especially for N/O, Ne/O, and Ar/O.

Candidate planetary nebulae in the IPHAS photometric catalogue

Context. We have carried out a semi-automated search for planetary nebulae (PNe) in the INT photometric H-alpha survey (IPHAS) catalogue. We present the PN search and the list of selected candidates. We cross correlate the selected candidates with a number of existing infrared galactic surveys in order to gain further insight into the nature of the candidates. Spectroscopy of a subset of objects is used to estimate the number of PNe present in the entire candidate list. Aims. The overall aim of the IPHAS PN project is to carry out a deep census of PNe in the northern Galactic plane, an area where PN detections are clearly lacking. Methods. The PN search is carried out on the IPHAS photometric catalogue. The candidate selection is based on the IPHAS and 2MASS/UKIDSS colours of the objects and the final candidate selection is made visually. Results. From the original list of ∼600 million IPHAS detections we have selected a total of 1005 objects. Of these, 224 are known objects, leaving us with 781 PN candidates. Based on the initial follow-up spectroscopy, we expect the list to include very young and proto-PNe in addition to genuine, normal PNe (∼16%) and emission line objects other than PNe. We present additional criteria to select the most probable PN candidates from our candidate list.

Oxygen enrichment in carbon-rich planetary nebulae

We study the relation between the chemical composition and the type of dust present in a group of 20 Galactic planetary nebulae (PNe) that have high quality optical and infrared spectra. The optical spectra are used, together with the best available ionization correction factors, to calculate the abundances of Ar, C, Cl, He, N, Ne, and O relative to H. The infrared spectra are used to classify the PNe in two groups depending on whether the observed dust features are representative of oxygen-rich or carbon-rich environments. The sample contains one object from the halo, eight from the bulge, and eleven from the local disc. We compare their chemical abundances with nucleosynthesis model predictions and with the ones obtained in seven Galactic H II regions of the solar neighbourhood. We find evidence of O enrichment (by

C/O Abundance Ratios, Iron Depletions, and Infrared Dust Features in Galactic Planetary Nebulae

\sim

New young planetary nebulae in IPHAS

0.3 dex) in all but one of the PNe with carbon-rich dust (CRD). Our analysis shows that Ar, and especially Cl, are the best metallicity indicators of the progenitors of PNe. There is a tight correlation between the abundances of Ar and Cl in all the objects, in agreement with a lockstep evolution of both elements. The range of metallicities implied by the Cl abundances covers one order of magnitude and we find significant differences in the initial masses and metallicities of the PNe with CRD and oxygen-rich dust (ORD). The PNe with CRD tend to have intermediate masses and low metallicities, whereas most of the PNe with ORD show higher enrichments in N and He, suggesting that they had high-mass progenitors.

Analysis of chemical abundances in planetary nebulae with [WC] central stars - II. Chemical abundances and the abundance discrepancy factor

We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample objects have deep optical spectra of good quality, and most of them also have ultraviolet observations. We use these observations to derive the iron abundances and the C/O abundance ratios in a homogeneous way for all the objects. We compile detections of infrared dust features from the literature and we analyze the available Spitzer/IRS spectra. Most of the PNe have C/O ratios below one and show crystalline silicates in their infrared spectra. The PNe with silicates have C/O <1, with the exception of Cn 1-5. Most of the PNe with dust features related to C-rich environments (SiC or the 30 ?m feature usually associated to MgS) have C/O 0.8. Polycyclic aromatic hydrocarbons are detected over the full range of C/O values, including 6 objects that also show silicates. Iron abundances are low in all the objects, implying that more than 90% of their iron atoms are deposited into dust grains. The range of iron depletions in the sample covers about two orders of magnitude, and we find that the highest depletion factors are found in C-rich objects with SiC or the 30 ?m feature in their infrared spectra, whereas some of the O-rich objects with silicates show the lowest depletion factors.

The S2N2 metallicity calibrator and the abundance gradient of M 33

Aims. We search for very small-diameter galactic planetary nebulae (PNe) representing the earliest phases of PN evolution. The IPHAS catalogue of Hα-emitting stars provides a useful basis for this study since all sources present in this catalogue must be of small angular diameter. Methods. The PN candidates are selected based on their location in two colour−colour diagrams: IPHAS (r � − Hα )v s. (r � − i � ), and 2MASS (J − H )v s. (H − Ks). Spectroscopic follow-up was carried out on a sample of candidates to confirm their nature. Results. We present a total of 83 PN candidates. We were able to obtain spectra or find the classification from the literature for 35 candidates. Five of these objects are likely to be new PNe, including one large bipolar PN discovered serendipitously close to an emission-line star. PN distances deduced from extinction-distance relations based on IPHAS field-star photometry are presented for the first time. These yield distance estimates for our objects in the range 2 kpc and 6 kpc. From the data in hand, we conclude that four of the discovered objects are probably young PNe.

s-process enrichment in the planetary nebula NGC 3918. Results from deep echelle spectrophotometry

Aims. We present the abundance analysis of 12 planetary nebulae ionized by [WC]-type stars and weak-emission-line stars (wels) obtained from high-resolution spectrophotometric data. Our main aims are to determine the chemical composition of the nebulae and to study the behaviour of the abundance discrepancy problem (ADF) in this type of planetary nebulae. Methods. The detection of a large number of optical recombination lines (ORLs) and collisionally excited lines (CELs) from different ions (O + ,O ++ ,C ++ ,C +3 and Ne ++ ) were presented previously. Most of the ORLs were reported for the first time in these PNe, which increased the sample of PNe with detected faint ORLs. Ionic abundances were determined from the available CELs and ORLs, using previously determined physical conditions. Based on these two sets of ionic abundances, we derived the total chemical abundances in the nebulae using suitable ionization correction factors (when available). Results. In spite of the [WC] nature of the central stars, moderate ADF(O ++ ) in the range from 1.2 to 4 were found for all the objects. We found that when the quality of the spectra is high enough, the ORLs O ++ /H + abundance ratios obtained from different multiplets excited mainly by recombination are very similar. Possible dependence of ADFs on some nebular characteristics such as surface brightness and nebular diameter were analysed, but we found no correlation. Abundances derived from CELs were corrected by determining the t 2 temperature fluctuation parameter. O abundances for PNe, derived from ORLs, are in general higher than the solar abundance. We derived the C/O ratio from ORLs and N/ Oa ndα-element/O ratios from CELs and found that these PNe are, on average, richer in N and C than the average of the large PN samples. About half of our sample is C-rich (C/O > 1). The growth of α-elements is correlated with the O abundance. Comparing the N/ Oa nd C/O ratios with those derived from stellar evolution models, we estimate that about half of our PNe have progenitors with initial masses similar to or larger than 4 M� . No correlation was found between the stellar [WC] type and the nebular chemical abundances. A rough O abundance gradient computed for our limited PN sample, compared with the gradient obtained for H ii regions, shows that there is a large dispersion in estimates of the PNe O abundance for a given Galactocentric distance. The PN gradient is flatter than that for H ii regions and at the solar distance and farther out, the PNe have a higher O abundance than H ii regions, similarly to what is found in other spiral galaxies. This fact has no convincing explanation so far.

THE OXYGEN ABUNDANCE IN THE SOLAR NEIGHBORHOOD

We introduce the log(Hα/[S II]λλ6717+6731) versus log(Hα/[N II]λ6583) (S2N2) diagnostic diagram as a metallicity and ionization parameter indicator for H II regions in external galaxies. The location of H II regions in the S2N2 diagram was studied both empirically and theoretically. We found that, for a wide range of metallicities, the S2N2 diagram gives single-valued results in the metallicity‐ionization parameter plane. We demonstrate that the S2N2 diagram is a powerful tool to estimate metallicities of high-redshift (z ∼ 2) H II galaxies. Finally, we derive the metallicity for 76 H II regions in M 33 from the S2N2 diagram and calculate an O/H abundance gradient for this galaxy of −0.05 (±0.01) dex kpc −1 .