- ID:
- ivo://CDS.VizieR/J/A+A/456/953
- Title:
- Narrow-band imaging of 6 Seyfert-2 galaxies
- Short Name:
- J/A+A/456/953
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While [OIII] narrow-band imaging is commonly used to measure the size of the narrow-line regions (NLRs) in active galactic nuclei (AGNs), it can be contaminated by emission from surrounding starbursts. Recently, we have shown that long-slit spectroscopy provides a valuable alternative approach to probe the size in terms of AGN photoionisation. Moreover, several parameters of the NLR can be directly accessed. We here apply the same methods developed and described for the Seyfert-2 galaxy NGC1386 to study the NLR of five other Seyfert-2 galaxies by using high-sensitivity spatially-resolved optical spectroscopy obtained at the VLT and the NTT. We probe the AGN-photoionisation of the NLR and thus, its "real" size using diagnostic line-ratio diagrams. We derive physical properties of the NLR such as reddening, ionisation parameter, electron density, and velocity as a function of distance from the nucleus. For NGC5643, the diagnostic diagrams unveil a similar transition between line ratios falling in the AGN regime and those typical for HII regions as found for NGC1386, thus determining the size of the NLR. For the other four objects, all measured line ratios fall in the AGN regime. In almost all cases, both electron density and ionisation parameter decrease with radius. Deviations from this general behaviour (such as a secondary peak) seen in both the ionisation parameter and electron density can be interpreted as signs of shocks from the interaction of a radio jet and the NLR gas. In several objects, the gaseous velocity distribution is characteristic for rotational motion in an (inclined) emission-line disk in the centre. We compare our results to those of NGC1386 and show that the latter can be considered as prototypical also for this larger sample. We discuss our findings in detail for each object.
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- ID:
- ivo://CDS.VizieR/J/A+A/459/55
- Title:
- Narrow-band imaging of 5 Seyfert-1 galaxies
- Short Name:
- J/A+A/459/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spatially resolved emission-line spectroscopy is a powerful tool to determine the physical conditions in the narrow-line region (NLR) of active galactic nuclei (AGNs). We recently used optical long-slit spectroscopy to study the NLRs of a sample of six Seyfert-2 galaxies. We have shown that such an approach, in comparison to the commonly used [OIII] narrow-band imaging alone, allows us to probe the size of the NLR in terms of AGN photoionisation. Moreover, several physical parameters of the NLR can be directly accessed. We here apply the same methods to study the NLR of six Seyfert-1 galaxies and compare our results to those of Seyfert-2 galaxies. We employ diagnostically valuable emission-line ratios to determine the physical properties of the NLR, including the core values and radial dependencies of density, ionisation parameter, and reddening. Tracking the radial change of emission-line ratios in diagnostic diagrams allows us to measure the transition between AGN-like and HII-like line excitation, and thus we are able to measure the size of the NLR. In the diagnostic diagrams, we find a transition between line ratios falling in the AGN regime and those typical for HII regions in two Seyfert-1 galaxies, thus determining the size of the NLR. The central electron temperature and ionisation parameter are in general higher in type-1 Seyferts than in type 2s. In almost all cases, both electron density and ionisation parameter decrease with radius. In general, the decrease is faster in Seyfert-1 galaxies than in type 2s. In several objects, the gaseous velocity distribution is characteristic for rotational motion in an (inclined) emission-line disk in the centre. We give estimates of the black hole masses. We discuss our findings in detail for each object.
- ID:
- ivo://CDS.VizieR/II/26A
- Title:
- Narrow-band photometry of early-type stars
- Short Name:
- II/26A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A compilation of the photoelectric measurements in the Barbier-Morguleff system is presented for 773 stars of spectral types O8 to F6. 706 stars have been measured at least twice. The passbands (in Angstroems) and the mean photometric errors of the indexes C(j)-C(2) (in magnitudes) are: ----------------------- Band Interval m.e. ----------------------- C(1) 6000-5900 0.0318 C(2) 5000-4900 --- C(3) 4905-4815 0.0073 C(4) 4380-4310 0.0100 C(5) 4070-4010 0.0102 C(6) 3965-3925 0.0201 C(7) 3780-3720 0.0195 C(8) 3650-3575 0.0189 ----------------------- Regarding the catalog Pass Bands Morguleff and Gerbaldi (1975) note the following: These spectral intervals permit the determination of certain physical characteristics .... The pass bands 1 and 5 lead us to calculate red and blue gradients. The equivalent widths of the H(beta), H(gamma) lines of hydrogen and the K lines of Ca II are derived from band 3, 4, and 6. Bands 7 and 8 measure the Balmer jump. Listed in the catalog file are the normalized magnitudes corresponding to the above pass bands. The normalized magnitude of a pass band, C(j), is defined as the color index of the magnitude in the band minus the magnitude of the second band, C(2). See Morguleff and Gerbaldi (1975) for a brief discussion of conservation of the system and mean errors across all stars.
- ID:
- ivo://CDS.VizieR/II/21A
- Title:
- Narrow-Band Photometry of Late-Type Stars
- Short Name:
- II/21A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is a compilation of photoelectric photometry obtained as part of a program investigating the distribution of stars and stellar matter perpendicular to the galactic plane. Compared to the publication, the "catalog" file does not include the position, the spectral type, the source of the UBV photometry, and neither the number of measurements in the narrow-band filters. The observations have mainly been made with the 33cm photographic tube of the Uppsaala double refractor, using a diaphragm of 0.7mm corresponding to 33". A small number of measurements have also been made with the 15cm Zeiss-Heyde astrograph. The observations were made between January 1967 and April 1968.
- ID:
- ivo://CDS.VizieR/J/A+A/361/245
- Title:
- 6 new Beta Cep stars
- Short Name:
- J/A+A/361/245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ground-based follow-up photometry in the Geneva seven-colour photometric system of six new {beta} Cep stars. The variability of these objects was originally found from the HIPPARCOS mission. The new data provided here allowed us to confirm their {beta} Cep-type nature, to detect the pulsational frequencies and to identify the degrees of the pulsation modes. For definitions of the Geneva photometric system, see <GCPD/13>.
- ID:
- ivo://CDS.VizieR/J/ApJS/227/12
- Title:
- NGVS XXV. Virgo globular clusters photometry
- Short Name:
- J/ApJS/227/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The central region of the Virgo cluster of galaxies contains thousands of globular clusters (GCs), an order of magnitude more than the numbers found in the Local Group. Relics of early star formation epochs in the universe, these GCs also provide ideal targets to test our understanding of the Spectral Energy Distributions (SEDs) of old stellar populations. Based on photometric data from the Next Generation Virgo cluster Survey (NGVS) and its near-infrared counterpart NGVS-IR, we select a robust sample of ~2000 GCs with excellent photometry and spanning the full range of colors present in the Virgo core. The selection exploits the well defined locus of GCs in the uiK diagram and the fact that the globular clusters are marginally resolved in the images. We show that the GCs define a narrow sequence in 5-dimensional color space, with limited but real dispersion around the mean sequence. The comparison of these SEDs with the predictions of eleven widely used population synthesis models highlights differences between models, and also shows that no single model adequately matches the data in all colors. We discuss possible causes for some of these discrepancies. Forthcoming papers of this series will examine how best to estimate photometric metallicities in this context, and compare the Virgo globular cluster colors with those in other environments.
- ID:
- ivo://CDS.VizieR/II/41
- Title:
- 420nm CN and G bands in G8-K5 spectra
- Short Name:
- II/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measurements of the {lambda}4200{AA} CN band are presented for 712 late-type stars. G band data are also included for 212 of these stars. Mean errors of absolute magnitudes derived from CN intensities are at least 1.5 mag. Spectral type determined by G band intensity has a mean deviation of 0.15 class from the MK type for G to K1 stars. The file photom.dat contains 712 data records in the form of CN ratios and G-band ratios, with annotations. The CN ratio is the ratio of the sum of the intensities in the 4097-4149{AA} and 4230-4283{AA} wavelength ranges to the intensity in the 4164-4214{AA} range. The latter contains the CN absorption band, and the first two ranges serve as nearby continuum references. The ratio is a measure of the depth of the absorption in the CN band. Values greater than 2 indicate absorption in the band. The G-band ratio is similarly the ratio of the sum of the intensities in the 4230-4270{AA} and 4342-4380{AA} wavelength ranges to the intensity in the 4285-4315{AA} range.
- ID:
- ivo://CDS.VizieR/J/A+A/401/657
- Title:
- Non-linear limb-darkening law for LTE models. II.
- Short Name:
- J/A+A/401/657
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As an extension of our previous investigations on stellar atmospheres (Claret, 2000, Cat. <J/A+A/363/1081>), the limb-darkening coefficients for the Geneva and Walraven photometric systems are presented for the first time using the ATLAS and PHOENIX models. They cover a wide range of values of logg, T_eff_, metallicities and microturbulent velocities. In addition to the traditional applications of limb-darkening coefficients, the present ones are now being used in the interpretation of phase shift of B and A-F type pulsating stars.
- ID:
- ivo://CDS.VizieR/J/A+A/401/271
- Title:
- Outbursts in the Be star HR 2501
- Short Name:
- J/A+A/401/271
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several mostly unrelated periods or time scales characterize the variability of HR 2501. This star is a new lambda Eri star with a period of 0.79187d. This star also exhibits a mid- to long-term variability of characteristic time ~500d, most probably a consequence of the recurrent outbursts of matter from the rapidly rotating Be star towards its disk.
- ID:
- ivo://CDS.VizieR/J/A+A/422/511
- Title:
- Oxygen abundance in M101 HII regions
- Short Name:
- J/A+A/422/511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the oxygen abundance determination for 90 HII regions in the inner parts of the grand design galaxy M101. The abundances were derived employing the P method (Pilyugin, 2001A&A...369..594P). A comparison is made with previous determinations using another calibration and direct measurements of electron temperature to derive the oxygen abundance. The results show agreement with the abundances derived from the electron temperature method and also show that the older calibration is not as accurate as the P method.
