- ID:
- ivo://CDS.VizieR/J/A+A/578/A51
- Title:
- Near-IR photometry of AGB stars in IC 1613
- Short Name:
- J/A+A/578/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated the photometric properties of asymptotic giant branch (AGB) stars of dwarf irregular galaxy IC 1613 and its metallicity. We used near-infrared JHKs photometric data obtained with the WIRCam array on Canada-France-Hawaii Telescope (CHFT). The optical gi imaging data of previous study were cross-matched with ours to distinguish the stellar populations in the galaxy and to select the AGB stars. We also separated the C stars from the M-giant stars in the JHKs color-color diagram. We identified 140 C stars and 306 M-giant stars in IC 1613. The (J-Ks) color histogram of AGB stars shows the main peak of M-giant stars and the red tail of C stars. The broad color distribution of M-giant stars and the isochrones in color magnitude diagram indicate that IC 1613 has a wide range of intermediate-age stars. We also know that most C stars were formed over the past 2-8Gyr according the M_bol-age relation. The C/M ratio of 0.46+/-0.05 was estimated and [Fe/H] abundance of -1.23+/-0.06 was derived from the C/M ratio. Radial distributions of C/M ratio and metallicity show the shallow trend of the negative metallicity gradient from the center. The local C/M ratio also indicates that the HI cavity has higher C/M values than the bright HI spot and HI gas region. However, the low [Fe/H] value near the central region of the galaxy is likely to be caused by the change in age of the dominant stellar population according to the radial distance, not the real metallicity variation. It might also be that relatively younger and metal-rich C stars are concentrated in the center of the galaxy, while the M-giant stars were homogeneously distributed from the center to the borders of the galaxy.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/454/717
- Title:
- Near-IR photometry of C and AGB stars in NGC 6822
- Short Name:
- J/A+A/454/717
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Images of JHK and gi obtained with the Canada-France-Hawaii Telescope are used to investigate the stellar contents of the resolved asymptotic giant branch (AGB) population in the area of 3.6'x6.3' on the central bar of the dwarf irregular galaxy NGC 6822. The upper envelope of near-infrared (J-K, K) and (H-K, K) color-magnitude diagrams (CMDs) shows four components of main-sequence stars, foreground stars, massive supergiants, and AGB stars. These components are also noticeable in the bright part of (g-i, g) CMD. We select AGB stars in NGC 6822 from the (g-K, g) CMD, which has a long spectral wavelength base line in the color index. There are 141 C stars with a mean absolute magnitude of <M_K_>=-7.60+/-0.50, and with mean colors of <(J-K)_o_>=1.77+/-0.41, and <(H-K)_o_>=0.75+/-0.28. The number ratio of C stars to M-giants (C/M) is estimated as 0.27+/-0.03, while the northern part of the bar has a somewhat lower C/M ratio than the southern part. The (J-K) and (H-K) color distributions of AGB stars contain a main peak of M-giant stars and a red tail of C stars. The broad color distributions for M-giants indicate that NGC 6822 has a wide range of intermediate ages with a peak at log(t_yr_)~9.0. The M_K_ luminosity function (LF) for C stars in the central bar of NGC 6822 is likely to be a Gaussian distribution, while the LF of C stars in the southern part is slightly skewed to the brighter side than in northern part. The mean bolometric magnitude of 141 C stars in NGC 6822 is <M_bol_>=-4.36+/-0.54. The bolometric LF for M-giants extends up to M_bol_=-6.5, while the one for C stars spans -5.8<M_bol_<-3.5.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A35
- Title:
- Near-IR photometry of C stars in NGC 205
- Short Name:
- J/A+A/543/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated the distribution of resolved asymptotic giant branch (AGB) stars over a much larger area than covered by previous near-infrared studies in the nearby dwarf elliptical galaxy NGC 205. Using data obtained with the WIRCam near-infrared imager of the CFHT, we selected the AGB stars in the JHKs color - magnitude diagrams, and separated the C stars from M-giant stars in the JHKs color - color diagram. We identified 1,550 C stars in NGC 205 with a mean absolute magnitude of <M_Ks>=-7.49+/-0.54, and colors of <(J-K)_0>=1.81+/-0.41 and <(H-Ks)_0>=0.76+/-0.24. The ratio of C stars to M-giant stars was estimated to be 0.15+/-0.01 in NGC 205, and the local C/M ratios for the southern region are somewhat lower than those for the northern region. The (J-K) color distributions of AGB stars contain the main peak of the M-giant stars and the red tail of the C stars. A comparison of the theoretical isochrone models with the observed color distribution indicates that most of the bright M-giant stars in NGC 205 were formed at log(t_yr_)~9.0-9.7. The logarithmic slope of the M_Ks_ luminosity function for M-giant stars was estimated to be 0.84+/-0.01, which is comparable with dwarf elliptical galaxies NGC 147 and NGC 185. Furthermore, we found that the logarithmic slopes of the M_Ks_ luminosity function for C and M-giant stars are different to places, implying a different star formation history within NGC 205. The bolometric luminosity function for M-giant stars extends to M_bol_=-6.0mag, and that for C stars spans -5.6<M_bol_<-3.0. The bolometric luminosity function of C stars is unlikely to be a Gaussian distribution and the mean bolometric magnitude of C stars is estimated to be M_bol_=-4.24+/-0.55, which is consistent with our results for dwarf elliptical galaxies NGC 147 and NGC 185.
- ID:
- ivo://CDS.VizieR/J/A+AS/118/557
- Title:
- Near-IR photometry of 86 galaxies. II.
- Short Name:
- J/A+AS/118/557
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this Paper I present a new two-dimensional decomposition technique, which models the surface photometry of a galaxy with an exponential light profile for both bulge and disk and, when necessary, with a Freeman bar. The new technique w as tested for systematic errors on both artificial and real data and compared with widely used one-dimensional decomposition techniques, where the luminosity profile of the galaxy is used. The comparisons indicate that a decomposition of the two-dimensional image of the galaxy with an exponential light profile for both bulge and disk yields the most reproducible and representative bulge and disk parameters. An extensive error analysis was made to determine the reliability of the model parameters. If the model with an exponential bulge profile is a reasonable description of a galaxy, the maximum errors in the derived model parameters are of order 20%. The uncertainties in the model parameters will increase, if the exponential bulge function is replaced by other often used bulge functions as the de Vaucouleurs law. All decomposition methods were applied to the optical and near-infrared data set presented by de Jong & van der Kruit (1994), which comprises 86 galaxies in six passbands.
- ID:
- ivo://CDS.VizieR/J/ApJ/510/637
- Title:
- Near IR properties of Galaxy disks
- Short Name:
- J/ApJ/510/637
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived the near-infrared structural components of a sample of Seyfert and starburst (SBN) host galaxies by fitting near-infrared images with a new two-dimensional decomposition algorithm. An analysis of the fitted parameters shows that Seyfert 1 and SBN bulges resemble normal early-type bulges in structure and color, with (J-K)^c^_b_ about 0.1 mag redder than disk (J-K)^c^_d_. Seyfert 2 bulges, on the other hand, are bluer than normal, with (J-K)^c^_b_{approx}(J-K)^c^_d_. Seyfert disks (especially type 1), but not those of SBNs, are abnormally bright (in surface brightness), significantly more so than even the brightest normal disks. Seyfert disks are also compact, but similar to those in normal early-type spirals. For a given mass, Seyfert and particularly SBN galaxies are abnormally rich in neutral hydrogen, and there is strong, albeit indirect, evidence for lower mass-to-light (M/L) ratios in Seyfert and SBN disks, but normal M/L ratios in their bulges. In Seyfert and SBN galaxies, H I mass fractions and M/L ratios are anticorrelated, and we attribute the high gas mass fractions and low M/L ratios in SBNs and several Seyfert galaxies to ongoing star formation. Such abundant gas in Seyfert galaxies would be expected to inhibit bar formation, which may explain why active galaxies are not always barred.
- ID:
- ivo://CDS.VizieR/J/A+AS/121/507
- Title:
- Near-IR surface photometry of Virgo galaxies
- Short Name:
- J/A+AS/121/507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The basic parameters of galaxies observed in this work: table 3: total H and K' magnitudes derived using circular apertures; table 5: photometric parameters derived along elliptical apertures
- ID:
- ivo://CDS.VizieR/J/A+A/551/A93
- Title:
- Nebular emission from z=~2-3 star-forming galaxies
- Short Name:
- J/A+A/551/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the ingredients, which allow star-forming galaxies to present Ly{alpha} line in emission, we studied the kinematics and gas phase metallicity of the interstellar medium. We used multi-object near-infrared spectroscopy with Magellan/MMIRS to study nebular emission from z=~2-3 star-forming galaxies discovered in three MUSYC fields.
- ID:
- ivo://CDS.VizieR/J/AJ/109/1458
- Title:
- Neighborhoods of 36 loose groups of galaxies
- Short Name:
- J/AJ/109/1458
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have selected 36 loose groups of galaxies from Ramella et al. 1989, with at least five members, and with mean redshift cz>3200km/s. These groups all lie within the first two "slices" of the CfA redshift survey <VII/164> (RA between 8h and 17h, DE between 2655.5 and 38.5 degrees). For each of these groups, we define the "redshift-space neighbourhood" as a region centered on the group coordinates and delimited by a circle of projected radius 1.5xh^-1^ Mpc on the sky, and by a velocity interval of 3000km/s. Table 2 lists the positions, magnitudes, radial velocities (cz) and their errors, for the members of the groups published in RGH89. Coordinates and magnitudes are from Zwicky's CGCG <VII/4>. Unpublished redshifts are marked with an asterisk in the last column. Table 3 lists galaxies within 1.5Mpc (assuming H0=100) and +/-1500 km/s from the centers of the groups in redshift space. Magnitudes and positions are from the Zwicky-Nielsen merged catalog. Some coordinates are better coordinates than Zwicky's, some come from compilations of redshift data that we have used to complement our measurements. Unpublished redshifts are marked with an asterisk in the last column. In this table some galaxies appear twice because a few groups do overlap. We listed the galaxies in common under the labels of both groups.
2439. NEP deep survey at 11um
- ID:
- ivo://CDS.VizieR/J/PASJ/59/S529
- Title:
- NEP deep survey at 11um
- Short Name:
- J/PASJ/59/S529
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the properties of 11um selected sources detected in the early data of the North Ecliptic Pole Deep (NEP-Deep) Survey of AKARI. The data set covers 6 wavelength bands from 2.5 to 11um, with exposure times of 10-20 minutes. This field lies within the CFHT survey with four filter bands (g', r', i', z'), enabling us to establish nearly continuous spectral energy distributions (SEDs) for wavelengths ranging from 0.4 to 11um. The main sample studied here consists of 72 sources whose 11um AB magnitudes are equal to or brighter than 18.5 (144uJy), which is complete to more than 90%. The 11um band has an advantage of sampling star-forming galaxies with low-to-medium redshifts, since the prominent PAH feature shifts into this band. As expected, we find that the majority (71%) of 11um bright sources are star-forming galaxies at 0.2~<z~<0.7 with L_IR_~10^10^-10^12^~L_{sun}_ based on detailed modelling of the SEDs. We also find four AGNs lying at various redshifts in the main sample. In addition, we discuss a few sources that have non-typical SEDs of the main sample, including a brown-dwarf candidate, a steep power-law source, a flat-spectrum object, and an early-type galaxy at moderate redshift.
- ID:
- ivo://CDS.VizieR/J/A+A/446/97
- Title:
- NEP Distant Cluster Radio Galaxies
- Short Name:
- J/A+A/446/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A complete sample of 18 X-ray selected clusters of galaxies belonging to the ROSAT North Ecliptic Pole (NEP) survey has been observed with the Very Large Array at 1.4GHz in B configuration. These are the most distant clusters in the X-ray survey with redshift in the range 0.3<z<0.8. Seventy-nine radio sources are detected within half an Abell radius with an observed peak brightness >=0.17mJy/beam, except for three sources, belonging to the same cluster, which have a higher peak brightness limit of 0.26mJy/beam. The NEP field source counts are in good agreement with the source counts of a comparison survey, the VLA-VIRMOS deep field survey, indicating that the NEP sample is statistically complete. Thirty-two out of the 79 sources are within 0.2 Abell radii, twenty-two of them are considered cluster members based on spectroscopic redshifts or their optical magnitude and morphological classification. The cluster radio galaxies are used to construct the Radio Luminosity Function (RLF) of distant X-ray selected clusters. A comparison with two nearby cluster RLFs shows that the NEP RLF lies above the local ones, has a steeper slope at low radio powers (<=10^24^W/Hz) and shows no evidence for a break at about 6x10^24^W/Hz which is observed in the nearby cluster RLFs. We discuss briefly the origin and possible explanations of the differences observed in the radio properties of nearby and distant clusters of galaxies. The main result of this study is that the RLF of the distant X-ray clusters is very different from that of the local rich Abell clusters.