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4221. Near-IR photometry of AGB stars in NGC 185
ID:
ivo://CDS.VizieR/J/A+A/437/61
Title:
Near-IR photometry of AGB stars in NGC 185
Short Name:
J/A+A/437/61
Date:
21 Oct 2021
Publisher:
CDS
Description:
J, H and K' images obtained with the Canada-France-Hawaii Telescope were used to investigate the stellar contents of asymptotic giant branch (AGB) in the dwarf elliptical galaxy NGC 185. The bright parts of (K, J-K) and (K, H-K) color-magnitude diagrams consist of a group of brights blue stars, a dominant populations of M-giants, and a red C star population. There were 73 C stars with a mean magnitude of <K>=16.26+/-0.38, corresponding to <M_K_>=-7.93 and mean colors of <(J-k)_0_>=2.253 and <(H-K)_0_>=0.865. The number ratio of C stars to M-giants was estimated to be 0.11+/-0.04 without any radial gradient from the center of NGC 185. The (J-K) and (H-K) color distributions of AGB stars showed an M-giant pick, blue and red tails, where the latter two correspond to AGB stars younger than those along M-giant peak and C stars. The bolometric luminosity functions of M-giants and C stars indicated that the M-giant AGB sequence has terminated at M_bol_=-6.2, while the most luminous C star very similar to that of Nowotny et al. (2003, Cat. <J/A+A/403/93>) which was derived from VI band photometry. The logarithmic slope of the luminosity function for bright M-giant stars was estimated to be 0.83+/-0.02 in K band. Theoritical isochrone models, compared with the observed near-infrared photometric properties of AGB stars, indicated that the star formation in NGC 185 has a wide range of age span with possibly two different epochs of star formation.
4222. Near IR Photometry of a Sample of IRAS Point Sources
ID:
ivo://CDS.VizieR/II/177
Title:
Near IR Photometry of a Sample of IRAS Point Sources
Short Name:
II/177
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results are given for the 516 sources that we have observed from La Silla (452 in the southern hemisphere, plus 64 in the range 0 to 20deg). For each source, the IRAS name is given followed by the epoch of observation (with the convention given in Table 1), the J, H, K, L', M magnitudes that we have obtained, then three classifications based on IRAS Low Resolution Spectra (LRS), IRAS broad-band photometry (VH) and the combination of IRAS broad-band photometry with our near-infrared photometry (Val), and, finally, one association.
4223. Near-IR photometry of C and AGB stars in NGC 6822
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.
4224. Near-IR photometry of C stars in NGC 205
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.
4225. Near-IR photometry of 86 galaxies. II.
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.
4226. Near-IR photometry of PMS stars in rho Oph
ID:
ivo://CDS.VizieR/J/A+A/452/245
Title:
Near-IR photometry of PMS stars in rho Oph
Short Name:
J/A+A/452/245
Date:
21 Oct 2021
Publisher:
CDS
Description:
The aim of this paper is to provide a measurement of the mass accretion rate in a large, complete sample of objects in the core of the star forming region rho Oph. The sample includes most of the objects (104 out of 111) with evidence of a circumstellar disk from mid-infrared photometry; it covers a stellar mass range from about 0.03 to 3M_{sun}_ and it is complete to a limiting mass of ~0.05M_{sun}_. We used J and K-band spectra to derive the mass accretion rate of each object from the intensity of the hydrogen recombination lines, Pa{beta} or Br{gamma}. For comparison, we also obtained similar spectra of 35 diskless objects.
4227. Near-IR photometry of Sh 2-235
ID:
ivo://CDS.VizieR/J/MNRAS/414/1526
Title:
Near-IR photometry of Sh 2-235
Short Name:
J/MNRAS/414/1526
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the Spitzer-Infrared Array Camera (IRAC) images of the S235 star-forming complex that includes the east 1, east 2, central, S235A and S235B regions. In addition, we present the near-infrared images of the S235A and S235B regions. The IRAC photometry reveals on-going star formation, with 86 Class 0/I and 144 Class II young stellar objects (YSOs) in the entire S235 complex.
4228. Near-IR photometry of Sh2-157 and Sh2-152
ID:
ivo://CDS.VizieR/J/ApJ/693/430
Title:
Near-IR photometry of Sh2-157 and Sh2-152
Short Name:
J/ApJ/693/430
Date:
21 Oct 2021
Publisher:
CDS
Description:
Near-infrared JHK' and H_2_{nu}=1-0S(1) imaging observations of the star-forming regions Sh2-157 and Sh2-152 are presented. The data reveal a cluster of young stars associated with H_2_ line emission in each region. Additionally, many IR point sources are found in the dense core of each molecular cloud. Most of these sources exhibit infrared color excesses typical of T Tauri stars, Herbig Ae/Be stars, and protostars. Several display the characteristics of massive stars. We calculate histograms of the K'-magnitude and [H-K'] color for all sources, as well as two-color and color-magnitude diagrams. The stellar populations inside and outside the clusters are similar, suggesting that these systems are rather evolved. Shock-driven H_2_ emission knots are also detected, which may be related to evident subclusters in an earlier evolutionary stage.
4229. Near-IR polarimetry of Galactic center sources
ID:
ivo://CDS.VizieR/J/A+A/557/A82
Title:
Near-IR polarimetry of Galactic center sources
Short Name:
J/A+A/557/A82
Date:
21 Oct 2021
Publisher:
CDS
Description:
Infrared observations of the Galactic center (GC) provide a unique opportunity to study stellar and bow-shock polarization effects in a dusty environment. The goals of this work are to present new Ks- and Lp-band polarimetry on an unprecedented number of sources in the central parsec of the GC, thereby expanding our previous results in the H- and Ks-bands. We use AO-assisted Ks- and Lp-band observations, obtained at the ESO VLT. High precision photometry and the new polarimetric calibration method for NACO allow us to map the polarization in a region of 8"x25" (Ks) resp. 26"x28" (Lp). These are the first polarimetric observations of the GC in the Lp-band in 30 years, with vastly improved spatial resolution compared to previous results. This allows resolved polarimetry on bright bow-shock sources in this area for the first time at this wavelength.
4230. Near IR properties of Galaxy disks
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.