- ID:
- ivo://CDS.VizieR/J/A+A/390/511
- Title:
- Millimetre observations of carbon stars. II.
- Short Name:
- J/A+A/390/511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dust- and gas mass loss rates and distances are determined for a sample of about 330 infra-red carbon stars that probe a distance up to about 5.5kpc. The dependence of the dust- and gas mass loss rates, and the expansion velocity upon galactic longitude (l) are studied. It is found that the expansion velocity significantly depends on l, but that the absolute bolometric magnitude, the dust mass loss rate and the gas-to-dust ratio depend on l marginally, if at all, and the gas mass loss rate does not depend on l. Beyond the solar circle, the expansion velocity (as well as the luminosity, dust-to-gas ratio, dust mass loss rate) is lower than inside the solar circle, as expected from the overall gradient in metallicity content of the Galaxy. Combining the average expansion velocity inside and beyond the solar circle with the theoretically predicted relation between expansion velocity and gas-to-dust ratio, we find that the metallicity gradient in the solar neighbourhood is about -0.034dex/kpc, well within the quoted range of values in the literature.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/142/181
- Title:
- 2mm molecular line survey of IRC+10 216
- Short Name:
- J/A+AS/142/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mm-wave spectrum of the C-star envelope IRC+10 216 has been continuously surveyed between 129.0 and 172.5GHz with the IRAM 30-m telescope. 380 lines are detected, of which 317 have been identified. The identified lines arise from 30 different molecules and radicals which, in their vast majority, are not observed in hot and dense interstellar clouds such as Orion A or W3(OH). Actually, half of the molecular species identified in the mm-wave spectrum of IRC+10216 were first observed in the course of this spectral survey.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A105
- Title:
- Modelisation of AGB stars in the LMC
- Short Name:
- J/A+A/537/A105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asymptotic giant branch (AGB) stars are major contributors to both the chemical enrichment of the interstellar medium and the integrated light of galaxies. Despite its importance, the AGB is one of the least understood phases of stellar evolution. The main difficulties associated with detailed modelling of the AGB are related to the mass-loss process and the 3rd dredge-up efficiency. We provide direct measures of mass-loss rates and luminosities for a complete sample of AGB stars in the Large Magellanic Cloud, disentangling the C- and O-rich stellar populations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/355/1196
- Title:
- MS bands of SiC_2_ in LMC carbon stars
- Short Name:
- J/MNRAS/355/1196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a sample of 304 carbon stars in the central parts of the Large Magellanic Cloud (LMC), ~27 per cent have Merrill-Sanford (MS) bands of the SiC2 molecule. The data are based on a uniform set of spectra taken with 2dF on the Anglo-Australian Telescope, and give useful statistics on the incidence of MS bands and on their correlation (or otherwise) with other properties. All of these are red stars, cooler than 3100 K. The proportion of stars showing the bands is highest amongst the coolest stars, but not all very cool stars show the bands. There is no evidence that MS bands are more common in J-type stars (carbon stars with a high ^13^C/^12^C ratio) than in N-type carbon stars, at least within this sample of LMC stars. There is no apparent correlation with stellar variability, or between the photospheric temperature [as measured by (J-K)] and the occurrence of the 'hot' MS bands from excited molecular states.
- ID:
- ivo://CDS.VizieR/J/A+A/466/1099
- Title:
- N-band visibilities of V Oph
- Short Name:
- J/A+A/466/1099
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first multi-epoch N-band spectro-interferometric observations of the carbon-rich Mira variable V Oph using MIDI at the ESO's Very Large Telescope Interferometer. Our aim is to study temporal variations of physical properties of the outer atmosphere and the circumstellar dust shell based on spectrally-dispersed N-band visibilities over the C_2_H_2_ (+HCN) features and the dust emission.
- ID:
- ivo://CDS.VizieR/J/MNRAS/369/751
- Title:
- Near-infrared photometry of carbon stars
- Short Name:
- J/MNRAS/369/751
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-infrared, JHKL, photometry of 239 Galactic C-rich variable stars is presented and discussed. From these and published data, the stars were classified as Mira or non-Mira variables, and amplitudes and pulsation periods, ranging from 222 to 948d for the Miras, were determined for most of them. A comparison of the colour and period relations with those of similar stars in the Large Magellanic Cloud indicates minor differences, which may be the consequence of sample selection effects. Apparent bolometric magnitudes were determined by combining the mean JHKL fluxes with mid-infrared photometry from IRAS and MSX.
- 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.
- 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.
- 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.
- 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.
