Search

Start Over Subject galaxies
1891. JHKs photometry of AGB stars in NGC 6822
ID:
ivo://CDS.VizieR/J/MNRAS/428/2216
Title:
JHKs photometry of AGB stars in NGC 6822
Short Name:
J/MNRAS/428/2216
Date:
21 Oct 2021
Publisher:
CDS
Description:
JHKs photometry is presented from a 3.5yr survey of the central regions of the irregular galaxy NGC 6822. The morphology of the colour-magnitude and colour-colour diagrams is discussed with particular reference to M-, S- and C-type asymptotic giant branch (AGB) stars and to M supergiants. Mean JHKs magnitudes and periods are given for 11 O-rich and 50 presumed C-rich Miras. Data are also listed for 27 large-amplitude AGB stars without periods and for 69 small-amplitude AGB variables. The slope of the bolometric period-luminosity relation for the C-rich Miras is in good agreement with that in the Large Magellanic Cloud. Distance moduli derived from the C- and O-rich Miras are in agreement with other estimates. The period distribution of C-rich Miras in NGC 6822 is similar to that in the Magellanic Clouds, but differs from that in the dwarf spheroidals in the Local Group. In the latter there is a significant proportion of large-amplitude, short-period variables indicating a population producing old carbon-rich AGB stars.
1892. JHKs photometry of LeoII dSph giants
ID:
ivo://CDS.VizieR/J/MNRAS/388/1185
Title:
JHKs photometry of LeoII dSph giants
Short Name:
J/MNRAS/388/1185
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of the evolved stellar populations in the dwarf spheroidal galaxy Leo II, based on JHKs observations obtained with the near-infrared array WFCAM at the UKIRT telescope. Combining the new data with optical data, we derived photometric estimates of the distribution of global metallicity [M/H] of individual red giant stars from their V-Ks colours. Our results are consistent with the metallicities of red giant branch (RGB) stars obtained from CaII triplet spectroscopy, once the age effects are considered.
1893. JHKs photometry of LPVs in M33
ID:
ivo://CDS.VizieR/J/A+A/487/131
Title:
JHKs photometry of LPVs in M33
Short Name:
J/A+A/487/131
Date:
21 Oct 2021
Publisher:
CDS
Description:
Wide-field JHKs near-infrared observations covering an area of 1.8x1.8deg^2^ centred on M33 were obtained using WFCAM at UKIRT. These data show a large population of intermediate-age asymptotic giant branch stars (AGB). We have used both C-type and M-type AGB stars to determine spatial variations in metallicity and mean age across the galaxy. We distinguished between C-type and M-type AGB stars from their location in the colour-magnitude diagram (J-Ks, Ks). The distribution of these stars is supported by a cross-identification between our sample and a catalogue of optically confirmed, long-period variable stars, as well as with the list of sources detected by Spitzer in the mid-infrared. We calculated the C/M ratio and the orientation of the galaxy in the sky, and compared the Ks magnitude distribution with theoretical distributions spanning a range of metallicities and star formation rates (SFRs). The C/M ratio surface map confirms a metallicity gradient in the galaxy corresponding to a spread in [Fe/H]=0.6dex with substructures in the inner and outer galaxy. Magnitude and colour variations suggest orientation and extinction effects on the galaxy disc. Maps showing the distribution of mean age and metallicity obtained from the Ks method suggest that: the outer galaxy disc/halo is metal poorer than the nuclear region and metal-rich clumps in the inner galaxy change location with time. The average outer ring and nuclear stellar population is ~6Gyr old while central regions are a few Gyr younger.
1894. JHKs photometry of Sculptor dSph galaxy
ID:
ivo://CDS.VizieR/J/MNRAS/414/3492
Title:
JHKs photometry of Sculptor dSph galaxy
Short Name:
J/MNRAS/414/3492
Date:
21 Oct 2021
Publisher:
CDS
Description:
JHKs photometry is presented for a 35 arcmin^2^ field centred on the Sculptor dwarf spheroidal galaxy. With the aid of published kinematic data definite galaxy members are identified and the width in J-K of the colour-magnitude diagram is shown to be consistent with an old population of stars with a large range in metal abundance. We identify two Asymptotic Giant Branch variables, both carbon Miras, with periods of 189 and 554d, respectively, and discuss their ages, metallicities and mass-loss as well as their positions in the Mira period-luminosity diagram. There is evidence for a general period-age relation for Local Group Miras. The mass-loss rate for the 554d variable, MAG29, appears to be consistent with that found for Miras of comparable period in other Local Group galaxies.
1895. JHK variable stars in M33
ID:
ivo://CDS.VizieR/J/MNRAS/411/263
Title:
JHK variable stars in M33
Short Name:
J/MNRAS/411/263
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M 33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. The most extensive dataset was obtained in the K-band with the UIST instrument for the central 4'x4' (1kpc^2^) --- this contains the nuclear star cluster and inner disc. These data, taken during the period 2003-2007, were complemented by J- and H-band images. Photometry was obtained for 18,398 stars in this region; of these, 812 stars were found to be variable, most of which are Asymptotic Giant Branch (AGB) stars. Our data were matched to optical catalogues of variable stars and carbon stars, and to mid-infrared photometry from the Spitzer Space Telescope. In this first of a series of papers, we present the methodology of the variability survey and the photometric catalogue, which is made publicly available at the Centre de Donnees astronomiques de Strasbourg (CDS), and discuss the properties of the variable stars. Most dusty AGB stars had not been previously identified in optical variability surveys, and our survey is also more complete for these types of stars than the Spitzer survey.
1896. JK photometry in SA 57-6575, Her 1-5677 fields
ID:
ivo://CDS.VizieR/J/ApJ/505/50
Title:
JK photometry in SA 57-6575, Her 1-5677 fields
Short Name:
J/ApJ/505/50
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the Keck 10m telescope to count objects as a function of image size in two high Galactic latitude fields covering 1.5arcmin^2^ and reaching 50% completeness depths of K=24 and J=24.5 for stellar sources. Our counts extend ~1mag deeper in K than those of surveys with other telescopes; complement other Keck surveys in the K-band that provide counts at comparable or shallower depths but that have not utilized image structure; and extend by several magnitudes the J-band counts from brighter surveys using smaller telescopes that cover larger areas.
1897. JKs, i'g'r' photometry of C stars in NGC 6822
ID:
ivo://CDS.VizieR/J/A+A/456/905
Title:
JKs, i'g'r' photometry of C stars in NGC 6822
Short Name:
J/A+A/456/905
Date:
21 Oct 2021
Publisher:
CDS
Description:
From a 2{deg}x2{deg} survey of NGC 6822 we have previously established that this Local Group dwarf irregular galaxy possesses a huge spheroid having more than one degree in length. This spheroid is in rotation but its rotation curve is known only within ~15' from the center. It is therefore critical to identify bright stars belonging to the spheroid to characterize, as far as possible, its outer kinematics. We use the new wide field near infrared imager CPAPIR, operated by the SMARTS consortium, to acquire J, K_s_ images of two 34.8'x34.8' areas in the outer spheroid to search for C stars. The colour diagram of the fields allows the identification of 192 C stars candidates but a study of the FWHM of the images permits the rejection of numerous non-stellar objects with colours similar to C stars. We are left with 75 new C stars, their mean K_s_ magnitude and mean colour are similar to the bulk of known NGC 6822 C stars. This outer spheroid survey confirms that the intermediate-age AGB stars are a major contributor to the stellar populations of the spheroid. The discovery of some 50 C stars well beyond the limit of the previously known rotation curve calls for a promising spectroscopic follow-up to a major axis distance of 40'.
1898. JKs photometry of C stars in IC10 and WLM
ID:
ivo://CDS.VizieR/J/A+A/474/35
Title:
JKs photometry of C stars in IC10 and WLM
Short Name:
J/A+A/474/35
Date:
21 Oct 2021
Publisher:
CDS
Description:
The selection of AGB C and M stars from NIR colours has been done in recent years using adjustable criteria that are in needs of standardization if one wants to compare, in a coherent manner, properties of various populations. We intend to assess the NIR colour technique to identify C and M stars. We compare the NIR colours of several C stars previously identified from spectroscopy or narrow band techniques in WLM, IC 10 and NGC 6822. We demonstrate that very few M stars have (J-K)_0_>1.4 but a non negligible number of C stars are bluer than this limit. Thus, counts of M and C stars based on such limit do not produce pure samples. C/M ratios determined from NIR colours must be regarded as underestimates mainly because the M numbers include many warm C stars and also K stars if no blue limit is considered.
1899. JKs photometry of local universe galaxies
ID:
ivo://CDS.VizieR/J/ApJS/149/327
Title:
JKs photometry of local universe galaxies
Short Name:
J/ApJS/149/327
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents empirical results from a deep imaging survey of galaxies in the local universe at the J and Ks wavelengths. Three hundred ninety-one images have been obtained and calibrated using the same camera and filter set with the Steward Observatory 1.6m Kuiper Telescope on Mount Bigelow and the 2.3m Bok Telescope on Kitt Peak. The limiting magnitude is typically 22mag/arcsec at J and 21mag/arcsec at Ks. The central surface brightness, apparent magnitudes, sizes, scale lengths, and inclinations are tabulated from measurements made using these data. The purpose of this paper is to provide basic near-infrared data on a variety of galaxy types.
1900. JKs photometry of WLM galaxy carbon stars
ID:
ivo://CDS.VizieR/J/A+A/466/501
Title:
JKs photometry of WLM galaxy carbon stars
Short Name:
J/A+A/466/501
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify the rich carbon star population of the Magellanic-type dwarf irregular galaxy WLM (Wolf-Lundmark-Melotte) and study its photometric properties from deep near-IR observations. The galaxy also exhibits a clear presence of oxygen-rich population. We derive a carbon to M-star ratio of C/M=0.56+/-0.12, relatively high in comparison with many galaxies. The spatial distribution of the AGB stars in WLM hints at the presence of two stellar complexes with a size of a few hundred parsecs. Using the HI map of WLM and the derived gas-to-dust ratio for this galaxy N(HI)/E(B-V)=60+/-10[10^21^at/cm^2^/mag] we re-determined the distance modulus of WLM from the IR photometry of four known Cepheids, obtaining (m-M)0=24.84+/-0.14mag. In addition, we determine the scale length of 0.75+/-0.14kpc of WLM disk in the J-band.

Limit your search

more »

more »

more »

more »

  • 24,330
  • 11