- ID:
- ivo://CDS.VizieR/J/A+A/586/A51
- Title:
- JK photometry of NGC 2808
- Short Name:
- J/A+A/586/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters are the oldest stellar systems in the Milky Way, and they probe the early epoch of the Galaxy formation. However, the uncertainties on their absolute age are still too large to soundly constrain how the Galactic structures have assembled. The aim of this work is to obtain an accurate estimate of the absolute age of the globular cluster NGC 2808 using deep IR data obtained with the multi-conjugate adaptive optics system operating at the Gemini South telescope (GeMS). This exquisite photometry, combined with that obtained in V and I-bands with HST, allowed us to detect the faint Main Sequence Knee feature in NGC 2808 colour magnitude diagram. The difference between this point and the main sequence turn-off is a good age estimator that provides ages with unprecedented accuracy.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/420/173
- Title:
- JK photometry of Omega Cen red giants
- Short Name:
- J/A+A/420/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IR catalogue of omega Cen is based on ground-based observations using SOFI (Infrared Spectrograph and Imaging Camera on the NTT telescope at ESO, La Silla) and contains about 73000 stars covering an area of 13"x13" around the center of the cluster. The limiting magnitude is K<=17.5m and the positional accuracy is better than 0.2"
- ID:
- ivo://CDS.VizieR/J/A+A/419/139
- Title:
- JK photometry on 5 Galactic globular clusters
- Short Name:
- J/A+A/419/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IR catalogs of the observed clusters are based on ground-based observations using the near-IR camera ARNICA@TNG equipped with a NICMOS-3 256x256 array detector. By using a magnification of 0.35"/px a total FoV of 1.5'x1.5' has been covered. The instrumental magnitudes have been calibrated into the Ferraro et al. (2000AJ....119.1282F) system. The catalogs for all the program clusters have been astrometrically corrected by using 2MASS catalogs, with an accuracy of <0.2arcsec.
- ID:
- ivo://CDS.VizieR/J/A+AS/135/83
- Title:
- JK'R magnitude of QSOs and around them
- Short Name:
- J/A+AS/135/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed a sample of 15 and 8 quasars with redshifts between 0.11 and 0.87 (mean value 0.38) in the J and K' bands respectively. Eleven of the quasars were previously known to be associated with extended emission line regions. After deconvolution of the image, substraction of the PSF when possible, and identification of companions with the help of HST archive images when available, extensions are seen for at least eleven quasars. However, average profiles are different from that of the PSF in only four objects, for which a good fit is obtained with an r^1/4^ law, suggesting that the underlying galaxies are ellipticals. Redshifts were available in the literature for surrounding objects in five quasar fields. For these objects, one to five companion galaxies were found. One quasar even belongs to a richness class 1 cluster. Most other quasars in our sample have nearby galaxies in projection which may also be companions. Environmental effects are therefore probably important to account for the properties of these objects.
- ID:
- ivo://CDS.VizieR/J/AJ/160/12
- Title:
- J, Ks, NUV emission of 133 red giant stars
- Short Name:
- J/AJ/160/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Main-sequence stars exhibit a clear rotation-activity relationship, in which rapidly rotating stars drive strong chromospheric/coronal ultraviolet and X-ray emission. While the vast majority of red giant stars are inactive, a few percent exhibit strong ultraviolet emission. Here we use a sample of 133 red giant stars observed by Sloan Digital Sky Survey APOGEE and Galaxy Evolution Explorer to demonstrate an empirical relationship between near-UV (NUV) excess and rotational velocity (vsini). Beyond this simple relationship, we find that NUV excess also correlates with rotation period and with Rossby number in a manner that shares broadly similar trends to those found in M dwarfs, including activity saturation among rapid rotators. Our data also suggest that the most extremely rapidly rotating giants may exhibit so-called supersaturation, which could be caused by centrifugal stripping of these stars rotating at a high fraction of breakup speed. As an example application of our empirical rotation-activity relation, we demonstrate that the NUV emission observed from a recently reported system comprising a red giant with a black hole companion is fully consistent with arising from the rapidly rotating red giant in that system. Most fundamentally, our findings suggest a common origin of chromospheric activity in rotation and convection for cool stars from main sequence to red giant stages of evolution.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/493/1075
- Title:
- JKs photometry of C stars in 2 nearby galaxies
- Short Name:
- J/A+A/493/1075
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Thousands of C stars have been identified in Local Group galaxies using narrow band photometry. To survey C stars at larger distances and alternative to the narrow-band approach is needed. We obtain, from ESO Archive data, NIR magnitudes and colours of previously known C stars in two dwarf irregular Local Group galaxies, namely IC 1613 and NGC 3109. We compare the NIR magnitudes and colours of the C star populations, previously identified from narrow band techniques to estimate the star formation history of their intermediate-age populations.
- 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.
1429. JKs photometry of N159A
- ID:
- ivo://CDS.VizieR/J/A+A/453/517
- Title:
- JKs photometry of N159A
- Short Name:
- J/A+A/453/517
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared imaging and spectroscopic observations of the HII region N159A (~10pc) in the giant star-forming region N159 (50pc) in the LMC. N159A was observed in the J and Ks bands at high spatial resolution ~0.2" using the ESO Very Large Telescope UT4 (VLT), equipped with the NAOS adaptative optics system. Our data reveal the morphology of this region in unprecedented detail. The protostar P2, one of the first YSOs of Class I identified in the LMC is now resolved in two YSO candidates. The ultracompact HII region LI-LMC 1501W is found to be a tight cluster embedded in a compact HII region ionised by a late O source. A new multiple system composed of a tight star cluster and an YSO candidate, all embedded in compact nebular region (0.4pc) is also detected at the north-east edge of N159A. The stellar population of the whole N159A region appears composed of two main stellar populations, one with an age <3Myr and the other one with a large range of age (300Myr-10Gyr). Using spectroscopy, one of the two exciting O stars in the HII region N159A is classified O5-O6.
- 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.
