- ID:
- ivo://CDS.VizieR/J/A+A/436/853
- Title:
- IR photometry of Alpha Per low-mass members
- Short Name:
- J/A+A/436/853
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a near-infrared (K'-band) survey of 0.7 square degree area in the {alpha} Persei open cluster (age=90Myr, distance=182pc) carried out with the Omega-Prime camera on the Calar Alto 3.5-m telescope. Combining optical data (Rc and Ic) obtained with the KPNO/MOSA detector and presented in Stauffer et al. (1999ApJ...527..219S; S99) with the K' observations, a sample of new candidate members has been extracted from the optical-infrared colour-magnitude diagram. The location of these candidates in the colour-colour diagram suggests that two-thirds of them are actually reddened background giants. About 20 new candidate members with masses between 0.3 and 0.04M_{sun}_ are added to the ~400 known Alpha Per cluster members. If they are indeed Alpha Per members, four of the new candidates would be brown dwarfs. We discuss the advantages and drawbacks of the near-infrared survey as compared to the optical selection method. We also describe the outcome of optical spectroscopy obtained with the Twin spectrograph on the Calar Alto 3.5-m telescope for about 30 candidates, including selected members from the optical sample presented in Barrado y Navascues et al. (2002, Cat. <J/A+A/395/813>) and from our joint optical/infrared catalogue. These results argue in favour of the optical selection method for this particular cluster.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/642/972
- Title:
- IR photometry of a star-forming core in NGC 2264
- Short Name:
- J/ApJ/642/972
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze Spitzer and Magellan observations of a star-forming core near IRS 2 in the young cluster NGC 2264. The submillimeter source IRAS 12 S1, previously believed to be an intermediate-mass Class 0 object is shown to be a dense collection of embedded, low-mass stars. We argue that this group of stars represents the fragmenting collapse of a dense, turbulent core, using a number of indicators of extreme youth. With reasonable estimates for the velocity dispersion in the group, we estimate a dynamical lifetime of only a few times 10^4^yr. Spectral energy distributions of stars in the core are consistent with Class I or Class 0 assignments. We present observations of an extensive system of molecular hydrogen emission knots. The luminosity of the objects in the core region are consistent with roughly solar mass protostars.
- ID:
- ivo://CDS.VizieR/J/A+AS/119/547
- Title:
- IR photometry of ESO calibration stars
- Short Name:
- J/A+AS/119/547
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the infrared (IR) photometric system for the single channel photometers at ESO, which have been used from 1983 until 1994. In addition to the broadband near infrared (NIR, 1-5{mu}m) photometric system presented in 1991 by Bouchet et al. and Bersanelli et al., we describe a narrow-band NIR photometric system and a mid infrared (MIR, 7-20{mu}m) photometric system. We also extend the set of NIR standard stars by Bouchet et al. towards fainter objects (K=~9). The photometric data of the standard stars in these systems were extracted from the complete IR photometric data archive of ESO, covering 10 years. The zeropoints of the NIR photometry are set by assuming that HR 3314 has a V-magnitude of 3.89, and that V-K=-0.05, J-K=-0.01, H-K=-0.01, K-L'=0.00, K-M=0.00. The zeropoints of the MIR photometry are set by assuming that the colours of{beta} Hyi (HR 0098) and {alpha} CenA (HR 5459) are equal to the colours of the Sun. We adopt the absolute calibration of Megessier (1995A&A...296..771M) for the NIR and we argue that this calibration can be extrapolated to 20{mu}m, using the MIR calibrations by Rieke et al. (1985AJ.....90..900R) and Cohen et al. (1992AJ....104.1650C). The definition of the zeropoints is consistent with the absolute calibration. We obtained accurate ({sigma}=~0.02mag.) NIR photometry of about 240 standard stars and MIR photometry of about 40 standard stars ({sigma}=~0.04mag). Comparison of our NIR photometric system with other well established systems shows that there are some small colour dependencies and zeropoint offsets which are always smaller than about 0.02mag. except for the L' band.
- ID:
- ivo://CDS.VizieR/J/AJ/158/105
- Title:
- IR photometry of field RR Lyrae variable stars
- Short Name:
- J/AJ/158/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-epoch infrared photometry in the K_s_-band for 74 bright RR Lyrae variable stars tied directly to the Two-Micron All-Sky Survey (2MASS) photometric system. We systematize additional K-band photometry from the literature to the 2MASS system and combine it to obtain photometry for 146 RR Lyrae stars on a consistent, modern system. A set of outlier stars in the literature photometry is identified and discussed. Reddening estimates for each star are gathered from the literature and combined to provide an estimate of the interstellar absorption affecting each star, and we find excellent agreement with another source in the literature. We utilize trigonometric parallaxes from the Second Data Release of the European Space Agency's Gaia astrometric satellite to determine the absolute magnitude, M_Ks_ for each of these stars, and analyze them using the astrometry-based luminosity prescription to obtain a parallax-based calibration of M_K_ (RR). Our period-luminosity-metallicity relationship is M_Ks_=(-2.8+/-0.2)(logP+0.27)+(0.12+/-0.02) ([Fe/H]+1.3)-(0.41+/-0.03) mag. A Gaia global zero-point error of {pi}_zp_=-0.042+/-0.013 mas is determined for this sample of RR Lyrae stars.
- ID:
- ivo://CDS.VizieR/J/PAZh/27/393
- Title:
- IR photometry of five long-period binaries
- Short Name:
- J/PAZh/27/393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- JHKLM photometry for five long-period binaries is presented. For a description of the UBVR and JHKLM photometric systems, see e.g. <GCPD/08> and <GCPD/09> respectively.
- ID:
- ivo://CDS.VizieR/J/MNRAS/351/1204
- Title:
- IR Photometry of 10 Galactic Globular Clusters
- Short Name:
- J/MNRAS/351/1204
- 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 IRAC2@ESO/MPI 2.2m equipped with a NICMOS-3 256x256 array detector. By using two different magnifications: 0.28"/pix and 0.51"/pix a total FoV of 4'x4' has been covered. The instrumental magnitudes have been calibrated into the 2MASS photometric system and astrometrically corrected by using 2MASS catalogs, with an accuracy of <0.2arcsec.
- ID:
- ivo://CDS.VizieR/J/ApJ/597/555
- Title:
- IR photometry of IC 348 young brown dwarfs
- Short Name:
- J/ApJ/597/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a population of young brown dwarf candidates in the open star cluster IC 348 and the development of a new spectroscopic classification technique using narrowband photometry. Observations were made using FLITECAM, the First Light Camera for SOFIA, at the 3m Shane telescope at Lick Observatory. FLITECAM is a new 1-5{mu}m camera with an 8' field of view. Custom narrowband filters were developed to detect absorption features of water vapor (at 1.495{mu}) and methane (at 1.66{mu}m) characteristic of brown dwarfs. These filters enable spectral classification of stars and brown dwarfs without spectroscopy.
- ID:
- ivo://CDS.VizieR/J/A+A/318/879
- Title:
- IR photometry of L1551/IRS5
- Short Name:
- J/A+A/318/879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a new approach to the solution of the frequency-dependent stationary radiative transfer equation for axially-symmetric circumstellar dust disks. The method is applied to flared disks which are considered here as spheres with the polar cones removed. We have simplified the problem by computing the moments of the specific intensity only for the midplane and the surface of the flared disk. At the same time, we solve the radiative transfer equation exactly for an "equivalent" spherical envelope. The basic assumption is that density distribution in the disk depends only on the radial distance from the central star. This results in significantly faster calculations, reduces necessary computer memory, and allows incorporation of the algorithm into a hydrodynamical code. We applied our fast 2D radiative transfer code to a detailed modeling of the deeply embedded young stellar object (YSO) L1551 IRS 5. This is a YSO in the Taurus-Aurigae star-forming region, which has been very well studied with good spatial resolution and photometric data over the wide range from ultraviolet to millimeter wavelengths. Exploring the parameter space of our axially-symmetric models, we have found a self-consistent solution for L1551 IRS 5 explaining all available infrared and submm/mm continuum observations. Here, Appendices A, B, and C are presented, which are not available in the journal version of the paper. In Appendices A and B, one can find more details on the method and the overall iterative numerical scheme. Appendix C (Table C1) lists all published photometric observations of L1551 IRS 5, which we have found in the literature and which have been used in our modeling.
- ID:
- ivo://CDS.VizieR/J/AJ/99/784
- Title:
- IR photometry of LMC long-period variables
- Short Name:
- J/AJ/99/784
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared JHK photometry and visual spectra have been obtained for a large sample of long-period variables (LPVs) in the Large Magellanic Cloud (LMC). Various aspects of the asymptotic giant branch (AGB) evolution of LPVs are discussed using these data. The birth/death rate of LPVs of different ages in the LMC is compared with the birth rates of appropriate samples of planetary nebulae clump stars, Cepheids, and OH/IR stars. It appears that there are much fewer large-amplitude LPVs per unit galactic stellar mass in the LMC than in the Galaxy. We suggest that this may be due to the fact that the evolved intermediate-age AGB stars in the LMC often turn into carbon stars, which tend to have smaller pulsation amplitudes than M stars. There is also a major discrepancy between the number of LPVs in the LMC (and in the Galaxy) and the number predicted by the theories of AGB evolution, pulsation, and mass loss. A distance modulus to the LMC of 18.66+0.05 is derived by comparing the LMC LPVs with P~200days with the 47 Tucanae Mira variables in the (K, logP) plane. The (K, logP) relation is also used to examine the tilt of the LMC populations of old and intermediate-age stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/631
- Title:
- IR photometry of LMC O-rich evolved stars
- Short Name:
- J/MNRAS/440/631
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to determine the composition of the dust in the circumstellar envelopes of oxygen-rich asymptotic giant branch (AGB) stars, we have computed a grid of MODUST radiative-transfer models for a range of dust compositions, mass-loss rates, dust-shell inner radii and stellar parameters. We compare the resulting colours with the observed oxygen-rich AGB stars from the SAGE-Spec Large Magellanic Cloud (LMC) sample, finding good overall agreement for stars with a mid-infrared excess. We use these models to fit a sample of 37 O-rich AGB stars in the LMC with optically thin circumstellar envelopes, for which 5-35{mu}m Spitzer infrared spectrograph (IRS) spectra and broad-band photometry from the optical to the mid-infrared are available. From the modelling, we find mass-loss rates in the range ~8x10^-8^-5x10^-6^M_{sun}_/yr, and we show that a grain mixture consisting primarily of amorphous silicates, with contributions from amorphous alumina and metallic iron, provides a good fit to the observed spectra. Furthermore, we show from dust models that the AKARI [11]-[15] versus [3.2]-[7] colour-colour diagram is able to determine the fractional abundance of alumina in O-rich AGB stars.
