- 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.
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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/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/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.
- ID:
- ivo://CDS.VizieR/J/AJ/138/1003
- Title:
- IR photometry of massive LMC stars
- Short Name:
- J/AJ/138/1003
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 1750 massive stars in the Large Magellanic Cloud (LMC), with accurate spectral types compiled from the literature, and a photometric catalog for a subset of 1268 of these stars, with the goal of exploring their infrared properties. The photometric catalog consists of stars with infrared counterparts in the Spitzer SAGE survey database, for which we present uniform photometry from 0.3 to 24um in the UBVIJHKs+IRAC+MIPS24 bands. The resulting infrared color-magnitude diagrams illustrate that the supergiant B[e], red supergiant, and luminous blue variable (LBV) stars are among the brightest infrared point sources in the LMC, due to their intrinsic brightness, and at longer wavelengths, due to dust. We detect infrared excesses due to free-free emission among ~900 OB stars, which correlate with luminosity class. We confirm the presence of dust around 10 supergiant B[e] stars, finding the shape of their spectral energy distributions (SEDs) to be very similar, in contrast to the variety of SED shapes among the spectrally variable LBVs. The similar luminosities of B[e] supergiants (log L/L_{sun}_>=4) and the rare, dusty progenitors of the new class of optical transients (e.g., SN 2008S and NGC 300 OT), plus the fact that dust is present in both types of objects, suggests a common origin for them. We find the infrared colors for Wolf-Rayet stars to be independent of spectral type and their SEDs to be flatter than what models predict.
- ID:
- ivo://CDS.VizieR/J/AJ/140/416
- Title:
- IR photometry of massive stars in the SMC
- Short Name:
- J/AJ/140/416
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 5324 massive stars in the Small Magellanic Cloud (SMC), with accurate spectral types compiled from the literature, and a photometric catalog for a subset of 3654 of these stars, with the goal of exploring their infrared properties. The photometric catalog consists of stars with infrared counterparts in the Spitzer SAGE-SMC survey database, for which we present uniform photometry from 0.3 to 24um in the UBVIJHKs+IRAC+MIPS24 bands.
- ID:
- ivo://CDS.VizieR/J/ApJ/657/1013
- Title:
- IR photometry of 2MASS/Spitzer white dwarfs
- Short Name:
- J/ApJ/657/1013
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We review the available near- and mid-infrared photometry for white dwarfs obtained from the Two Micron All Sky Survey (2MASS) and by the Spitzer Space Telescope. Both data sets have recently been used to seek white dwarfs with infrared excesses due to the presence of unresolved companions or circumstellar disks, and also to derive the atmospheric parameters of cool white dwarfs. We first attempt to evaluate the reliability of the 2MASS photometry by comparing it with an independent set of published JHK CIT magnitudes for 160 cool white dwarf stars, and also by comparing the data with the predictions of detailed model atmosphere calculations. The possibility of using 2MASS to identify unresolved M dwarf companions or circumstellar disks is then discussed.
