- ID:
- ivo://CDS.VizieR/J/AJ/117/17
- Title:
- Hubble Deep Field near-IR obs.
- Short Name:
- J/AJ/117/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents data obtained during the NICMOS Guaranteed Time Observations of a portion of the Hubble Deep Field. The data are in a catalog format similar to the publication of the original WFPC2 Hubble Deep Field program (Williams et al., 1996, Cat. <J/AJ/112/1335>). The catalog contains 342 objects in a 49.1"x48.4" subfield of the total observed field, 235 of which are considered coincident with objects in the WFPC2 catalog. The 3{sigma} signal-to-noise ratio level is at an aperture AB magnitude of approximately 28.8 at 1.6{mu}m. The catalog sources, listed in order of right ascension, are selected to satisfy a limiting signal-to-noise ratio criterion of greater than or equal to 2.5. This introduces a few false detections into the catalog, and users should take careful note of the completeness and reliability levels for the catalog discussed in sections 9 and 10. The catalog also contains a test parameter indicating the results of half-catalog tests and the degree of coincidence with the original WFPC2 catalog.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/585/A7
- Title:
- Hyades single stars fiducial photometry
- Short Name:
- J/A+A/585/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Age and mass determinations for isolated stellar objects remain model-dependent. While stellar interior and atmospheric theoretical models are rapidly evolving, we need a powerful tool to test them. Open clusters are good candidates for this role. We aim to create a fiducial sequence of stellar objects for testing stellar and atmospheric models. We complement previous studies on the Hyades multiplicity by Lucky Imaging observations with the AstraLux Norte camera. This allows us to exclude possible binary and multiple systems with companions outside 2-7AU separation and to create a "single-star sequence" for the Hyades. The sequence encompasses 250 main-sequence stars ranging from A5V to M6V. Using the "Tool for Astrophysical Data Analysis" (TA-DA), we create various theoretical isochrones applying different combinations of interior and atmospheric models. We compare the isochrones with the observed Hyades single-star sequence on J vs. J-Ks, J vs. J-H and Ks vs. H-Ks color-magnitude diagrams. As a reference we also compute absolute fluxes and magnitudes for all stars from X-ray to mid-infrared based on photometric measurements available in the literature (ROSAT X-ray, GALEX UV, APASS gri, 2MASS JHKs, and WISE W1 to W4). We find that combinations of both PISA and DARTMOUTH stellar interior models with BT-Settl 2010 atmospheric models describe the observed sequence well. We use PISA in combination with BT-Settl 2010 models to derive theoretical predictions for physical parameters (Teff, mass, logg) of 250 single stars in the Hyades. The full sequence covers the mass range 0.13 to 2.3M_{sun}_, and effective temperatures between 3060K and 8200K. Conclusions. Within the measurement uncertainties, the current generation of models agree well with the single-star sequence. The primary limitations are the uncertainties in the measurement of the distance to individual Hyades members, and uncertainties in the photometry. Gaia parallaxes, photometry and spectroscopy will greatly reduce the uncertainties in particular at the lowest mass range, and will enable us to test model predictions with greater confidence. Additionally, a small (~0.05mag) systematic offset can be noted on J vs. J-K and K vs. H-K diagrams - the observed sequence is shifted to redder colors from the theoretical predictions.
- ID:
- ivo://CDS.VizieR/J/ApJ/818/39
- Title:
- Hydra I wide-field imaging and spectroscopy obs.
- Short Name:
- J/ApJ/818/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Eastern Banded Structure (EBS) and Hydra I halo overdensities are very nearby (d~10kpc) objects discovered in Sloan Digital Sky Survey (SDSS) data. Previous studies of the region have shown that EBS and Hydra I are spatially coincident, cold structures at the same distance, suggesting that Hydra I may be the EBS's progenitor. We combine new wide-field Dark Energy Camera (DECam) imaging and MMT/Hectochelle spectroscopic observations of Hydra I with SDSS archival spectroscopic observations to quantify Hydra I's present-day chemodynamical properties, and to infer whether it originated as a star cluster or dwarf galaxy. While previous work using shallow SDSS imaging assumed a standard old, metal-poor stellar population, our deeper DECam imaging reveals that Hydra I has a thin, well-defined main sequence turnoff of intermediate age (~5-6Gyr) and metallicity ([Fe/H]=-0.9dex). We measure statistically significant spreads in both the iron and alpha-element abundances of {sigma}_[Fe/H]_=0.13+/-0.02dex and {sigma}_[{alpha}/Fe]_=0.09+/-0.03dex, respectively, and place upper limits on both the rotation and its proper motion. Hydra I's intermediate age and [Fe/H] --as well as its low [{alpha}/Fe], apparent [Fe/H] spread, and present-day low luminosity-- suggest that its progenitor was a dwarf galaxy, which has subsequently lost more than 99.99% of its stellar mass.
- ID:
- ivo://CDS.VizieR/J/AJ/152/164
- Title:
- I-band light curves of OGLE LMC Miras
- Short Name:
- J/AJ/152/164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We develop a nonlinear semi-parametric Gaussian process model to estimate periods of Miras with sparsely sampled light curves. The model uses a sinusoidal basis for the periodic variation and a Gaussian process for the stochastic changes. We use maximum likelihood to estimate the period and the parameters of the Gaussian process, while integrating out the effects of other nuisance parameters in the model with respect to a suitable prior distribution obtained from earlier studies. Since the likelihood is highly multimodal for period, we implement a hybrid method that applies the quasi-Newton algorithm for Gaussian process parameters and search the period/frequency parameter space over a dense grid. A large-scale, high-fidelity simulation is conducted to mimic the sampling quality of Mira light curves obtained by the M33 Synoptic Stellar Survey. The simulated data set is publicly available and can serve as a testbed for future evaluation of different period estimation methods. The semi-parametric model outperforms an existing algorithm on this simulated test data set as measured by period recovery rate and quality of the resulting period-luminosity relations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/1753
- Title:
- I-band light curves of SNe II from OGLE-IV
- Short Name:
- J/MNRAS/449/1753
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study a sample of 11 Type II supernovae (SNe) discovered by the OGLE-IV survey. All objects have well-sampled I-band light curves, and at least one spectrum. We find that two or three of the 11 SNe have a declining light curve, and spectra consistent with other SNe II-L, while the rest have plateaus that can be as short as 70 d, unlike the 100 d typically found in nearby galaxies. The OGLE SNe are also brighter, and show that magnitude-limited surveys find SNe that are different than usually found in nearby galaxies. We discuss this sample in the context of understanding Type II SNe as a class and their suggested use as standard candles.
816. IC 4665
- ID:
- ivo://CDS.VizieR/J/AJ/105/1441
- Title:
- IC 4665
- Short Name:
- J/AJ/105/1441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a combined astrometric, photometric, and spectroscopic program to identify members of the open cluster IC 4665 are presented. Numerous new proper motion/photometric candidate members and at least 23 M dwarfs with H-alpha emission have been identified. A reanalysis of IC 4665's age using different methods yields conflicting results ranging from approx. 3x10^7^ yr to the age of the Pleiades. This study provides a list of candidate cluster members in the intermediate and low-mass regime of this cluster. Future spectroscopic observations of these candidates should eventually identify true cluster members. The results of new echelle observations of some candidates and the photometric monitoring of one apparent cluster member are given in an appendix.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A156
- Title:
- IC 4665 multi-band photometry
- Short Name:
- J/A+A/641/A156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Debris discs orbiting young stars are key to understand dust evolution and the planetary formation process.We take advantage of a recent membership analysis of the 30Myr nearby open cluster IC 4665 based on the Gaia and DANCe surveys to revisit the disc population of this cluster. We aim to study the disc population of IC 4665 using Spitzer (MIPS and IRAC) and WISE photometry. We use several colour-colour diagrams with empirical photospheric sequences to detect the sources with an infrared excess. Independently, we also fit the spectral energy distribution (SED) of our debris disc candidates with the Virtual Observatory SED analyser (VOSA) which is capable of automatically detecting infrared excesses and provides effective temperature estimates. We find six candidates debris disc host-stars (five with MIPS and one with WISE) and two of them are new candidates. We estimate a disc fraction of 24+/-10% for the B-A stars, where our sample is expected to be complete. This is similar to what has been reported in other clusters of similar ages (Upper Centaurus Lupus, Lower Centaurus Crux, the $\beta$ Pictoris moving group, and the Pleiades). For solar type stars we find a disk fraction of 9+/-9%, lower than that observed in regions with comparable ages. Our candidates debris disc host-stars are excellent targets to be studied with ALMA or the future James Webb Space Telescope (JWST).
- ID:
- ivo://CDS.VizieR/J/A+AS/126/81
- Title:
- IC 2602 VRI photometry
- Short Name:
- J/A+AS/126/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of VRI photometry of the young open cluster IC 2602. Two 15x15arcmin^2^ fields were observed in February and May 1991 using the 1-m Swope telescope at Las Campanas. Using theoretical isochrones obtained from D'Antona & Mazzitelli (1994ApJS...90..467D), and allowing for observational and other uncertainties, we identify 78 primary candidate members with 12<V<18.5 from their positions on colour-magnitude diagrams. We compare the cluster field with an offset field of similar galactic latitude and estimate the contamination due to background stars to be large, >=50%, as might be expected given its low galactic latitude. We also compare our photometry with that given for the X-ray detected stars of Randich et al. (1995A&A...300..134R) present complimentary narrow band H{alpha} photometry for a subset of the stars.
819. IC1805 YSOs
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/2684
- Title:
- IC1805 YSOs
- Short Name:
- J/MNRAS/468/2684
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- W4 is a giant HII region ionized by the OB stars of the cluster IC 1805. The HII region/cluster complex has been a subject of numerous investigations as it is an excellent laboratory for studying the feedback effect of massive stars on the surrounding region. However, the low-mass stellar content of the cluster IC 1805 remains poorly studied till now. With the aim to unravel the low-mass stellar population of the cluster, we present the results of a multiwavelength study based on deep optical data obtained with the Canada-France-Hawaii Telescope, infrared data from Two Micron All Sky Survey and SpitzerSpace Telescope and X-ray data from ChandraSpace Telescope. The present optical data set is complete enough to detect stars down to 0.2M_{sun}_, which is the deepest optical observation so far for the cluster. We identified 384 candidate young stellar objects (YSOs; 101 Class I/II and 283 Class III) within the cluster using various colour-colour and colour-magnitude diagrams. We inferred the mean age of the identified YSOs to be ~2.5Myr and mass in the range 0.3-2.5M_{sun}_. The mass function of our YSO sample has a power-law index of -1.23+/-0.23, close to the Salpeter value (-1.35), and consistent with those of other star-forming complexes. We explored the disc evolution of the cluster members and found that the disc-less sources are relatively older compared to the disc bearing YSO candidates. We examined the effect of high-mass stars on the circumstellar discs and within uncertainties, the influence of massive stars on the disc fraction seems to be insignificant. We also studied the spatial correlation of the YSOs with the distribution of gas and dust of the complex to conclude that IC 1805 would have formed in a large filamentary cloud.
- ID:
- ivo://CDS.VizieR/J/AJ/158/16
- Title:
- Identification of RR Lyrae stars from the DES
- Short Name:
- J/AJ/158/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many studies have shown that RR Lyrae variable stars (RRL) are powerful stellar tracers of Galactic halo structure and satellite galaxies. The Dark Energy Survey (DES), with its deep and wide coverage (g~23.5 mag in a single exposure; over 5000 deg^2^) provides a rich opportunity to search for substructures out to the edge of the Milky Way halo. However, the sparse and unevenly sampled multiband light curves from the DES wide-field survey (a median of four observations in each of grizY over the first three years) pose a challenge for traditional techniques used to detect RRL. We present an empirically motivated and computationally efficient template-fitting method to identify these variable stars using three years of DES data. When tested on DES light curves of previously classified objects in SDSS stripe 82, our algorithm recovers 89% of RRL periods to within 1% of their true value with 85% purity and 76% completeness. Using this method, we identify 5783 RRL candidates, ~28% of which are previously undiscovered. This method will be useful for identifying RRL in other sparse multiband data sets.
