- ID:
- ivo://CDS.VizieR/J/ApJS/191/389
- Title:
- Photometric monitoring in {sigma} Ori cluster
- Short Name:
- J/ApJS/191/389
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-precision photometry on 107 variable low-mass stars and brown dwarfs in the ~3Myr {sigma} Orionis open cluster. We have carried out I-band photometric monitoring within two fields, encompassing 153 confirmed or candidate members of the low-mass cluster population, from 0.02 to 0.5M_{sun}_. We are sensitive to brightness changes on timescales from 10 minutes to two weeks with amplitudes as low as 0.004mag, and find variability on these timescales in nearly 70% of cluster members. We identify both periodic and aperiodic modes of variability, as well as semi-periodic rapid fading events that are not accounted for by the standard explanations of rotational modulation of surface features or accretion. We have incorporated both optical and infrared color data to uncover trends in variability with mass and circumstellar disks.
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- ID:
- ivo://CDS.VizieR/J/A+AS/140/29
- Title:
- Photometric monitoring of 47 late-type stars
- Short Name:
- J/A+AS/140/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present continuous multicolor photometry for 47 stars from October 1996 through June 1997. Altogether, 7073 V(RI)_c_, UBV, and by data points, each the average of three individual readings, were acquired with three automatic photoelectric telescopes (APTs) at Fairborn Observatory in southern Arizona. Most of our targets are chromospherically active single and binary stars of spectral type G to K but there are also four pre-main-sequence objects and three pulsating stars in our sample. The light variability is generally due to rotational modulation of an asymmetrically spotted stellar surface and therefore precise rotational periods and their seasonal variations are determined from Fourier analysis. We also report on photometric variations of {gamma} CrB (A0V) with a period of 0.44534 days. All data are available in numerical form.
- ID:
- ivo://CDS.VizieR/J/ApJ/901/169
- Title:
- Photometric obs. & LAMOST sp. of 4 W UMa binaries
- Short Name:
- J/ApJ/901/169
- Date:
- 22 Feb 2022 00:36:07
- Publisher:
- CDS
- Description:
- We present new photometric data and LAMOST spectra for the W UMa binaries UV Lyn, V781 Tau, NSVS 4484038, and 2MASS J15471055+5302107. The orbital and starspot parameters are obtained using the Wilson-Devinney program. Comparing the starspot parameters at different times, there are magnetic activities in these four binaries. The orbital period of UV Lyn is increasing at a rate of dP/dt=+8.9(5)x10^-8^d/yr, which maybe due to mass transfer from the less massive component to the more massive component (dM1/dt=-6.4x10^-8^M_{sun}_/yr). The period variation of 2MASSJ15471055+5302107 is also increasing at a rate of 6.0(4)x10^-7^d/yr, which can be explained by mass transfer from the less massive component to the more massive component (dM1/dt=-2.8x10^-7^M_{sun}_/yr). The period variation of V781 Tau presents the downward parabola superimposed the cyclic oscillation. The period of V781 Tau is decreasing (dP/dt=-3.2(4)x10^-8^d/yr), which can be explained by mass transfer from the more massive component to the less massive component (dM2/dt=-2.2x10^-8^M_{sun}_/yr). The cyclic oscillation may be due to the magnetic activity with a period of 30.8(5)yr rather than a third body. The period variation of NSVS4484038 also shows the cyclic oscillation, which could be explained by the magnetic activity with 10.8(1)yr or a black hole candidate. Interestingly, there is a depth variation between the light minimum times of NSVS 4484038, which may also be caused by stellar magnetic activity.
- ID:
- ivo://CDS.VizieR/J/ApJ/704/548
- Title:
- Photometric properties of galaxies at z=4-6
- Short Name:
- J/ApJ/704/548
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new information on galaxies in the vicinity of luminous radio galaxies (RGs) and quasars at z~4, 5, and 6. These fields were previously found to contain overdensities of Lyman Break Galaxies (LBGs) or spectroscopic Ly{alpha} emitters (LAEs), which were interpreted as evidence for clusters-in-formation ("protoclusters"). We use Hubble Space Telescope and Spitzer data to infer stellar masses from stellar synthesis models calibrated against the Millennium Run simulations, and contrast our results with large samples of LBGs in more average environments as probed by the Great Observatories Origins Deep Survey (GOODS).
- ID:
- ivo://CDS.VizieR/J/ApJ/871/233
- Title:
- Photometric redshifts in the EGOODS-North field
- Short Name:
- J/ApJ/871/233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep J- and H-band images in the extended Great Observatories Origins Deep Survey-North field covering an area of 0.22deg^2^. The observations were taken using WIRCam on the 3.6m Canada-France-Hawaii Telescope. Together with the reprocessed Ks-band image, the 5{sigma} limiting AB magnitudes (in 2" diameter apertures) are 24.7, 24.2, and 24.4 AB mag in the J, H, and Ks bands, respectively. We also release a multiband photometry and photometric redshift catalog containing 93598 sources. For non-X-ray sources, we obtained a photometric redshift accuracy {sigma}_NMAD_=0.036 with an outlier fraction {eta}=7.3%. For X-ray sources, which are mainly active galactic nuclei (AGNs), we cross-matched our catalog with the updated 2M-CDFN X-ray catalog from Xue+ (2016, J/ApJS/224/15) and found that 658 out of 683 X-ray sources have counterparts. GALEX UV data are included in the photometric redshift computation for the X-ray sources to give {sigma}_NMAD_=0.040 with {eta}=10.5%. Our approach yields more accurate photometric redshift estimates compared to previous works in this field. In particular, by adopting AGN-galaxy hybrid templates, our approach delivers photometric redshifts for the X-ray counterparts with fewer outliers compared to the 3D-Hubble Space Telescope catalog, which fit these sources with galaxy-only templates.
- ID:
- ivo://CDS.VizieR/J/ApJS/215/27
- Title:
- Photometric redshifts in the Hawaii-HDF-N
- Short Name:
- J/ApJS/215/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive photometric redshifts (z_phot_) for sources in the entire (~0.4deg^2^) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point-spread-function-matched photometry of 15 broad bands from the ultraviolet (U band) to mid-infrared (IRAC 4.5{mu}m). Our catalog consists of a total of 131678 sources. We evaluate the z_phot_ quality by comparing z_phot_with spectroscopic redshifts (z_spec_) when available, and find a value of normalized median absolute deviation {sigma}_NMAD_=0.029 and an outlier fraction of 5.5% (outliers are defined as sources having |z_phot_-z_spec_|/(1+z_spec_)>0.15) for non-X-ray sources. More specifically, we obtain {sigma}_NMAD_=0.024 with 2.7% outliers for sources brighter than R=23mag, {sigma}_NMAD_=0.035 with 7.4% outliers for sources fainter than R=23mag, {sigma}_NMAD_=0.026 with 3.9% outliers for sources having z<1, and {sigma}_NMAD_=0.034 with 9.0% outliers for sources having z>1. Our z_phot_ quality shows an overall improvement over an earlier z_phot_ work that focused only on the central H-HDF-N area. We also classify each object as a star or galaxy through template spectral energy distribution fitting and complementary morphological parameterization, resulting in 4959 stars and 126719 galaxies. Furthermore, we match our catalog with the 2Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having z_spec_), we improve their z_phot_ quality by adding three additional active galactic nucleus templates, achieving {sigma}_NMAD_=0.035 and an outlier fraction of 12.5%.
- ID:
- ivo://CDS.VizieR/J/ApJS/187/560
- Title:
- Photometric redshifts of the 2Ms CDF-S
- Short Name:
- J/ApJS/187/560
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present reliable multiwavelength identifications and high-quality photometric redshifts for the 462 X-ray sources in the ~2Ms Chandra Deep Field-South (CDF-S) survey (Cat. J/ApJS/179/19). Source identifications are carried out using deep optical-to-radio multiwavelength catalogs, and are then combined to create lists of primary and secondary counterparts for the X-ray sources. We identified reliable counterparts for 442 (95.7%) of the X-ray sources, with an expected false-match probability of ~6.2%; we also selected four additional likely counterparts. The majority of the other 16 X-ray sources appear to be off-nuclear sources, sources associated with galaxy groups and clusters, high-redshift active galactic nuclei (AGNs), or spurious X-ray sources. A likelihood-ratio method is used for source matching, which effectively reduces the false-match probability at faint magnitudes compared to a simple error-circle matching method. We construct a master photometric catalog for the identified X-ray sources including up to 42 bands of UV-to-infrared data, and then calculate their photometric redshifts (photo-z's). The typical photo-z accuracy is ~6%-7%.
- ID:
- ivo://CDS.VizieR/J/AJ/161/82
- Title:
- Photometric & spectroscopic obs. of TOI-954 and K2-329
- Short Name:
- J/AJ/161/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of two short-period Saturn-mass planets, one transiting the G subgiant TOI-954 (TIC44792534, V=10.343, T=9.78) observed in TESS sectors 4 and 5 and one transiting the G dwarf K2-329 (EPIC246193072, V=12.70, K=10.67) observed in K2 campaigns 12 and 19. We confirm and characterize these two planets with a variety of ground-based archival and follow-up observations, including photometry, reconnaissance spectroscopy, precise radial velocity, and high-resolution imaging. Combining all available data, we find that TOI-954b has a radius of 0.852_-0.062_^+0.053^R_Jup_ and a mass of 0.174_-0.017_^+0.018^M_Jup_ and is in a 3.68day orbit, while K2-329b has a radius of 0.774_-0.024_^+0.026^R_Jup_ and a mass of 0.260_-0.022_^+0.020^M_Jup_ and is in a 12.46day orbit. As TOI-954b is 30 times more irradiated than K2-329b but more or less the same size, these two planets provide an opportunity to test whether irradiation leads to inflation of Saturn-mass planets and contribute to future comparative studies that explore Saturn-mass planets at contrasting points in their lifetimes.
- ID:
- ivo://CDS.VizieR/J/A+A/402/1157
- Title:
- Photometric standards around gravitational lenses
- Short Name:
- J/A+A/402/1157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of secondary photometric standard stars in the neighborhood of 14 gravitationally lensed quasars. These stars were verified to be non variable using long-term monitoring. The instrumental magnitudes of the new standard stars have been transformed to the Johnson-Cousins BV(RI)c photometric system. For ten gravitational lenses (GLs) we also provide the BV(RI)c mean magnitudes of the integrated flux of all the lens components, for the epochs of the photometric calibration.
- ID:
- ivo://CDS.VizieR/J/A+A/458/225
- Title:
- Photometric standard stars in the field of GR 290
- Short Name:
- J/A+A/458/225
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Understanding the origin of the instabilities of LBVs is important for shedding light on the late evolutionary stages of massive stars and on the chemical evolution of galaxies. To investigate the physical nature of variable stars in the upper H-R diagram, we performed a spectrophotometric study of the Romano's star GR 290 and the Hubble-Sandage variables A, B, and C in the close galaxy M 33. New spectroscopic and photometric data were employed in conjunction with already published data of these stars in order to derive spectral types, energy distribution and bolometric luminosities.
