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5591. rho Cas differential BVRI photometry
ID:
ivo://CDS.VizieR/J/A+A/631/A48
Title:
rho Cas differential BVRI photometry
Short Name:
J/A+A/631/A48
Date:
21 Oct 2021
Publisher:
CDS
Description:
We aim to explore the variable photometric and stellar properties of four yellow hypergiants (YHGs), HR 8752, HR 5171A, rho Cas, and HD 179821, and their pulsations of hundreds of days, and long-term variations (LTVs) of years. We also aim to explore light and colour curves for characteristics betraying evolutionary loops and eruptive episodes and to investigate trends of quasi-periods and the possible need for distance revisions. We tackled multi-colour and visual photometric data sets, looked for photometric indications betraying eruptions or enhanced mass-loss episodes, calculated stellar properties mainly using a previously published temperature calibration, and investigated the nature of LTVs and their influence on quasi-periods and stellar properties. Based on driven one-zone stellar oscillation models, the pulsations can be characterised as 'weakly chaotic'. The BV photometry revealed a high-opacity layer in the atmospheres. When the temperature rises the mass loss increases as well, consequently, as the density of the high-opacity layer. As a result, the absorption in B and V grow. The absorption in B, presumably of the order of one to a few 0.1mag, is always higher than in V. This difference renders redder and variable (B-V) colour indexes, but the absorption law is unknown. This property of YHGs is unpredictable and explains why spectroscopic temperatures (reddening independent) are always higher than photometric ones, but the difference decreases with the temperature. A new (weak) eruption of rho Cas has been identified. We propose shorter distances for rho Cas and HR 5171A than the accepted ones. Therefore, a correction to decrease the blue luminescence of HR 5171A by polycyclic aromatic hydrocarbon (PAH) molecules is necessary, and HR 5171A would no longer be a member of the cluster Gum48d. HR 5171A is only subject to one source of light variation, not by two as the literature suggests. Eruptive episodes (lasting one to two years), of YHGs prefer relatively cool circumstances when a red evolutionary loop (RL) has shifted the star to the red on the HR diagram. After the eruption, a blue loop evolution (BL) is triggered lasting one to a few decades. We claim that in addition to HR 8752, also the other three YHGs have shown similar cycles over the last 70 years. This supports the suspicion that HD 179821 might be a YHG (with a possible eruptive episode between 1925 and 1960). The range in temperature of these cyclic Teff variations is 3000K-4000K. LTVs mainly consist of such BL and RL evolutions, which are responsible for a decrease and increase, respectively, of the quasi-periods. The reddening episode of HR 5171A between 1960 and 1974 was most likely due to a red loop evolution, and the reddening after the 1975 eruption was likely due to a shell ejection, taking place simultaneously with a blue loop evolution.
5592. rho Ophiuchus (Lynds 1688) cluster NICMOS imaging
ID:
ivo://CDS.VizieR/J/ApJ/566/993
Title:
rho Ophiuchus (Lynds 1688) cluster NICMOS imaging
Short Name:
J/ApJ/566/993
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of near-infrared photometry of young stars associated with the Ophiuchus molecular cloud based on observations made with the Hubble Space Telescope NICMOS3 camera at 1.1 and 1.6{mu}m. Our survey covers 0.02deg^2^ centered on the dense molecular cores in Lynds 1688. We detect 165 sources at 1.6{mu}m and 65 sources at 1.1{mu}m within our estimated completeness limits of 21.0 and 21.5mag, respectively.
5593. Rho Oph Near-IR Positions and Photometry
ID:
ivo://CDS.VizieR/J/ApJS/112/109
Title:
Rho Oph Near-IR Positions and Photometry
Short Name:
J/ApJS/112/109
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalog contains the tabulated results from a three-color (JHK) near-Infrared imaging survey of the Rho Ophiuchi star-forming cloud core. The NIR imaging observations were acquired using the SQIID instrument on the Kitt Peak 1.3m telescope from June 4-10, 1993 and April 23-28, 1994. The survey covered one square degree (2.2pc by 2.2pc). The catalog contains 4495 sources with both J2000.0 and B1950.0 coordinates for each source and its J, H, and K magnitudes and/or upper their limits. The Rho Ophiuchi clouds are of great interest for star formation studies, since they include the nearest example of a currently forming star cluster. The absolute positions in RA and Dec were determined for each individual source by using a centering algorithm in the IRAF package APPHOT to obtain center positions in pixels which were then merged into a single common positional grid. Absolute stellar coordinates were determined by comparing the authors positional database with the positions of 36 HST Guide Star Catalog stars spread out over the survey field. These were used to determine a plate scale and rotation which was used to generate the final list of source positions. The position determination technique and the photometric data reduction and calibration is discussed in detail in the source reference.
5594. rho Oph proper motions and photometry
ID:
ivo://CDS.VizieR/J/A+A/597/A90
Title:
rho Oph proper motions and photometry
Short Name:
J/A+A/597/A90
Date:
21 Oct 2021
Publisher:
CDS
Description:
We aim at performing a kinematic census of young stellar objects (YSOs) in the rho Ophiuchi F core and partially in the E core of the L1688 dark cloud. We run a proper motion program at the ESO New Technology Telescope (NTT) with the Son of ISAAC (SOFI) instrument over nine years in the near-infrared. We complemented these observations with various public image databases to enlarge the time base of observations and the field of investigation to 0.5{deg}x0.5{deg}. We derived positions and proper motions for 2213 objects. From these, 607 proper motions were derived from SOFI observations with a ~1.8mas/yr accuracy while the remaining objects were measured only from auxiliary data with a mean precision of about 3mas/yr. We performed a kinematic analysis of the most accurate proper motions derived in this work, which allowed us to separate cluster members from field stars and to derive the mean properties of the cluster. From the kinematic analysis we derived a list of 68 members and 14 candidate members, comprising 26 new objects with a high membership probability.
5595. RI and Teff of stars in NGC 2477
ID:
ivo://CDS.VizieR/J/A+AS/119/413
Title:
RI and Teff of stars in NGC 2477
Short Name:
J/A+AS/119/413
Date:
21 Oct 2021
Publisher:
CDS
Description:
Trough photometric methods we have constructed the luminosity function for the southern open cluster NGC 2477 down to M_v_=~12. We present R-I color-magnitude diagrams and near-infrared color-color diagrams, which allow us to separate statistically the cluster stars from the field ones, numerous because of the galactic latitude of the cluster. Our luminosity function (LF) reproduces some features obtained by other authors, namely, a dip at M_v_=~7, and a probable maximum at M_v_=~12. The method developed to separate cluster stars from field stars could be of interest to other astronomical problems.
5596. RI-band LC of microlensing event OGLE-2018-BLG-1269Lb
ID:
ivo://CDS.VizieR/J/AJ/160/148
Title:
RI-band LC of microlensing event OGLE-2018-BLG-1269Lb
Short Name:
J/AJ/160/148
Date:
08 Dec 2021
Publisher:
CDS
Description:
We report the discovery of a planet in the microlensing event OGLE-2018-BLG-1269 with a planet-host mass ratio q~6x10^-4^, i.e., 0.6 times smaller than the Jupiter/Sun mass ratio. Combined with the Gaia parallax and proper motion, a strong one-dimensional constraint on the microlens parallax vector allows us to significantly reduce the uncertainties of lens physical parameters. A Bayesian analysis that ignores any information about light from the host yields that the planet is a cold giant (M_2_=0.69_-0.22_^+0.44^M_J_) orbiting a Sun-like star (M_1_=1.13_-0.35_^+0.72^M_{sun}_) at a distance of D_L_=2.56_-0.62_^+0.92^kpc. The projected planet-host separation is a_{perp}_=4.61_-1.17_^+1.70^au. Using Gaia astrometry, we show that the blended light lies <~12mas from the host and therefore must be either the host star or a stellar companion to the host. An isochrone analysis favors the former possibility at >99.6%. The host is therefore a subgiant. For host metallicities in the range of 0.0<=[Fe/H]<=+0.3, the host and planet masses are then in the range of 1.16<=M_1_/M_{sun}_<=1.38 and 0.74<=M_2_/M_J_<=0.89, respectively. Low host metallicities are excluded. The brightness and proximity of the lens make the event a strong candidate for spectroscopic follow-up both to test the microlensing solution and to further characterize the system.
5597. R I CN TiO photometry of DDO190 carbon stars
ID:
ivo://CDS.VizieR/J/A+A/447/473
Title:
R I CN TiO photometry of DDO190 carbon stars
Short Name:
J/A+A/447/473
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have carried out deep R, I, CN, TiO observations of the dwarf irregular galaxy DDO 190. We confirm the existence intermediate-age population around this galaxy. The identification of 47 carbon stars seen up to 5 arcmin from the centre of the galaxy implies that the population distribution of DDO 190 is similar to those found in some other Local Group dIrr galaxies. An estimate of the metallicity, [Fe/H]=-1.55+/-0.12, is obtained based on the observed C/M ratio. From the analysis of star counts, corrected for the radial variation of the incompleteness level, we determine a scale-length {alpha}=40+/-5", in agreement with the recent literature.
5598. (RI)c photometry of variables in M31
ID:
ivo://CDS.VizieR/J/A+A/402/113
Title:
(RI)c photometry of variables in M31
Short Name:
J/A+A/402/113
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Cousins R and I band photometry of variable stars in a ~13'x13' region in the disk of M31 galaxy, obtained during 141 nights. Of the 26 Cepheid variables present in the region, two are newly discovered, 11 are classified as Cepheids for the first time and 13 are confirmed as Cepheids. The extensive photometry of these Cepheids enabled us to determine precise phase and amplitude of pulsation which ranges from 0.11 to 0.48mag in R band. The period of variability ranges from ~7.5 to 56 days. The period-luminosity diagram is used to derive a distance modulus of 24.49+/-0.11mag for M31 galaxy. We also report variability in 333 other stars, of them, 115 stars appear to be long period variables, 2 suspected eclipsing binaries and remaining 216 are irregular variables.
5599. Ridgelines of six intermediate-age SMC clusters
ID:
ivo://CDS.VizieR/J/AJ/136/1703
Title:
Ridgelines of six intermediate-age SMC clusters
Short Name:
J/AJ/136/1703
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a photometric analysis of the star clusters Lindsay 1, Kron 3, NGC 339, NGC 416, Lindsay 38, and NGC 419 in the Small Magellanic Cloud (SMC), observed with the Hubble Space Telescope Advanced Camera for Surveys (ACS) in the F555W and F814W filters. Our color-magnitude diagrams (CMDs) extend ~3.5mag deeper than the main-sequence turnoff points, deeper than any previous data. Cluster ages were derived using three different isochrone models: Padova, Teramo, and Dartmouth, which are all available in the ACS photometric system. Fitting observed ridgelines for each cluster, we provide a homogeneous and unique set of low-metallicity, single-age fiducial isochrones.
5600. RI differential photometry of CU Cnc
ID:
ivo://CDS.VizieR/J/A+A/398/239
Title:
RI differential photometry of CU Cnc
Short Name:
J/A+A/398/239
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photometric observations in the R and I bands of the detached M-type double-lined eclipsing binary CU Cnc have been acquired and analysed. The photometric elements obtained from the analysis of the light curves have been combined with an existing spectroscopic solution to yield high-precision (errors<2%) absolute dimensions: M_A_=0.4333+/-0.0017M_{sun}_, M_B_=0.3980+/-0.0014M_{sun}_, R_A_=0.4317+/-0.0052R_{sun}_, and R_B_=0.3908+/-0.0094R_{sun}_. The mean effective temperature of the system has been estimated to be Teff=3140+/-150K by comparing multi-band photometry with synthetic colors computed from model atmospheres. Additionally, we have been able to obtain an estimate for the age (~320Myr) and chemical composition ([Fe/H]~0.0) of the binary system through its membership of the Castor moving group.