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- ID:
- ivo://CDS.VizieR/J/ApJ/779/L6
- Title:
- 3D kinematic observations of stars in Galactic Centre
- Short Name:
- J/ApJ/779/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present three-dimensional (3D) kinematic observations of stars within the central 0.5pc of the Milky Way (MW) nuclear star cluster (NSC) using adaptive optics imaging and spectroscopy from the Keck telescopes. Recent observations have shown that the cluster has a shallower surface density profile than expected for a dynamically relaxed cusp, leading to important implications for its formation and evolution. However, the true 3D profile of the cluster is unknown due to the difficulty in de-projecting the stellar number counts. Here, we use spherical Jeans modeling of individual proper motions and radial velocities to constrain, for the first time, the de-projected spatial density profile, cluster velocity anisotropy, black hole mass (M_BH_), and distance to the Galactic center (R_0_) simultaneously. We find that the inner stellar density profile of the late-type stars, {rho}(r){prop.to}r^-{gamma}^, have a power law slope {gamma}=0.05_-0.60^+0.29^, much more shallow than the frequently assumed Bahcall-Wolf slope of {gamma}=7/4. The measured slope will significantly affect dynamical predictions involving the cluster, such as the dynamical friction time scale. The cluster core must be larger than 0.5 pc, which disfavors some scenarios for its origin. Our measurement of M_BH_=5.76_-1.26_^+1.76^x10^6^M_{sun}_ and R_0_=8.92_-0.55_^+0.58^kpc is consistent with that derived from stellar orbits within 1" of Sgr A*. When combined with the orbit of S0-2, the uncertainty on R_0_ is reduced by 30% (8.46_-0.38_^+0.42^kpc). We suggest that the MW NSC can be used in the future in combination with stellar orbits to significantly improve constraints on R_0_.
1673. DK Lac V light curves
- ID:
- ivo://CDS.VizieR/J/AJ/141/122
- Title:
- DK Lac V light curves
- Short Name:
- J/AJ/141/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on extensive photometry of DK Lac obtained during the interval 1990-2009, which includes a 2mag low state during 2001-2003. Much of the photometry consists of exposures obtained with a typical spacing of several days, but also includes 26 sequences of continuous photometry each lasting 2-7hr. We find no evidence for periodicities in our data.
- ID:
- ivo://CDS.VizieR/J/A+A/349/515
- Title:
- DL Cygni ubr differential photometry
- Short Name:
- J/A+A/349/515
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Relative photometry of DL Cygni versus GSC 3595-0200 in the instrumental system
1675. DM Cyg BVIc light curves
- ID:
- ivo://CDS.VizieR/J/MNRAS/397/350
- Title:
- DM Cyg BVIc light curves
- Short Name:
- J/MNRAS/397/350
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- DM Cyg, a fundamental mode RRab star, was observed in the 2007 and 2008 seasons in the framework of the Konkoly Blazhko Survey. Very small amplitude light-curve modulation was detected with 10.57d modulation period. The maximum brightness and phase variations do not exceed 0.07mag and 7min, respectively. In spite of the very small amplitude of the modulation, beside the frequency triplets characterizing the Fourier spectrum of the light curve, two quintuplet components were also identified. The accuracy and the good phase coverage of our observations made it possible to analyse the light curves at different phases of the modulation separately.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A99
- Title:
- DoAr 44 ugri light curves
- Short Name:
- J/A+A/643/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young stars interact with their accretion disk through their strong magnetosphere. We aim to investigate the magnetospheric accretion/ejection process in the young stellar system DoAr 44 (V2062 Oph). We monitored the system over several rotational cycles, combining high-resolution spectropolarimetry at both optical and near-IR wavelengths with long-baseline near-IR inteferometry and multicolor photometry. We derive a rotational period of 2.96d from the system's light curve, which is dominated by stellar spots. We fully characterize the central star's properties from the high signal-to-noise, high-resolution optical spectra we obtained during the campaign. DoAr 44 is a young 1.2M_{sun}_ star, moderately accreting from its disk (Macc=6.510^-9^M_{sun}_/yr), and seen at a low inclination (i~=30{deg}). Several optical and near-IR line profiles probing the accretion funnel flows (H{alpha}, H{beta}, HeI 1083nm, Pa{beta}) and the accretion shock (HeI 587.6nm) are modulated at the stellar rotation period. The most variable line profile is HeI 1083nm, which exhibits modulated redshifted wings that are a signature of accretion funnel flows, as well as deep blueshifted absorptions indicative of transient outflows. The Zeeman-Doppler analysis suggests the star hosts a mainly dipolar magnetic field, inclined by about 20{deg} onto the spin axis, with an intensity reaching about 800G at the photosphere, and up to 2+/-0.8kG close to the accretion shock. The magnetic field appears strong enough to disrupt the inner disk close to the corotation radius, at a distance of about 4.6R* (0.043au), which is consistent with the 5R* (0.047au) upper limit we derived for the size of the magnetosphere in our Paper I from long baseline interferometry. DoAr 44 is a pre-transitional disk system, exhibiting a 25-30au gap in its circumstellar disk, with the inner and outer disks being misaligned. On a scale of 0.1au or less, our results indicate that the system is steadily accreting from its inner disk through its tilted dipolar magnetosphere. We conclude that in spite of a highly structured disk on the large scale, perhaps the signature of ongoing planetary formation, the magnetospheric accretion process proceeds unimpeded at the star-disk interaction level.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A157
- Title:
- Dolidze 25 Chandra/ACIS-I X-ray sources
- Short Name:
- J/A+A/650/A157
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The dispersal of protoplanetary disks sets the timescale available for planets to assemble, and thus it is one of the fundamental parameters in theories of planetary formation. Disk dispersal is determined by several properties of the central star, the disk itself, and the surrounding environment. In particular, the metallicity of disks may impact their evolution, even if to date controversial results exist: in low-metallicity clusters disks seem to rapidly disperse, while in the Magellanic Clouds some evidence supports the existence of accreting disks few tens of Myrs old. In this paper we study the dispersal timescale of disks in Dolidze 25, the young cluster in proximity of the Sun with lowest metallicity, with the aim of understanding whether disk evolution is impacted by the low-metallicity of the cluster. We have analyzed Chandra/ACIS-I observations of the cluster and combined the resulting source catalog with existing optical and infrared catalogs of the region. We selected the disk-bearing population in a 1 degree circular region centered on Dolidze~25 from criteria based on infrared colors, and the disk-less population within a smaller central region among the X-ray sources with OIR counterpart. In both cases, criteria are applied to discard contaminating sources in the foreground/background. We have derived stellar parameters from isochrones fitted to color-magnitude diagrams. We derived a disk fraction of about 34% and a median age of the cluster of 1.2Myrs. To minimize the impact of incompleteness and spatial inhomogeneity of the list of members, we restricted this calculation to stars in a magnitude range where our selection of cluster members is fairly complete and by adopting different cuts in stellar masses. By comparing this estimate with existing estimates of the disk fraction of clusters younger than 10Myrs, our study suggests that the disk fraction of Dolidze 25 is lower than what is expected from its age alone. Even if our results are not conclusive given the intrinsic uncertainty on stellar ages estimated from isochrones fitting to color-magnitude diagrams, we suggest that disk evolution in Dolidze 25 may be impacted by the environment. Given the poor O star population and low stellar density of the cluster, it is more likely that disks dispersal timescale is dictated more by the low metallicity of the cluster rather than external photoevaporation or dynamical encounters.
1678. 30 Dor
- ID:
- ivo://CDS.VizieR/J/ApJ/413/604
- Title:
- 30 Dor
- Short Name:
- J/ApJ/413/604
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/II/187A
- Title:
- 30 Doradus OB Associations
- Short Name:
- II/187A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Johnson UBV photometry is presented for 2395 stars in the OB associations of 30 Doradus in the Large Magellanic Cloud. The CCD fields cover an area of 50 square arcminutes in the central region. The entire catalog (exclusive of the dense core cluster R136) is photometrically complete to V=B=18mag and U=17mag, although the completeness magnitudes are fainter for regions with less nebular contamination.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/115
- Title:
- Double-component model fitting of elliptical gal.
- Short Name:
- J/ApJ/836/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate two-dimensional image decomposition of nearby, morphologically selected early-type galaxies (ETGs). We are motivated by recent observational evidence of significant size growth of quiescent galaxies and theoretical development advocating a two-phase formation scenario for ETGs. We find that a significant fraction of nearby ETGs show changes in isophotal shape that require multi-component models. The characteristic sizes of the inner and outer component are ~3 and ~15kpc. The inner component lies on the mass-size relation of ETGs at z~0.25-0.75, while the outer component tends to be more elliptical and hints at a stochastic buildup process. We find real physical differences between single- and double-component ETGs, with double-component galaxies being younger and more metal-rich. The fraction of double-component ETGs increases with increasing {sigma} and decreases in denser environments. We hypothesize that double-component systems were able to accrete gas and small galaxies until later times, boosting their central densities, building up their outer parts, and lowering their typical central ages. In contrast, the oldest galaxies, perhaps due to residing in richer environments, have no remaining hints of their last accretion episode.
