- ID:
- ivo://CDS.VizieR/J/MNRAS/440/3809
- Title:
- KIC 10670103 frequency spectrum
- Short Name:
- J/MNRAS/440/3809
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse 2.75yr of Kepler spacecraft observations of the pulsating subdwarf B star KIC 10670103. These 1.4 million measurements have an impressive duty cycle of 93.8 per cent, a frequency resolution of 0.017{mu}Hz, and a 5{sigma} detection limit of 0.1 parts-per-thousand (ppt). We detect 278 periodicities, making KIC 10670103 the richest pulsating subdwarf B star to date. Frequencies range from 23 to 673{mu}Hz (0.4 and 11.8h), with amplitudes from the detection limit up to 14 ppt. Follow-up spectroscopic data were obtained from which it was determined that KIC 10670103 does not show significant radial velocity variations. Updated atmospheric model fits determined T_eff_=21485+/-540K, logg=5.14+/-0.05, and logN(He)/N(H) =-2.60+/-0.04. We identify pulsation modes using asymptotic period spacings and frequency multiplets. The frequency multiplets indicate a spin period of 88+/-8d. Of the 278 periodicities detected in KIC 10670103, 163 (59 per cent) have been associated with low-degree (l<=2) pulsation modes, providing tight constraints for model fitting. While the data are exquisite, amplitudes (and some frequencies) are not stable over the course of the observations, requiring tools which are non-standard for compact pulsators such as sliding Fourier transforms and Lorentzian fitting. Using the 163 identified pulsation modes, it is possible to make detailed examinations of the pulsation structure; including where the pulsation power is concentrated in radial order, over what frequency range mode trapping is inefficient, and how power switches between multiplet members.
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1312. KIC 8462852 GTC spectra
- ID:
- ivo://CDS.VizieR/J/A+A/610/L12
- Title:
- KIC 8462852 GTC spectra
- Short Name:
- J/A+A/610/L12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report ground-based spectrophotometry of KIC 8462852, during its first dimming events since the end of the Kepler mission. The dimmings show a clear colour-signature, and are deeper in visual blue wavelengths than in red ones. The flux loss' wavelength dependency can be described with an absorption Angstroem coefficient of 2.19+/-0.45, which is compatible with absorption by optically thin dust with particle sizes on the order of 0.0015 to 0.15um. These particles would be smaller than is required to be resistant against blow-out by radiation pressure when close to the star. During occultation events, these particles must be replenished on time-scales of days. If dust is indeed the source of KIC 8462852's dimming events, deeper dimming events should show more neutral colours, as is expected from optically thick absorbers.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A94
- Title:
- KIC red giants radial modes amplitude & lifetime
- Short Name:
- J/A+A/616/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The space-borne missions CoRoT and Kepler have provided photometric observations of unprecedented quality. The study of solar-like oscillations observed in red giant stars by these satellites allows a better understanding of the different physical processes occurring in their interiors. In particular, the study of the mode excitation and damping is a promising way to improve our understanding of stellar physics that has, so far, been performed only on a limited number of targets. The recent asteroseismic characterization of the evolutionary status for a large number of red giants allows us to study the physical processes acting in the interior of red giants and how they are modified during stellar evolution. In this work, we aim to obtain information on the excitation and damping of pressure modes through the measurement of the stars' pressure mode widths and amplitudes and to analyze how they are modified with stellar evolution. The objective is to bring observational constraints on the modeling of the physical processes behind mode excitation and damping. We fit the frequency spectra of red giants with well-defined evolutionary status using Lorentzian functions to derive the pressure mode widths and amplitudes. To strengthen our conclusions, we used two different fitting techniques. Pressure mode widths and amplitudes were determined for more than 5000 red giants. With a stellar sample two orders of magnitude larger than previous results, we confirmed that the mode width depends on stellar evolution and varies with stellar effective temperature. In addition, we discovered that the mode width depends on stellar mass. We also confirmed observationally the influence of the stellar metallicity on the mode amplitudes, as predicted by models.
- ID:
- ivo://CDS.VizieR/J/A+A/598/A62
- Title:
- KIC red giants showing depressed mixed modes
- Short Name:
- J/A+A/598/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Seismic observations with the space-borne Kepler mission have shown that a number of evolved stars exhibit low-amplitude dipole modes, which is referred to as depressed modes. Recently, these low amplitudes have been attributed to the presence of a strong magnetic field in the stellar core of those stars. Subsequently, and based on this scenario, the prevalence of high magnetic fields in evolved stars has been inferred. It should be noted, however, that this conclusion remains indirect. We intend to study the properties of mode depression in evolved stars, which is a necessary condition before reaching conclusions about the physical nature of the mechanism responsible for the reduction of the dipole mode amplitudes. We perform a thorough characterization of the global seismic parameters of depressed dipole modes and show that these modes have a mixed character. The observation of stars showing dipole mixed modes that are depressed is especially useful for deriving model-independent conclusions on the dipole mode damping. We use a simple model to explain how mode visibilities are connected to the extra damping seen in depressed modes. Results. Observations prove that depressed dipole modes in red giants are not pure pressure modes but mixed modes. This result, observed in more than 90% of the bright stars (m_V_<=11), invalidates the hypothesis that depressed dipole modes result from the suppression of the oscillation in the radiative core of the stars. Observations also show that, except for visibility, seismic properties of the stars with depressed modes are equivalent to those of normal stars. The measurement of the extra damping that is responsible for the reduction of mode amplitudes, without any prior on its physical nature, potentially provides an efficient tool for elucidating the mechanism responsible for the mode depression. The mixed nature of the depressed modes in red giants and their unperturbed global seismic parameters carry strong constraints on the physical mechanism responsible for the damping of the oscillation in the core. This mechanism is able to damp the oscillation in the core but cannot fully suppress it. Moreover, it cannot modify the radiative cavity probed by the gravity component of the mixed modes. The recent mechanism involving high magnetic fields proposed for explaining depressed modes is not compliant with the observations and cannot be used to infer the strength and prevalence of high magnetic fields in red giants.
- ID:
- ivo://CDS.VizieR/J/A+A/657/A125
- Title:
- KI diagnostic capabilities for M dwarfs
- Short Name:
- J/A+A/657/A125
- Date:
- 21 Mar 2022 09:37:41
- Publisher:
- CDS
- Description:
- The strong KI doublet near 7700{AA} and another doublet near 12500{AA} are studied in a sample of 324 M dwarfs using CARMENES spectra. For the optical doublet we use only the red line, since the blue line is often contaminated by telluric correction artefacts. Both doublets have a dominant photospheric component in inactive stars and can be used as tracers of effective temperature and gravity. For M dwarfs later than M5.0V the optical doublet lines develop an emission core. The line is often correlated to H{alpha} for stars with H{alpha} in emission and anticorrelated for stars with H{alpha} in absorption. The near-infrared doublet lines very rarely show correlation/anti-correlation to H{alpha}.
- ID:
- ivo://CDS.VizieR/J/ApJ/893/4
- Title:
- KiDS ultracompact massive galaxies sp. obs.
- Short Name:
- J/ApJ/893/4
- Date:
- 03 Dec 2021 00:37:06
- Publisher:
- CDS
- Description:
- Ultracompact massive galaxies (UCMGs), i.e., galaxies with stellar masses M_*_>8x10^10^M_{sun}_ and effective radii R_e_<1.5kpc, are very rare systems, in particular at low and intermediate redshifts. Their origin as well as their number density across cosmic time are still under scrutiny, especially because of the paucity of spectroscopically confirmed samples. We have started a systematic census of UCMG candidates within the ESO Kilo Degree Survey, together with a large spectroscopic follow-up campaign to build the largest possible sample of confirmed UCMGs. This is the third paper of the series and the second based on the spectroscopic follow-up program. Here, we present photometrical and structural parameters of 33 new candidates at redshifts 0.15<~z<~0.5 and confirm 19 of them as UCMGs, based on their nominal spectroscopically inferred M_*_ and R_e_. This corresponds to a success rate of ~58% , nicely consistent with our previous findings. The addition of these 19 newly confirmed objects allows us to fully assess the systematics on the system selection-and to finally reduce the number density uncertainties. Moreover, putting together the results from our current and past observational campaigns and some literature data, we build the largest sample of ucmgs ever collected, comprising 92 spectroscopically confirmed objects at 0.1<~z<~0.5. This number raises to 116, allowing for a 3{sigma} tolerance on the M_*_ and R_e_ thresholds for the ucmg definition. For all these galaxies, we have estimated the velocity dispersion values at the effective radii, which have been used to derive a preliminary mass-velocity dispersion correlation.
- ID:
- ivo://CDS.VizieR/J/A+AS/110/19
- Title:
- Kinematical observations of pairs of galaxies
- Short Name:
- J/A+AS/110/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocities for 203 galaxies in 105 pairs and 2 triplets. The majority are close pairs of early-type galaxies; there are also pairs including a giant spiral galaxy (generally M51 type), and a few are wide pairs of early-type galaxies. Most velocities were measured from the absorption lines in the region of Mgb; emission-line velocities are also given for 22 galaxies. The velocity of one component only was measured in 13 (generally hierarchical) pairs. Velocity dispersions were measured for a subsample of 18 close pairs of early-type galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A40
- Title:
- Kinematical profiles of nearby galaxies
- Short Name:
- J/A+A/593/A40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the largest catalog of detailed stellar kinematics of the central parts of nearby galaxies, which includes higher moments of the line-of-sight velocity distribution (LOSVD) function represented by the Gauss-Hermite series. The kinematics is measured on a sample of galaxies selected from the Arecibo Legacy Fast ALFA (Alfalfa) survey using spectroscopy from the Sloan Digital Sky Survey (SDSS DR7). The SDSS DR7 offers measurements of the LOSVD based on the assumption of a pure Gaussian shape of the broadening function caused by the combination of rotational and random motion of the stars in galaxies. We discuss the consequences of this oversimplification since the velocity dispersion, one of the measured quantities, often serves as the proxy to important modeling parameters such as the black-hole mass and the virial mass of galaxies. The publicly available pPXF code is used to calculate the full kinematical profile for the sample galaxies including higher moments of their LOSVD. Both observed and synthetic stellar libraries were used and the related template mismatch problem is discussed. For the whole sample of 2180 nearby galaxies reflecting morphological distribution characteristic for the local Universe, we successfully recovered stellar kinematics of their central parts, including higher order moments of the LOSVD function, for signal-to-noise above 50.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/10
- Title:
- Kinematic analysis of M7-L8 dwarfs
- Short Name:
- J/ApJS/225/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematic analysis of 152 low surface gravity M7-L8 dwarfs by adding 18 new parallaxes (including 10 for comparative field objects), 38 new radial velocities, and 19 new proper motions. We also add low- or moderate-resolution near-infrared spectra for 43 sources confirming their low surface gravity features. Among the full sample, we find 39 objects to be high-likelihood or new bona fide members of nearby moving groups, 92 objects to be ambiguous members and 21 objects that are non-members. Using this age-calibrated sample, we investigate trends in gravity classification, photometric color, absolute magnitude, color-magnitude, luminosity, and effective temperature.
- ID:
- ivo://CDS.VizieR/J/ApJ/858/118
- Title:
- Kinematic data of 3 nearby low-mass galaxies
- Short Name:
- J/ApJ/858/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study of the nuclear star clusters (NSCs) and massive black holes (BHs) of four of the nearest low-mass early-type galaxies: M32, NGC 205, NGC 5102, and NGC 5206. We measure the dynamical masses of both the BHs and NSCs in these galaxies using Gemini/NIFS or VLT/SINFONI stellar kinematics, Hubble Space Telescope (HST) imaging, and Jeans anisotropic models. We detect massive BHs in M32, NGC 5102, and NGC 5206, while in NGC 205, we find only an upper limit. These BH mass estimates are consistent with previous measurements in M32 and NGC 205, while those in NGC 5102 and NGC 5206 are estimated for the first time and both found to be <10^6^M_{sun}_. This adds to just a handful of galaxies with dynamically measured sub-million M_{sun}_ central BHs. Combining these BH detections with our recent work on NGC 404's BH, we find that 80% (4/5) of nearby, low-mass (10^9^-10^10^M_{sun}_; {sigma}_*_~20-70km/s) early-type galaxies host BHs. Such a high occupation fraction suggests that the BH seeds formed in the early epoch of cosmic assembly likely resulted in abundant seeds, favoring a low-mass seed mechanism of the remnants, most likely from the first generation of massive stars. We find dynamical masses of the NSCs ranging from 2 to 73x10^6^M_{sun}_ and compare these masses to scaling relations for NSCs based primarily on photometric mass estimates. Color gradients suggest that younger stellar populations lie at the centers of the NSCs in three of the four galaxies (NGC 205, NGC 5102, and NGC 5206), while the morphology of two are complex and best fit with multiple morphological components (NGC 5102 and NGC 5206). The NSC kinematics show they are rotating, especially in M32 and NGC 5102 (V/{sigma}_*_~0.7).
