A5070641122- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- History and Developments in Astronomy
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Adaptive optics and wavefront sensing
- Solar and Space Plasma Dynamics
- Space Science and Extraterrestrial Life
- Neurology and Historical Studies
- Historical Astronomy and Related Studies
Heidelberg University
2016-2024
European Southern Observatory
2023-2024
Observatoire de la Côte d’Azur
2021-2023
Centre National de la Recherche Scientifique
2021-2023
Masaryk University
2016
The central kiloparsecs of the Milky Way are known to host an old, spheroidal stellar population, whose spatial and kinematical properties set it apart from boxy/peanut structure that constitutes most mass. nature this whether a small classical bulge, innermost halo or population disk stars with large initial velocity dispersion, remains unclear. This is also promising candidate some oldest in Galaxy. Here we address topic inner spheroid age, using spectroscopic photometric metallicities for...
Abstract We performed the largest and most homogeneous spectroscopic survey of field RR Lyraes (RRLs). secured ≈6300 high-resolution (HR, R ∼ 35,000) spectra for 143 RRLs (111 fundamental, RRab; 32 first-overtone, RRc). The atmospheric parameters were estimated by using traditional approach iron abundances measured an LTE line analysis. resulting distribution shows a well-defined metal-rich tail approaching solar abundance. This suggests that experienced complex chemical enrichment in early...
We present a new set of period–absolute magnitude–metallicity (PMZ) relations for single-mode RR Lyrae stars calibrated the optical G BP , V RP near-infrared I J H and K s passbands. compiled large dataset (over 100 objects) fundamental first-overtone pulsators consisting mean intensity magnitudes, reddenings, pulsation properties, iron abundances, parallaxes measured by Gaia astrometric satellite in its third data release. Our newly PMZ encapsulate most up-to-date ingredients terms both...
Abstract We provide the largest and most homogeneous sample of α -element (Mg, Ca, Ti) iron abundances for field RR Lyrae (RRLs; 162 variables) by using high-resolution spectra. The current measurements were complemented with similar available in literature 46 RRLs brought to our metallicity scale. ended up a old ( t ≥ 10 Gyr), low-mass stellar tracers (208 RRLs: 169 fundamental, 38 first overtone, 1 mixed mode) covering 3 dex abundance (−3.00 ≤ [Fe/H] 0.24). found that are ∼0.3 more poor...
Mapping the Galactic spiral structure is a difficult task since Sun located in plane and because of dust extinction. For these reasons, molecular masers radio wavelengths have been used with great success to trace Milky Way arms. Recently, Gaia parallaxes helped investigating Solar extended neighborhood. In this paper, we propose determine location arms using Cepheids they are bright, young supergiants accurate distances (they first ladder extragalactic distance scale). They can be observed...
We created new reddening maps and derived extinction laws from visual to near-infrared passbands using improved RR~Lyrae period-absolute magnitude-metallicity relations, thus enabling distance estimates for individual bulge variables. The law is most uniform in RIK RJK the distances based on these colors are determined with an accuracy six four percent, respectively. Using only estimation we inferred Galactic center equal djk = 8.2 +- 0.001(stat) 0.53(sys)pc after geometrical correction....
RR Lyrae stars toward the Galactic bulge are used to investigate whether this old stellar population traces bar. Although bar is known dominate mass in inner Galaxy, there no consensus on star population, which constitutes some of most ancient and thus earliest epochs formation, contributes barred bulge. We create new reddening maps derive extinction laws from visual near-infrared passbands using improved period-absolute magnitude-metallicity relations, enabling distance estimates for...
We present a kinematical study of 314 RR~Lyrae stars in the solar neighbourhood using publicly available photometric, spectroscopic, and {\it Gaia} DR2 astrometric data to explore their distribution Milky Way. report an overdensity 22 at pericenter distance between 5--9\,kpc from Galactic center. Their orbital parameters chemistry indicate that these variables share kinematics [Fe/H] values disc, with average metallicity tangential velocity [Fe/H]=$-0.60$\,dex $v_{\theta} =...
We discuss the largest and most homogeneous spectroscopic dataset of field RR Lyrae variables (RRLs) available to date. estimated abundances using both high-resolution low-resolution ({\Delta S} method) spectra for fundamental (RRab) first overtone (RRc) RRLs. The iron 7,941 RRLs were supplemented with similar literature estimates available, ending up 9,015 (6,150 RRab, 2,865 RRc). metallicity distribution shows a mean value <[Fe/H]> = -1.51\pm0.01, {\sigma}(standard deviation)= 0.41 dex...
ABSTRACT We have performed a critical evaluation of the membership status all variable stars in globular clusters recorded Catalogue Variable Stars Globular Clusters (CVSGC) curated by Christine Clement. To this end, we employed systematic and bulky analysis E. Vasiliev H. Baumgardt based on proper motions parallaxes given Gaia-EDR3. found numerous variables CVSGC which are fact field stars, is particularly case for located Galactic bulge. Using newly acquired list reliable cluster members...
We present the first paper of a series focused on Blazhko effect in RR Lyrae type stars pulsating fundamental mode, that are located Galactic bulge. A~comprehensive overview about incidence rate and light-curve characteristics is given. analysed 8\,282 having best quality data OGLE-IV survey, found at least $40.3$\,\% show modulation their light curves. The number we identified 3\,341, which largest sample ever studied implying most relevant statistical results currently available. Using...
We present chemodynamical links between the present-day Milky Way halo field star population and Galactic globular clusters (GCs) using a dataset that combines information from $\rm{\it Gaia}$ space mission Sloan Digital Sky Survey (SDSS-IV, DR14). Moreover, we incorporated sample of giant stars with distinct chemical signature (strong CN bandheads) resembles light-elements anomaly otherwise only seen in second generation GC stellar populations. Using three different tagging techniques,...
Abstract The Transiting Exoplanet Survey Satellite (TESS) space telescope is collecting continuous, high-precision optical photometry of stars throughout the sky, including thousands RR Lyrae stars. In this paper, we present results for an initial sample 118 nearby observed in TESS Sectors 1 and 2. We use differential image to generate light curves analyze their mode content modulation properties. combine accurate light-curve parameters from with parallax color information Gaia mission...
We report the discovery of high velocity candidates among RR~Lyrae stars found in Milky Way halo. identified 9 with Galactocentric velocities exceeding local escape based on assumed Galaxy potential. Based close examination their orbits', we ruled out ejection location disk and bulge. The spatial distribution revealed that seven pulsators overlap position Sagittarius stellar stream. Two these can be tentatively linked to dwarf spheroidal galaxy basis orbits. Focusing high-velocity tail...
We present the discovery of a new, peculiar form double-periodic pulsation in RR Lyrae stars. In four, long-period (P > 0.6 d) stars observed by Optical Gravitational Lensing Experiment, and classified as fundamental mode pulsators (RRab), we detect additional, low-amplitude variability, with period shorter than period. The ratios fall range similar to double-mode first overtone (RRd), exception one star, which ratio is significantly lower nearly exactly equals 0.7. Although are fairly...
We present a chemo-dynamical study of the Orphan stellar stream using catalog RR Lyrae pulsating variable stars for which photometric, astrometric, and spectroscopic data are available. Employing low-resolution spectra from Sloan Digital Sky Survey (SDSS), we determined line-of-sight velocities individual exposures derived systemic stars. In combination with stars’ metallicities Gaia EDR3 astrometry, investigated northern part stream. our probabilistic approach, found 20 single mode...
Abstract Patchick 99 is a candidate globular cluster located in the direction of Galactic bulge, with proper motion almost identical to field and extreme star contamination. A recent analysis suggests it low-luminosity population RR Lyrae stars. We present new spectra stars around 99, targeting specifically three associated as well other field. sample 53 giant selected from motions position on color–magnitude diagram are also observed. The have similar radial velocities distances, two...
We present a new set of tools to derive systemic velocities for single-mode RR Lyrae stars from visual and near-infrared spectra. derived scaling relations line-of-sight velocity templates using both APOGEE Gaia spectroscopic products combined with photometric G -band amplitudes. provide means estimate the subclasses, RRab RRc. Our analysis indicates that relation between amplitudes is nonlinear, break in linear occurring around ≈0.4 mag V did not observe such first-overtone pulsators. Using...
ABSTRACT We made a survey of the variable stars in 13.2 × arcmin$^{2}$ centred on field Galactic bulge cluster NGC 6558. A total 78 variables were found cluster. Many these are included catalogue globular clusters (Clement et al. 2001), OGLE or Gaia DR3 data releases. membership analysis based proper motions revealed that many do not belong to employed from aforementioned surveys and our own VI photometric system estimate periods, which along with light-curves morphology position...
We present a study of the Oosterhoff (Oo) dichotomy in Galactic bulge using 8\,141 fundamental mode RR~Lyrae stars. used public photometric data from Optical Gravitational Lensing Experiment (OGLE) and Vista Variables Vía Láctea survey (VVV). carefully selected stars without modulation association with any globular cluster located toward bulge. Subsequently, we identified separated groups I II on basis their period-amplitude distribution relation fitted to locus. Both were then compared...
We report the discovery of a new group double-periodic stars in OGLE Galactic bulge photometry. In 38 identified as fundamental-mode RR Lyrae and four classified first-overtone Lyrae, we detected an additional shorter periodicity. The periods dominant variability newly discovered are 0.28 < PD 0.41 d. Period ratios (0.68–0.72) smaller than period RRd stars. typical amplitude ratio (of to periodicity) is 20 per cent for 50 Lyrae. 10 from our sample exhibit equidistant peaks frequency...
Abstract We collected the largest spectroscopic catalog of RR Lyrae (RRLs) including ≈20,000 high-, medium-, and low-resolution spectra for ≈10,000 RRLs. provide analytical forms radial velocity curve (RVC) templates. These were built using 36 RRLs (31 fundamental—split into three period bins—and five first-overtone pulsators) with well-sampled RVCs based on groups metallic lines (Fe, Mg, Na) four Balmer (H α , H β γ δ ). tackled long-standing problem reference epoch to anchor light-curve...
ABSTRACT We present 20 newly discovered candidates for binary systems with an RR Lyrae companion. Using the photometric data from Optical Gravitational Lensing Experiment (OGLE) and Korea Microlensing Telescope Network (KMTNet) Galactic bulge, we searched among non-modulated fundamental-mode variables. constructed investigated over 9000 O − C diagrams individual pulsators, in order to find signs of light-travel time effect. found variables exhibiting cyclic variation (time observed minus...
We present a kinematical study of RR~Lyrae stars associated with two Oosterhoff groups in the Galactic bulge. used data published first paper series, plus proper motions from {\it Gaia} Data Release 2, and radial velocities literature. A 6D spatial solution was obtained for 429 stars. use model gravitational potential to infer stellar orbits. did not find difference between individual components space velocity. report that \textit{foreground} \textit{background} respect bulge stand out mean...