Long-period Variables Research Articles

Long-period radial velocity variations of nine M red giants

Context. Certain periodic variations of radial velocities (RVs) of wobbling giants originate from exoplanets. A number of exoplanets have been discovered around giant stars. Aims. The purpose of our study is to find low-amplitude and long-period RV variations around bright M (super) giants in the red giant branch (or asymptotic giant branch) stage, which are long-period variables (LPVs) or high proper motion stars. Methods. The high-resolution fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at the Bohyunsan Optical Astronomy Observatory (BOAO) was used to record numerous spectra of nine giants. The observation period for the targets spanned 16 yr, from 2005 to 2022. Results. We found two substellar companions from the precise RV observations of nine M giants. One companion has a 28.26−2.17+2.05 MJ orbiting period of 663.87−4.31+4.61 days at a distance of 2.03−0.01+0.01 AU (HD 6860), and the other has a 15.83−2.74+2.33 MJ orbiting period of 466.63−1.28+1.47 days at a distance of 1.33−0.11+0.08 AU (HD 112300). Our estimate of the stellar parameters for HD 6860 makes it the currently largest star with a substellar companion. We also found RV variations mimicking a planetary companion in HD 18884 and confirmed LPVs in two stars, HD 39801 and HD 42995. The RV variations of some stars seem to be associated with stellar activities rather than reflex orbital motion due to their companions. Variations like this are also detected for HD 6860 and HD 112300, which host substellar companions.

Gaia Data Release 3

Context. The third Gaia Data Release covers 34 months of data and includes the second Gaia catalogue of long-period variables (LPVs), with G variability amplitudes larger than 0.1 mag (5–95% quantile range). Aims. The paper describes the production and content of the second Gaia catalogue of LPVs and the methods we used to compute the published variability parameters and identify C-star candidates. Methods. We applied various filtering criteria to minimise contamination from variable star types other than LPVs. The period and amplitude of the detected variability were derived from model fits to the G-band light curve wherever possible. C stars were identified using their molecular signature in the low-resolution RP spectra. Results. The catalogue contains 1 720 558 LPV candidates, including 392 240 stars with published periods (ranging from 35 to ∼1000 days) and 546 468 stars classified as C-star candidates. Comparison with literature data (OGLE and ASAS-SN) leads to an estimated completeness of 80%. The recovery rate is about 90% for the most regular stars (typically miras) and 60% for SRVs and irregular stars. At the same time, the number of known LPVs is increased by a factor of 6 with respect to literature data for amplitudes larger than 0.1 mag in G, and the contamination is estimated to be below 2%. Our C-star classification, based on solid theoretical arguments, is consistent with spectroscopically identified C stars in the literature. Caution must be taken in crowded regions, however, where the signal-ro-noise ratio of the RP spectra can become very low, or if the source is reddened by some kind of extinction. The quality and potential of the catalogue are illustrated by presenting and discussing LPVs in the solar neighbourhood, in globular clusters, and in galaxies of the Local Group. Conclusions. This is the largest all-sky LPVs catalogue to date. The photometric depth reaches G = 20 mag. This is a unique dataset for research into the late stages of stellar evolution.

GaiaData Release 3

Context.TheGaiaDR3 catalogue contains, for the first time, about 800 000 solutions with either orbital elements or trend parameters for astrometric, spectroscopic, and eclipsing binaries, and combinations of these three.Aims.With this paper, we aim to illustrate the huge potential of this large non-single-star catalogue.Methods.Using the orbital solutions and models of the binaries, we have built a catalogue of tens of thousands of stellar masses or lower limits thereof, some with consistent flux ratios. Properties concerning the completeness of the binary catalogues are discussed, statistical features of the orbital elements are explained, and a comparison with other catalogues is performed.Results.Illustrative applications are proposed for binaries across the Hertzsprung-Russell Diagram (HRD). Binarity is studied in the giant branch and a search for genuine spectroscopic binaries among long-period variables is performed. The discovery of new EL CVn systems illustrates the potential of combining variability and binarity catalogues. Potential compact object companions are presented, mainly white dwarf companions or double degenerates, but one candidate neutron star is also found. Towards the bottom of the main sequence, the orbits of previously suspected binary ultracool dwarfs are determined and new candidate binaries are discovered. The long awaited contribution ofGaiato the analysis of the substellar regime shows the brown dwarf desert around solar-type stars using true rather than minimum masses, and provides new important constraints on the occurrence rates of substellar companions to M dwarfs. Several dozen new exoplanets are proposed, including two with validated orbital solutions and one super-Jupiter orbiting a white dwarf, all being candidates requiring confirmation. Besides binarity, higher order multiple systems are also found.Conclusions.By increasing the number of known binary orbits by more than one order of magnitude,GaiaDR3 will provide a rich reservoir of dynamical masses and an important contribution to the analysis of stellar multiplicity.

Validation and Evaluation of GRACE-FO Estimates with In Situ Bottom Pressure Array Measurements in the South China Sea

The Gravity Recovery and Climate Experiment (GRACE), and its follow-on mission (GRACE-FO), provides a novel measurement of the variations in ocean bottom pressure (OBP) at global and basin scales, including those in marginal seas. However, these measurements have not yet been validated rigorously for the South China Sea (SCS). In this study, the accuracy in the monthly GRACE-FO mascon solutions in the SCS from the Jet Propulsion Laboratory (JPL), Center for Space Research (CSR), and Goddard Space Flight Center (GSFC) was validated with the results of the comparison with the in situ OBP records from an array of 25 pressure-recording inverted echo sounders (PIESs) that are located west of the Luzon Strait (LS). The correlation coefficient (Cor) and root mean square difference (RMSD) between the 10-month period of GSFC and PIES, spanning from July 2018 to June 2019 (with missing satellite data for August and September 2018), were 0.77 (p-value = 0.005) and 0.41 mbar (1 mbar = 100 Pa), respectively. These values suggest that the accuracy of GSFC in the SCS in this period was substantially better than that of JPL (Cor = 0.35, p-value = 0.16; RMSD = 0.74 mbar) and CSR (Cor = 0.25, p-value = 0.24; RMSD = 0.89 mbar). Moreover, the volume transport anomaly of the SCS abyssal circulation was estimated and compared based on the OBP records from GSFC and PIES observations, indicating that the GRACE-FO OBP (GSFC) can be used to monitor seasonal or longer-period variations in the SCS abyssal volume transport. Additionally, the variations in OBP from GRACE-FO were significantly overestimated on the continental shelf of the SCS, which may be attributed to signal leakage. Our findings provide reliable evidence for the application of long-term, fully covered OBP records from GRACE-FO in the SCS, and also offer a valuable reference for the application of GRACE-FO in other regions.

The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. VI. The Star Formation History and Dust Production in Andromeda IX

We present a photometric study of the resolved stellar populations in Andromeda IX (And IX), the closest satellite to M31, a metal-poor and low-mass dwarf spheroidal galaxy. We estimate a distance modulus of mag based on the tip of the red giant branch. By probing the variability of asymptotic giant branch stars, we study the star formation history of And IX. We identified 50 long-period variables (LPVs) in And IX using the Isaac Newton Telescope in two filters, the Sloan and Harris V. In this study, we selected LPVs within two half-light radii with amplitudes in the range of 0.2–2.20 mag. It is found that the peak of star formation reaches ∼8.2 ± 3.1 × 10−4 M ⊙ yr−1 at ≈6 Gyr ago. Our findings suggest an outside-in galaxy formation scenario for And IX with a quenching occurring Gyr ago with a star formation rate (SFR) in the order of 2.0 × 10−4 M ⊙ yr−1 at redshift <0.5. We calculate the total stellar mass by integrating the SFR within two half-light radii ∼3.0 × 105 M ⊙. By employing spectral energy distribution fitting for the observed LPVs in And IX, we evaluate a mass-loss rate in the range of 10−7 ≤ ≤ 10−5 M ⊙ yr−1. Finally, we show that the total mass deposition to the interstellar medium (ISM) is ∼2.4 × 10−4 M ⊙ yr−1 from the C- and O-rich types of dust-enshrouded LPVs. The ratio of the total mass returned to the ISM by LPVs to the total stellar mass is ∼8.0 × 10−10 yr−1, and so at this rate it would take ∼1 Gyr to reproduce this galaxy.

Meandering periods and asymmetries in light curves of Miras: Observational evidence for low mass-loss rates

Context. Some Miras (long-period variables in late evolutionary stages) have meandering pulsation periods and light-curve asymmetries, the causes of which are still unclear. Aims. We aim to better understand the origin of meandering periods and light-curve asymmetries by investigating a sample of Miras in the solar neighbourhood. We characterised this group of stars and related their variability characteristics to other stellar parameters. Methods. We analysed observations from several databases to obtain light curves with maximum time span and temporal coverage for a sample of 548 Miras. We determined their pulsation-period evolution over a time span of many decades, searched for changes in the periods, and determined the amplitude of the period change. We also analysed the Fourier spectra with respect to possible secondary frequency maxima. The sample was divided into two groups with respect to the presence of light-curve asymmetries (‘bumps’). Infrared colours and indicators of the third dredge-up were collected to study the mass loss and deep mixing properties of the stars of our sample. Results. Our analysis reveals one new star, T Lyn, with a continuously changing period. The group of Miras with meandering period changes is exclusively made up of M-type stars. The Fourier spectra of the meandering-period Miras have no prominent additional peaks, suggesting that additional pulsation modes are not the cause of the meandering periods. We confirm that light-curve bumps are more common among S and C Miras and show, for the first time, that Miras with such bumps have lower mass-loss rates than those with regular, symmetric light curves. Also, Miras with meandering period changes have relatively little mass loss. Conclusions. We conclude that Miras with strongly changing periods (including meandering periods) or asymmetries in their light curves have relatively low dust mass-loss rates. Meandering period changes and light-curve asymmetries could be connected to He-shell flashes and third dredge-up episodes.

Light-curve Recovery with the Vera Rubin Observatory’s LSST. I. Pulsating Stars in Local Group Dwarf Galaxies

This investigation is mainly focused on the LSST Survey Strategy Optimization process, a bottom-up approach that turned out to be quite effective in involving the scientific community in the definition of the LSST observing strategy. We are mainly interested in using radial variables (RR Lyrae, classical Cepheids, long-period variables) as stellar tracers and distance indicators, and we developed a new tool called PulsationStarRecovery to quantify the recovery of the light-curve period and amplitude from an LSST-simulated time series. The outputs of this code are pulsation parameters (period, amplitude, mean magnitude) together with quantitative information concerning the difference between the shape of the light curve and template light curves. Furthermore, we apply the newborn metric to simulate LSST observations and recovery of different types of pulsating stars hosted by selected massive stellar systems (19 Local Group dwarf galaxies and the Large Magellanic Cloud) to show how the recovery changes according to distance and variable-star type. We show that this exercise is essential to understand the potential of LSST in this field since excellent recovery is necessary to optimize the use of predicted period–luminosity, period–amplitude, and color–color relations to constrain the cosmic distance scale and the metallicity distribution function of different stellar populations.

Hunting for C-rich long-period variable stars in the Milky Way’s bar-bulge using unsupervised classification ofGaiaBP/RP spectra

ABSTRACTThe separation of oxygen- and carbon-rich asymptotic giant branch sources is crucial for their accurate use as local and cosmological distance and age/metallicity indicators. We investigate the use of unsupervised learning algorithms for classifying the chemistry of long-period variables from Gaia DR3’s BP/RP spectra. Even in the presence of significant interstellar dust, the spectra separate into two groups attributable to O-rich and C-rich sources. Given these classifications, we utilize a supervised approach to separate O-rich and C-rich sources without blue and red photometers (BP/RP) spectra but instead given broadband optical and infrared photometry finding a purity of our C-rich classifications of around 95 per cent. We test and validate the classifications against other advocated colour–colour separations based on photometry. Furthermore, we demonstrate the potential of BP/RP spectra for finding S-type stars or those possibly symbiotic sources with strong emission lines. Although our classification suggests the Galactic bar-bulge is host to very few C-rich long-period variable stars, we do find a small fraction of C-rich stars with periods $\gt 250\, \mathrm{day}$ that are spatially and kinematically consistent with bar-bulge membership. We argue the combination of the observed number, the spatial alignment, the kinematics, and the period distribution disfavour young metal-poor star formation scenarios either in situ or in an accreted host, and instead, these stars are highly likely to be the result of binary evolution and the evolved versions of blue straggler stars already observed in the bar-bulge.

Detecting Long-period Variability in the SDSS Stripe 82 Standards Catalog

We report the results of a search for long-period (100 < P < 600 days) periodic variability in the SDSS Stripe 82 standards catalog. The SDSS coverage of Stripe 82 enables such a search because there are on average 20 observations per band in ugriz bands for about one million sources, collected over about 6 yr, with a faint limit of r ∼ 22 mag and precisely calibrated 1%–2% photometry. We calculated the periods of variable source candidates in this sample using the Lomb–Scargle periodogram and considered the three highest periodogram peaks in each of the gri filters as relevant. Only those sources with gri periods consistent within 0.1% were later studied. We use the Kuiper statistic to ensure uniform distribution of data points in phased light curves. We present five sources with the spectra consistent with quasar spectra and plausible periodic variability. This SDSS-based search bodes well for future sensitive large-area surveys, such as the Rubin Observatory Legacy Survey of Space and Time, which, due to its larger sky coverage (about a factor of 60) and improved sensitivity (∼2 mag), will be more powerful for finding such sources.

The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. V. The Star Formation History of Sagittarius Dwarf Irregular Galaxy Derived from Long-period Variable Stars

We conducted an optical monitoring survey of the Sagittarius dwarf irregular galaxy (SagDIG) during the period of 2016 June–2017 October, using the 2.5 m Isaac Newton Telescopeat La Palama. Our goal was to identify long-period variable stars (LPVs), namely, asymptotic giant branch stars (AGBs) and red supergiant stars, to obtain the star formation history of isolated, metal-poor SagDIG. For our purpose, we used a method that relies on evaluating the relation between luminosity and the birth mass of these most evolved stars. We found 27 LPV candidates within 2 half-light radii of SagDIG. 10 LPV candidates were in common with previous studies, including one extreme-AGB (x-AGB). By adopting the metallicity Z = 0.0002 for older populations and Z = 0.0004 for younger ages, we estimated that the star formation rate changes from 0.0005 ± 0.0002 M ⊙ yr−1 kpc−2 (13 Gyr ago) to 0.0021 ± 0.0010 M ⊙ yr−1 kpc−2 (0.06 Gyr ago). Like many dwarf irregular galaxies, SagDIG has had continuous star formation activity across its lifetime, though with different rates, and experiences an enhancement of star formation since z ≃ 1. We also evaluated the total stellar mass within 2 half-light radii of SagDIG for three choices of metallicities. For metallicity Z = 0.0002 and 0.0004, we estimated the stellar mass M* = (5.4 ± 2.3) × 106 and (3.0 ± 1.3) × 106 M ⊙, respectively. Additionally, we determined a distance modulus of μ = 25.27 ± 0.05 mag, using the tip of the red giant branch.

ON THE STRESS WAVE IN THE EARTH'S BODY DUE TO DIFFERENTIAL ROTATION OF THE MANTLE AND CORE

Seismic energy generated as a result of elastic deformation of tectonic plates or blocks of rocks is realized by unloading at deformations exceeding the ultimate strength of rocks. The currently generally accepted earthquake source models are essentially local and are not able to establish a connection between seismic activity and some geophysical phenomena on a planetary scale. One of the features of seismicity is the recurrence of strong earthquakes in one place after a certain time interval. The purpose of this work is to study the influence of differential rotation of the solid core and mantle on seismic processes. It has now been established that the rate of rotation of the solid core exceeds the rate of rotation of the mantle. In relative motion, the solid core makes one revolution presumably in 200–400 years. Earlier, based on this, an explanation was proposed for long-period variations in the length of the day. In this paper, on a simple mechanical model, it is shown that the differential rotation of the elastic mantle and the solid core of an ellipsoidal shape generates a stress wave in the Earth's body. The idea of a stress wave is qualitatively new in the physical description of a seismic process. To demonstrate this effect, a solution is given to the problem of deformation of an elastic spherical shell interacting with a dumbbell-shaped solid body rotating in its cavity. When solving the problem, the apparatus of spherical vectors was used. The stress distribution of the spherical layer inside the shell is constructed and the areas of greatest risk are identified. It is shown that taking into account the differential rotation leads to the migration of the zones of greatest risk with a period equal to half the period of a complete rotation of the dumbbell relative to the shell (100–200 years). The results of the work can be useful in studying the relationship between seismicity and planetary rotation regimes.

FROM SPECTROSCOPY TO THE CHEMICAL EVOLUTION OF THE GALAXY. PART 1.

A brief review of the results obtained at Odesa Astronomical Observatory based on the stellar spectra analyses from 1892 to 2000 is presented. The review begins with the first observations of emission lines in solar prominences carried out in 1892 under the direction of Alexander Kononowitsch and includes an overview of spectrophotometric studies performed at the observatory using instruments and telescopes designed in- house; theoretical consideration of the issues of modelling physical conditions in stars and spectra simulation. It also describes the main results of the research of stars of various types, including cool giants K-, M spectral types, stars with various peculiarities of chemical composition, having enhanced lines of metals and CN bands, eclipsing binaries and binaries of different types, semi-regular and long-period variable stars, RR Lyraes, δ Scuti and λ Boötes stars, the diversity of Cepheids, blue stragglers in field and cluster populations, hot B Main-Sequence stars, etc., and finally, the enrichment with neutron-capture elements in the galactic stars.

Long-Period Variables as distance and age indicators in the era of Gaia and LSST

AbstractLong-period variables are bright, evolved red giant stars showing periodic photometric changes due to stellar pulsation. They follow one or more period-luminosity and period-age relations, which make them highly promising distance indicators and tracers of young and intermediate-age stellar populations. Such a potential is especially interesting in view of the massive amount of data delivered by modern large-scale variability surveys. Crucially, these applications require a clear theoretical understanding of pulsation physics in connection with stellar evolution. Here, I describe an ongoing effort from our collaboration dedicated to the modelling of stellar pulsation in evolved stars, and how this work is impacting our capability of investigating long-period variables and exploiting them for other astrophysical studies. Furthermore, I present our ongoing work aimed at assessing the potential of semi-regular variables, an often neglected sub-type of long-period variables, to be distance indicators complementary to their better-known, more evolved counterparts, the Mira variables.

The structure of the Milky Way from period-luminosity relations.

Disentangling the structural components of the Milky Way requires knowledge of distances to various classes of objects, both young, which trace the Galactic disk, and old, which trace the Galactic bulge and halo. Variable stars that obey period-luminosity relations are perfect distance indicators for such studies. Here we discuss recent findings on the structure of our galaxy, inferred from period-luminosity relations for both young, old and intermediate-age variable stars, including Cepheids, RR Lyrae stars, δ Scuti stars, and long-period variables.

Solar-Induced Long-Period Variations in the Vertical Component of an Electric Field in Lake Baikal

Solar-Induced Long-Period Variations in the Vertical Component of an Electric Field in Lake Baikal

Multi-decadal oscillations of surface temperatures and the impact on temperature increases

The last IPCC assessment report indicated that natural climate variability could temporarily amplify or obscure anthropogenic climate change on decadal time scales. Here we analyse global mean surface temperatures in terms of such long-period variations. We find two main oscillations, a strong oscillation with a period of about 70 years and an amplitude of about 0.09 K and a quasi-bidecadal oscillation with an amplitude of about 0.06 K. The strong oscillation shows large hemispheric differences. In the Northern hemisphere the period is longer and the amplitude is larger (about 82 years and 0.18 K) compared to the Southern hemisphere (about 47 years and 0.065 K). No obvious hemispheric differences are observed for the quasi-bidecadal oscillation. Such long-period oscillations can strengthen or weaken the temperature increase if the oscillation positively or negatively adds to the underlying long-term trend.

RRab variables with identical light-curve shapes at different pulsation periods

ABSTRACT In this paper, we report on the detection of RRab stars with quasi-identical-shape light curves but period differences as large as 0.05–0.21 d using the Galactic bulge data of the OGLE-IV survey. We have examined stars with shorter periods than the Oosterhoff I ridge of the bulge. These stars generally have smaller amplitudes and larger Fourier phase-differences than the typical bulge RRab stars have at the same period. Many of these ‘anomalous’ stars have good-quality light curves without any sign of the Blazhko modulation. Examining their Fourier parameters revealed that several of these stars show very similar light curve to the typical bulge RR Lyrae. We found hundreds of quasi-identical-shape light-curve pairs with different periods between the ‘anomalous’- and the ‘normal’-position RRab stars based on the OGLE I-band data. The OGLE V-band, and the archive VVV and MACHO surveys Ks-, b- and r-band data of these stars were also checked for light-curve-shape similarity. Finally, 149 pairs with identical-shape light curves in each available photometric band were identified. Calculating the physical properties of the variables using empirical formulae, on average, −0.5 dex, −0.13 mag, 0.67, and 165 K differences between the [Fe/H], MV, R/R⊙, and Teff values of the members of the pairs are derived, being the short-period stars less metal-poor, fainter, smaller, and hotter than the long-period variables. To explain the existence of variables with different physical properties and pulsation periods but with identical-shape light curves is a challenging task for modelling.

Variability of Equatorial Ionospheric Bubbles over Planetary Scale: Assessment of Terrestrial Drivers

Nighttime F-region field-aligned irregularities (FAIs) associated with equatorial plasma bubbles (EPBs) are impacted by terrestrial factors, such as solar irradiance and geomagnetic activity. This paper examines the impact of the planetary-scale periodic variability of terrestrial processes on EPB activity. Continual observations of the Equatorial Atmosphere Radar (EAR) have been utilized to derive the intra-seasonal variability of nighttime F-region FAIs in the context of the terrestrial factors mentioned above. A periodicity analysis using wavelet and Lomb–Scargle (LS) spectral analysis indicated significant amplitudes of the long-period planetary-scale variability in the F-region FAI signal-to-noise ratio (SNR), 10.7 cm flux, and geomagnetic indices, as well as a shorter period of variability. Interestingly, a careful inspection of the time series indicated the planetary-scale variability of F-region FAIs to be reasonably out of phase with the periodic geomagnetic variability. EPB occurrence and the FAI signal-to-noise ratio presented a systematic decrease with an increase in the level of geomagnetic activity. Non-transient quiet-time geomagnetic activity has been found to suppress both the occurrence as well as the strength of F-region FAIs. The impacts of planetary-scale geomagnetic activity appear to be non-identical in the summer and equinoctial EPBs. The results highlight the importance of periodic terrestrial processes in driving the planetary-scale variability of EPBs.

Toward Understanding the B[e] Phenomenon. IX. Nature and Binarity of MWC645

We present the results of optical and near-IR spectroscopy and multicolor photometry of the emission-line star MWC 645, which exhibits the B[e] phenomenon. The presence of positionally variable absorption lines of a cool star detected for the first time indicates that the object is a binary system. Using a combination of the photometric and spectroscopic data as well as the Gaia EDR3 distance (D = 6.5 ± 0.9 kpc), we disentangled the components’ contributions and estimated their surface temperatures and luminosities (18, 000 ± 2000 K and 4250 ± 250 K, log L/L ⊙ = 4.0 ± 0.5 and 3.1 ± 0.3 for the hot and cool components, respectively). Quasi-cyclic short-period (months) and long-period (∼4 yr) photometric variations were detected in both optical and near-IR regions, and are most likely due to variable circumstellar extinction. Our analysis suggests that MWC 645 is a member of the FS CMa group. The object’s properties can be described by an evolutionary model of a close binary system that currently undergoes a nonconservative mass transfer between intermediate-mass stars (e.g., 7 M ⊙ + 2.8 M ⊙).

Simulating the Legacy Survey of Space and Time Stellar Content with TRILEGAL

We describe a large simulation of the stars to be observed by the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). The simulation is based on the TRILEGAL code, which resorts to large databases of stellar evolutionary tracks, synthetic spectra, and pulsation models, added to simple prescriptions for the stellar density and star formation histories of the main structures of the Galaxy, to generate mock stellar samples through a population synthesis approach. The main bodies of the Magellanic Clouds are also included. A complete simulation is provided for single stars, down to the r = 27.5 mag depth of the coadded Wide–Fast–Deep survey images. A second simulation is provided for a fraction of the binaries, including the interacting ones, as derived with the BinaPSE module of TRILEGAL. We illustrate the main properties and numbers derived from these simulations, including: comparisons with real star counts; the expected numbers of Cepheids, long-period variables, and eclipsing binaries; the crowding limits as a function of seeing and filter; the star-to-galaxy ratios. Complete catalogs are accessible through the NOIRLab Astro Data Lab, while the stellar density maps are incorporated in the LSST metrics analysis framework.