arXiv subjects

R. E. Mennickent

Publications and source records attributed to R. E. Mennickent.

At least 19 recordsLinked to original sources

arXiv2026

Cyclic light variations and accretion disk evolution in the LMC eclipsing binary OGLE-LMC-DPV-062

Many intermediate-mass close binaries exhibit photometric cycles longer than their orbital periods, likely related to accretion-disk variability. Previous studies indicate that historical light curves (LC) provide key constraints on disk evolution and may help trace mass-transfer changes in these systems. We investigate the short- and long-term variability of the eclipsing system OGLE-LMC-DPV-062, with special emphasis on the long cycle. Our aims are to clarify the role of the accretion disk in these modulations, particularly on timescales of hundreds of days, and to determine the evolutionary state of the system in order to better understand its stellar components. We analyzed 32.3 years of photometric time series from OGLE in the I and V bands, and from MACHO in the BM and RM bands. Using data from multiple epochs, we modeled the accretion disk at 20 equally spaced phases of the long cycle. To solve the inverse problem, we applied an optimized simplex algorithm to derive the best-fitting parameters of the stars, orbit, and disk. The MESA code was used to assess the evolutionary stage of the system and predict its past and future evolution. We find an orbital period of 6.904858(15) d and a long cycle of 229.7 d. The orbital solutions reproduce the LC, but the quasi-conservative mass-transfer scenario yields rates too high to be compatible with the observed orbital-period stability. We find consistency with the observed orbital-to-long-period ratio under the magnetic dynamo hypothesis. The normalized mass-transfer rate follows the long cycle, reaching a maximum at minimum brightness. At that phase, the inner disk edge thickens, obscuring a larger fraction of the gainer star. Disk variability occurs mainly in its vertical extent, with a standard deviation of 69% of the mean value at the inner border, whereas changes in outer radius and temperature are smaller, 7% and 5%, respectively.

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arXiv2025

Photometric study of hot Algol-type binaries with long cycles

Double periodic variables (DPVs) are hot Algol-type interacting binary systems with an orbital and a long photometric cycle. The origin of the latter may be related to cyclic structural changes in the accretion disc that surrounds the gainer star that are driven by a variable mass-transfer rate. If this is the case, changes in the orbital light curve would be expected throughout the long cycle. We conducted a detailed photometric analysis of the light curves of 134 Large Magellanic Cloud (LMC) DPVs to investigate variations in the morphology of the orbital light curves as a function of the long-cycle phase. We separated the two photometric cycles from the Optical Gravitational Lensing Experiment (OGLE) I band light curves for the systems. We thus compared the orbital light curves at opposite long-cycle phases, investigated the stability of the long period, and analysed the residuals of the separation process to search for significant frequencies above a 1% false-alarm probability threshold. We confirm that the DPVs OGLE-LMC-DPV-097 and OGLE-BLG-ECL-157529 change most strongly in their orbital light curves throughout the long cycle. By comparison, about 50% of the sample exhibits moderate morphological variations, in particular, around orbital phase 0.5. This is likely associated with structural changes in the accretion discs. In addition, we identified 18 DPVs with variable long periods, including 10 new cases. In some of them, the long period either increases or decreases continuously over time. For the first time, we found DPV systems that alternate between the two behaviours at different epochs. Moreover, we detected frequencies in the residuals that might be directly related to changes in the morphology of the orbital curves. Finally, some previously reported frequencies disappear when a variable long period is taken into account.

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arXiv2025

The vanishing of the long photometric cycle in AU Monocerotis

Double periodic variables (DPVs) are a group of semi-detached interacting binaries that exhibit a long photometric cycle with an average length of $\sim33$ times the orbital period of the system. It has been proposed that this long photometric cycle originates from a modulated mass transfer rate from the donor star, which itself is driven by an internal magnetic dynamo. One of the most well-studied DPVs in the Milky Way is AU Monocerotis (AU Mon). We aim to enhance our understanding of the long photometric cycle in AU Mon by characterising its behaviour through the analysis of available photometric data from several databases and surveys. We summarise previous findings on the system and analyse its published multi-wavelength photometry from different sources, covering 46.3 years, to study the variability of its light curve. We find that the orbital period has remained constant over recent decades, but the long cycle of approximately 417 days vanished around 2010. From an O-C analysis, we conclude that the system is experiencing a change in its orbital period of no greater than $0.038\pm0.040$ s yr$^{-1}$, and thus, imposing a value of $2\times10^{-8}$ M$_\odot$ yr$^{-1}$ for $\dot{M}$ in a fully conservative mass transfer regime. A time-series analysis of the disentangling light curve in the Ic filter shows a transient periodicity of approximately 1910 days lasting at least 2000 days before it also disappears around the year 2020. An analysis of the available APASS light curves around the year 2013 shows a strong periodicity at approximately 280 days, which appears to be stronger in the Z filter. We report what is the second observation of the sudden disappearance of the long cycle in a DPV, after the Galactic DPV TYC 5353-1137-1. The disappearance of the long cycle in AU Mon is a strong constraint for current models that aim to explain the long cycle in DPVs.

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arXiv2024

Examining the brightness variability, accretion disk, and evolutionary stage of the binary OGLE-LMC-ECL-14413

Our study aims to elucidate both short-term and long-term variations in the light curve of the eclipsing system OGLE-LMC-ECL-14413, with a particular focus on the unusual reversals in eclipse depth. We aim to clarify the role of the accretion disk in these fluctuations, especially in long-cycle changes spanning hundreds of days. Additionally, we seek to determine the evolutionary stage of the system and gain insights into the internal structure of its stellar components. We analyzed photometric time series from the Optical Gravitational Lensing Experiment (OGLE) project in the I and V bands, and from the MAssive Compact Halo Objects project in the BM and RM bands, covering a period of 30.85 years. Using light curve data from 27 epochs, we constructed models of the accretion disk. An optimized simplex algorithm was employed to solve the inverse problem, deriving the best-fit parameters for the stars, orbit, and disk. We also utilized the Modules for Experiments in Stellar Astrophysics software to assess the evolutionary stage of the binary system, investigating the progenitors and potential future developments. We found an orbital period of 38.15917(54) d and a long-term cycle of approximately 780 d. Temperature, mass, radius, and surface gravity values were determined for both stars. The photometric orbital cycle and the long-term cycle are consistent with a disk containing variable physical properties, including two shock regions. The disk encircles the more massive star and the system brightness variations align with the long-term cycle at orbital phase 0.25. Our mass transfer rate calculations correspond to these brightness changes. \texttt{MESA} simulations indicate weak magnetic fields in the donor star's subsurface, which are insufficient to influence mass transfer rates significantly.

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arXiv2024

Two black widow pulsars in the optical and X-rays

Context. Two millisecond pulsars, PSR J1513$-$2550 and PSR J2017$-$1614, with spin periods of about 2.1 and 2.3 ms were recently discovered in the radio and $γ$-rays and classified as black widow pulsars in tight binary stellar systems with orbital periods of about 4.3 and 2.3 h. Aims. Our goals are to reveal fundamental parameters of both systems and their binary components using multi-wavelength observations. Methods. We carried out the first time-series multi-band optical photometry of the objects with the 2.1-metre telescope of the Observatorio Astronómico Nacional San Pedro Mártir, the 6.5-metre \magel-1 telescope, and the 10.4-metre Gran Telescopio Canarias. To derive the parameters of both systems, we fitted the obtained light curves with a model assuming heating of the companion by the pulsar. We also analysed archival X-ray data obtained with the XMM-Newton observatory. Results. For the first time, we firmly identified J1513$-$2550 in the optical and both pulsars in X-rays. The optical light curves of both systems have a single peak per orbital period with peak-to-peak amplitude of $\gtrsim2$ magnitudes. The J2017$-$1614 light curves are symmetric, while J1513$-$2550 demonstrates strong asymmetry whose nature remains unclear. Conclusions. We constrained the orbital inclinations, pulsar masses, companion temperatures and masses, as well as the distances to both systems. We also conclude that J2017$-$1614 may contain a massive neutron star of 2.4$\pm$0.6 M$_{\odot}$. The X-ray spectra of both sources can be fitted by power laws with parameters typical for black widow systems.

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arXiv2024

Characterizing NGC 6383: A study of pre-main sequence stars, mass segregation, and age using Gaia DR3 and 2MASS

The presence of pre-main-sequence and low-mass stars, combined with the new data from Gaia DR3 and with 2MASS, significantly enhances the relevance of studying this cluster. We aim to accurately identify cluster members, determine fundamental parameters, assess mass segregation, and establish precise age and distance using Gaia DR3 and 2MASS data. We employed Bayesian analysis and machine learning techniques, including the Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) for member identification, the No-U-Turn Sampler (NUTS) from PyMC for modeling, the Sagitta neural network for the identification and age estimation of pre-main sequence stars, and ASteCA for isochrone fitting. We identified 254 probable cluster members with a mode cluster age of $3.53^{+1.40}_{-1.00}$ Myr and a distance of $1.11\pm 0.06$ kpc. The core and tidal radius were determined to be $1.95 \pm 0.19$ and $40.4 \pm 14.3\,\mathrm{arcmin}$, respectively. The analysis revealed primordial mass segregation among binary stars, indicating that NGC 6383 is not fully relaxed. The color magnitude diagram (CMD) shows a well-defined main sequence and a population of pre-main sequence stars, suggesting recent star formation activity from approximately 1 to 6 Myr ago. The software used for this investigation is released with the paper. Our analysis provides updated parameters for NGC 6383, confirming relative recent star formation and mass segregation, and demonstrating the effectiveness of combining advanced computational techniques with traditional methods for studying stellar clusters.

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arXiv2023

Simulations of dynamo action in slowly rotating M dwarfs: Dependence on dimensionless parameters

The aim of this study is to explore the magnetic and flow properties of fully convective M dwarfs as a function of rotation period Prot and magnetic Reynolds ReM and Prandlt numbers PrM. We performed three-dimensional simulations of fully convective stars using a star-in-a-box setup. This setup allows global dynamo simulations in a sphere embedded in a Cartesian cube. The equations of non-ideal magnetohydrodynamics were solved with the Pencil Code. We used the stellar parameters of an M5 dwarf with 0.21M_odot at three rotation rates corresponding to rotation periods (Prot): 43, 61 and 90 days, and varied the magnetic Prandtl number in the range from 0.1 to 10. We found systematic differences in the behaviour of the large-scale magnetic field as functions of rotation and PrM. For the simulations with Prot = 43 days and PrM <= 2, we found cyclic large-scale magnetic fields. For PrM > 2 the cycles vanish and field shows irregular reversals. In simulations with Prot = 61 days for PrM <= 2 the cycles are less clear and the reversal are less periodic. In the higher-PrM cases, the axisymmetric mean field shows irregular variations. For the slowest rotation case with Prot = 90 days, the field has an important dipolar component for PrM <= 5. For the highest PrM the large-scale magnetic field is predominantly irregular at mid-latitudes, with quasi-stationary fields near the poles. For the simulations with cycles, the cycle period length slightly increases with increasing ReM.

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arXiv2023

V4142 Sgr: a Double Periodic Variable with an accretor surrounded by the accretion-disk's atmosphere

Context: A detailed study of the close interacting binary V4142\,Sgr based on photometric and spectroscopic analysis is presented.This system belongs to the enigmatic class of Algol-like variables showing a long photometric cycle of unknown nature. Aims: Performing photometric data-mining and spectroscopic observations covering the orbital cycle, we obtain the orbital parameters and the stellar properties of the binary system, along with the physical properties of the accretion disk located around the hot star. Insights on the evolutive path of the system are obtained. Methods: The light curve was modeled through an inverse modeling method using a theoretical light curve of the binary system, considering the light curve contribution of both stars and the accretion disk of the hot star to obtain the fundamental parameters. To constrain the main stellar parameters the mass ratio was fixed, as well as the donor temperature using the obtained values from our spectroscopic analysis including deblending methods to isolate the spectral lines of the stellar components. The system parameters were compared with a grid of binary star evolutive models in order to get insights on the evolutionary history of the system. Results: The orbital period and the long cycle were re-calculated and found to be of $30.633 \pm 0.002 ~\mathrm{days}$ and $1201 \pm 14 ~\mathrm{days}$. The spectral analysis reveals H$α$ double emission with a persistent $V \leq R$ asymmetry which is considered evidence of a possible wind emergin from the hotspot region...

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arXiv2022

Detailed stellar activity analysis and modelling of GJ 832: Reassessment of the putative habitable zone planet GJ 832c

Context. Gliese 832 (GJ 832) is an M2V star hosting a massive planet on a decade-long orbit, GJ 832b, discovered by radial velocity (RV). Later, a super Earth or mini-Neptune orbiting within the stellar habitable zone was reported (GJ 832c). The recently determined stellar rotation period (45.7 $\pm$ 9.3 days) is close to the orbital period of putative planet c (35.68 $\pm$ 0.03 days). Aims. We aim to confirm or dismiss the planetary nature of the RV signature attributed to GJ 832c, by adding 119 new RV data points, new photometric data, and an analysis of the spectroscopic stellar activity indicators. Additionally, we update the orbital parameters of the planetary system and search for additional signals. Methods. We performed a frequency content analysis of the RVs to search for periodic and stable signals. Radial velocity time series were modelled with Keplerians and Gaussian process (GP) regressions alongside activity indicators to subsequently compare them within a Bayesian framework. Results. We updated the stellar rotational period of GJ 832 from activity indicators, obtaining $37.5^{+1.4}_{-1.5}$ days, improving the precision by a factor of 6. The new photometric data are in agreement with this value. We detected an RV signal near 18 days (FAP < 4.6%), which is half of the stellar rotation period. Two Keplerians alone fail at modelling GJ 832b and a second planet with a 35-day orbital period. Moreover, the Bayesian evidence from the GP analysis of the RV data with simultaneous activity indices prefers a model without a second Keplerian, therefore negating the existence of planet c.

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arXiv2022

Spectroscopy of the massive interacting binary UU Cassiopeiae

Context. The eclipsing close binary UU Cas is an interacting massive double-periodic system with a gainer star partly hidden in an accretion disk. Aims. In order to study the physics of the accretion process in greater detail, along with the structure and dynamics of the circumstellar matter in the system, we supplement our previous results obtained from photometry with an analysis of the spectra of UU Cas. Methods. We collected all available spectra used in previous publications on UU Cas and we acquired new ones. The method of disentangling was applied to this set of spectra spanning the years 2008-2021. The orbital parameters were disentangled and a fit of the separated component spectra by synthetic ones has been used to determine the physical parameters of the component stars. We compared the results to models of the evolution of interacting binaries. Results. We found that in addition to the dominant role of the donor star and a weak contribution of the gainer, the line profiles are strongly influenced by the circumstellar matter. The absorption lines reveal a presence of a disk wind emanating above the orbital plane. The variability of Hα emission yields evidence of changes in the structure of the circumstellar matter on a timescale of several orbital periods.

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arXiv2021

Fundamental parameters of the eclipsing binary DD CMa and evidence for mass exchange

We present a detailed photometric and spectroscopic analysis of DD CMa, based on published survey photometry and new spectroscopic data. We find an improved orbital period of $P_\mathrm{o}= 2.0084530 \pm 0.0000006 ~\mathrm{d}$. Our spectra reveal H$β$ and H$α$ absorptions with weak emission shoulders and we also find color excess in the WISE multiband photometry, interpreted as signatures of circumstellar matter. We model the $V$-band orbital light curve derived from the ASAS and ASAS-SN surveys, assuming a semidetached configuration and using the mass ratio and temperature of the hotter star derived from our spectroscopic analysis. Our model indicates that the system consists of a B 2.5 dwarf and a B 9 giant of radii 3.2 and 3.7 $\mathrm{R_{\odot}}$, respectively, orbiting in a circular orbit of radius 6.75 $\mathrm{R_{\odot}}$. We also found $M_{\mathrm{c}} = 1.7 \pm 0.1 ~\mathrm{M_{\odot}}$, $T_{\mathrm{c}} = 11350 \pm 100 ~\mathrm{K}$ and $M_{\mathrm{h}} = 6.4 \pm 0.1 ~\mathrm{M_{\odot}}$, $T_{\mathrm{h}} = 20000 \pm 500 ~\mathrm{K}$, for the cooler and hotter star, respectively. We find broad single emission peaks in H$α$ and H$β$ after subtracting the synthetic stellar spectra. Our results are consistent with mass exchange between the stars, and suggest the existence of a stream of gas being accreted onto the early B-type star.

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arXiv2021

Stellar and accretion disk parameters of the close binary HD 50526

We present a photometric and spectroscopic study of HD 50526, an ellipsoidal binary member of the group Double Periodic Variable stars. Performing data-mining in photometric surveys and conducting new spectroscopic observations with several spectrographs during 2008 to 2015, we obtained orbital and stellar parameters of the system. The radial velocities were analyzed with the genetic PIKAIA algorithm, whereas Doppler tomography maps for the H$α$ and H$β$ lines were constructed with the Total Variation Minimization code. An optimized simplex-algorithm was used to solve the inverse-problem adjusting the light curve with the best stellar parameters for the system. We find an orbital period of $6.701 \pm 0.001 ~\mathrm{d}$ and a long photometric cycle of $191 \pm 2 ~\mathrm{d}$. We detected the spectral features of the coldest star, and modeled it with a $\log{g} = 2.79 \pm 0.02 ~\mathrm{dex}$ giant of mass $1.13 \pm 0.02 ~\mathrm{M_{\odot}}$ and effective temperature $10500 \pm 125 ~\mathrm{K}$. In addition, we determine a mass ratio $q= 0.206 \pm 0.033$ and that the hot star is a B-type dwarf of mass $5.48 \pm 0.02 ~\mathrm{M_{\odot}}$. The $V$-band orbital light curve can be modeled including the presence of an accretion disk around the hotter star. This fills the Roche lobe of the hotter star, and has a radius $14.74 \pm 0.02 ~\mathrm{R_{\odot}}$ and temperature at the outer edge $9400 ~\mathrm{K}$. Two bright spots located in the disk account for the global morphology of the light curve. The Doppler tomography maps of H$α$ and H$β$, reveal complex structures of mass fluxes in the system.

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arXiv2021

Masses and compositions of three small planets orbiting the nearby M dwarf L231-32 (TOI-270) and the M dwarf radius valley

We report on precise Doppler measurements of L231-32 (TOI-270), a nearby M dwarf ($d=22$ pc, $M_\star = 0.39$ M$_\odot$, $R_\star = 0.38$ R$_\odot$), which hosts three transiting planets that were recently discovered using data from the Transiting Exoplanet Survey Satellite (TESS). The three planets are 1.2, 2.4, and 2.1 times the size of Earth and have orbital periods of 3.4, 5.7, and 11.4 days. We obtained 29 high-resolution optical spectra with the newly commissioned Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations (ESPRESSO) and 58 spectra using the High Accuracy Radial velocity Planet Searcher (HARPS). From these observations, we find the masses of the planets to be $1.58 \pm 0.26$, $6.15 \pm 0.37$, and $4.78 \pm 0.43$ M$_\oplus$, respectively. The combination of radius and mass measurements suggests that the innermost planet has a rocky composition similar to that of Earth, while the outer two planets have lower densities. Thus, the inner planet and the outer planets are on opposite sides of the `radius valley' -- a region in the radius-period diagram with relatively few members, which has been interpreted as a consequence of atmospheric photo-evaporation. We place these findings into the context of other small close-in planets orbiting M dwarf stars, and use support vector machines to determine the location and slope of the M dwarf ($T_\mathrm{eff} < 4000$ K) radius valley as a function of orbital period. We compare the location of the M dwarf radius valley to the radius valley observed for FGK stars, and find that its location is a good match to photo-evaporation and core-powered mass loss models. Finally, we show that planets below the M dwarf radius valley have compositions consistent with stripped rocky cores, whereas most planets above have a lower density consistent with the presence of a H-He atmosphere.

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arXiv2021

PSR B0656+14: the unified outlook from the infrared to X-rays

We report detection of PSR B0656$+$14 with the Gran Telescopio Canarias in narrow optical $F657$, $F754$, $F802$, and $F902$ and near-infrared $JHK_s$ bands. The pulsar detection in the $K_s$ band extends its spectrum to 2.2 $μ$m and confirms its flux increase towards the infrared. We also present a thorough analysis of the optical spectrum obtained by us with the VLT. For a consistency check, we revised the pulsar near-infrared and narrow-band photometry obtained with the \textit{HST}. We find no narrow spectral lines in the optical spectrum. We compile available near-infrared-optical-UV and archival 0.3-20keV X-ray data and perform a self-consistent analysis of the rotation phase-integrated spectrum of the pulsar using unified spectral models. The spectrum is best fitted by the four-component model including two blackbodies, describing the thermal emission from the neutron star surface and its hot polar cap, the broken power-law, originating from the pulsar magnetosphere, and an absorption line near $\sim$0.5 keV detected previously. The fit provides better constraints on the model parameters than using only a single spectral domain. The derived surface temperature is $T_{NS}^{\infty}=7.9(3)\times10^5$K. The intrinsic radius (7.8-9.9 km) of the emitting region is smaller than a typical neutron star radius (13km) and suggests a nonuniform temperature distribution over the star surface. In contrast, the derived radius of the hot polar cap is about twice as large as the `canonical' one. The spectrum of the nonthermal emission steepens from the optical to X-rays and has a break near 0.1 keV. The X-ray data suggest the presence of another absorption line near 0.3keV.

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arXiv2020

New insights on the massive interacting binary UU Cassiopeiae

We present the results of the study of the close binary UU Cassiopeiae based on previously published multi wavelength photometric and spectroscopic data. Based on eclipse timings of the last 117 years, we find an improved orbital period of $\rm P_{o} = 8.519296(8)$ d. In addition, we find a long cycle of length $T$ $\sim$ 270 d in the $I_c$-band data. There is no evidence for orbital period change during the last century, suggesting that the rate of mass loss from the system or mass exchange between the stars should be small. Sporadic and rapid brightness drops of up to $Δ$$V$ = 0.3 mag are detected during the whole orbital cycle and infrared photometry clearly suggests the presence of circumstellar matter. We model the orbital light curve of 11 published datasets fixing the mass ratio and cool star temperature from previous spectroscopic work; $q$= 0.52 and $T_c$= 22 700 K. We find a system seen at angle 74 degrees with a stellar separation of 52 ${\rm R_{\odot}}$, a temperature for the hotter star $T_h$= 30 200 $K$ and stellar masses 17.4 and 9 ${\rm M_{\odot}}$ , radii 7.0 and 16.9 ${\rm R_{\odot}}$ and surface gravities log g = 3.98 and 2.94, for the hotter and cooler star, respectively. We find an accretion disk surrounding the more massive star, with a radius of 21 ${\rm R_{\odot}}$ and vertical thickness in its outer edge of 6.5 ${\rm R_{\odot}}$, mostly occulting the hotter star. Two active regions hotter than the surrounding disk are found, one located roughly in the expected position where the stream impacts the disk and the other one in the opposite side of the disk. Changes are observed in parameters of the disk and spots in different datasets.

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arXiv2020

Long photometric cycle and disk evolution in the $β$ Lyrae type binary OGLE-BLG-ECL-157529

The subtype of hot algol semidetached binaries dubbed Double Periodic Variables (DPVs) are characterized by a photometric cycle longer than the orbital one, whose nature has been related to a magnetic dynamo in the donor component controlling the mass transfer rate. We aim to understand the morphologic changes observed in the light curve of OGLE-BLG-ECL-157529 that are linked to the long cycle. In particular, we want to explain the changes in relative depth of primary and secondary eclipses. We analyze $I$ and $V$-band OGLE photometric times series spanning 18.5 years and model the orbital light curve. We find that OGLE-BLG-ECL-157529 is a new eclipsing Galactic DPV of orbital period 24\fd8, and that its long cycle length decreases in amplitude and length during the time baseline. We show that the changes of the orbital light curve can be reproduced considering an accretion disk of variable thickness and radius, surrounding the hottest stellar component. Our models indicate changes in the temperatures of hot spot and bright spot during the long cycle, and also in the position of the bright spot. This, along with the changes in disk radius might indicate a variable mass transfer in this system.

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arXiv2020

A hot terrestrial planet orbiting the bright M dwarf L 168-9 unveiled by TESS

We report the detection of a transiting super-Earth-sized planet (R=1.39+-0.09 Rearth) in a 1.4-day orbit around L 168-9 (TOI-134),a bright M1V dwarf (V=11, K=7.1) located at 25.15+-0.02 pc. The host star was observed in the first sector of the Transiting Exoplanet Survey Satellite (TESS) mission and, for confirmation and planet mass measurement, was followed up with ground-based photometry, seeing-limited and high-resolution imaging, and precise radial velocity (PRV) observations using the HARPS and PFS spectrographs. Combining the TESS data and PRV observations, we find the mass of L168-9 b to be 4.60+-0.56 Mearth, and thus the bulk density to be 1.74+0.44-0.33 times larger than that of the Earth. The orbital eccentricity is smaller than 0.21 (95% confidence). This planet is a Level One Candidate for the TESS Mission's scientific objective - to measure the masses of 50 small planets - and is one of the most observationally accessible terrestrial planets for future atmospheric characterization.

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arXiv2019

New Double Periodic Variable Stars in the ASAS-SN Catalog

We report the discovery of 3 new Double Periodic Variables based on the analysis of ASAS-SN light curves: GSD J11630570-510306, V593 Sco and TYC 6939-678-1. These systems have orbital periods between 10 and 20 days and long cycles between 300 and 600 days.

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