Early-type stars are short lived and scarce in comparison with other types. Based on the recently released catalogs of early type stars from the largest LAMOST spectroscopic survey, the intrinsic colors of the stars with effective temperature up to 32,000\,K are determined for the bands from ultraviolet to infrared by using the blue-edge method. Analytic relations are derived for the intrinsic color index with the effective temperature for the \emph{WISE}, 2MASS, \emph{Gaia}, APASS, SDSS, Pan-STARRS1, and \emph{GALEX} bands. The results are generally consistent with previous works. In addition, the intrinsic colors of O-type dwarfs and OB supergiants are roughly estimated.
Intrinsic sequences of luminosity V and III stars in the J-H vs. H-Ks diagram of the 2MASS system are determined using about 1250 unreddened and dereddened stars. Intrinsic color indices for MK spectral classes are tabulated and compared with the results in other JHK systems.
The majority of brown dwarfs show some level of photometric or spectro-photometric variability in different wavelength ranges. This variability allow us to trace the 3D atmospheric structures of variable brown dwarfs and directly-imaged exoplanets with radiative-transfer models and mapping codes. Nevertheless, to date, we do not have an informed method to pre-select the brown dwarfs that might show a higher variability amplitude for a thorough variability study. In this work, we designed and tested near-infrared spectral indices to pre-select the most likely variable mid- and late-T dwarfs, wh…
We used four known chromospheric activity indicators to measure long-term activity variations in a sample of 23 M-dwarf stars from the HARPS planet search program. We compared the indices using weighted Pearson correlation coefficients and found that in general (i) the correlation between $S_{CaII}$ and \ion{Na}{i} is very strong and does not depend on the activity level of the stars, (ii) the correlation between our $S_{CaII}$ and H$α$ seems to depend on the activity level of the stars, and (iii) there is no strong correlation between $S_{CaII}$ and \ion{He}{i} for these type of stars.
Aims. We try to identify ultra-cool dwarfs from the seventh Data Release of the Sloan Digital Sky Survey (SDSS DR7) with SDSS i-z and r-z colors. We also obtain proper motion data from SDSS, 2MASS, and UKIDSS and improve spectral typing from SDSS and 2MASS photometric colors. Methods. We selected ultra-cool dwarf candidates from the SDSS DR7 with new photometric selection criteria, which are based on a parameterization study of known L and T dwarfs. The objects are then cross-identified with the Two Micron All Sky Survey and the Fourth Data Release of the UKIRT Infrared Deep Sky Survey (UKIDSS…
We report the results from spectroscopic observations of 113 ultra-wide, low-mass binary systems, composed largely of M0--M3 dwarfs, from the SLoWPoKES catalog of common proper motion pairs identified in the Sloan Digital Sky Survey. Radial velocities of each binary member were used to confirm that they are co-moving and, consequently, to further validate the high fidelity of the SLoWPoKES catalog. Ten stars appear to be spectroscopic binaries based on broad or split spectral features, supporting previous findings that wide binaries are likely to be hierarchical systems. We measured the Hα equ…
We present a sample of 484 L dwarfs, 210 of which are newly discovered from the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic database. We combine this sample with known L dwarfs to investigate their $izJHK_S$ colors. Our spectroscopically selected sample has $\sim$0.1 magnitude bluer median $J-K_S$ colors at a given spectral type (for L0 to L4) than previously known L dwarfs, which reflects a bias towards redder L dwarfs in past selection criteria. We present photometric distance relations based on $i-z$ and $i-J$ colors and derive distances to our L dwarf sample. We combine th…
We present the colors and activity of ultracool (M7-L8) dwarfs from the Tenth Data Release of the Sloan Digital Sky Survey (SDSS). We combine previous samples of SDSS M and L dwarfs with new data obtained from the Baryon Oscillation Sky Survey (BOSS) to produce the BOSS Ultracool Dwarf (BUD) sample of 11820 M7-L8 dwarfs. By combining SDSS data with photometry from the Two Micron All Sky Survey and the Wide-Field Infrared Sky Explorer mission, we present ultracool dwarf colors from $i-z$ to $W2-W3$ as a function of spectral type, and extend the SDSS-2MASS-WISE color locus to include ultracool d…
The Gaia M-dwarf gap is a significant under-density of stars observed near $M_G = 10.2$ in a color-magnitude diagram for stars within 200 pc of the Sun. It has been proposed that the gap is the manifestation of structural instabilities within stellar interiors due to non-equilibrium $^{3}$He fusion prior to some stars becoming fully convective. To test this hypothesis, we use Dartmouth stellar evolution models, MARCS model atmospheres, and simple stellar population synthesis to create synthetic $M_G$-($G_{\rm BP} - G_{\rm RP})$ color-magnitude diagrams. We confirm that the proposed $^{3}$He in…
We present FEROS--Lick/SDSS, an empirical database of Lick/SDSS spectral indices of FGK stars to be used in population synthesis projects for discriminating different stellar populations within the integrated light of galaxies and globular clusters. From about 2500 FEROS stellar spectra obtained from the ESO Science Archive Facility we computed line--strength indices for 1085 non--supergiant stars with atmospheric parameter estimates from the AMBRE project. Two samples of 312 {\it dwarfs} and of 83 {\it subgiants} with solar chemical composition and no significant $α$--element abundance enhanc…
We present a spectroscopic and photometric calibration to derive effective temperatures $T_{\mathrm{eff}}$ and metallicities [Fe/H] for M dwarfs, based on a Principal Component Analysis of 147 spectral indices measured off moderate resolution $R \sim 11\,000$), high S/N ($>100$) spectra in the $λλ$ 8390-8834 region, plus the J$-$H color. Internal uncertainties, estimated by the residuals, are 81 K and 0.12 dex, respectively, for $T_{\mathrm{eff}}$ and [Fe/H], the calibrations being valid for 3050 K $< T_{\mathrm{eff}} <$ 4100 K and $-$0.45 $<$ [Fe/H] $<$ $+$0.50 dex. The PCA calibration is a c…
We present a spectroscopic catalog of 67082 M dwarfs from the LAMOST pilot survey. For each spectrum of the catalog, spectral subtype, radial velocity, equivalent width of H$α$, a number of prominent molecular band indices and the metal sensitive parameter $ζ$ are provided . Spectral subtype have been estimated by a remedied Hammer program (Original Hammer: Covey et al. 2007), in which indices are reselected to obtain more accurate auto-classified spectral subtypes. All spectra in this catalog have been visually inspected to confirm the spectral subtypes. Radial velocities have been well measu…
Atmospheric and evolutionary models for low-mass stars rely on approximate assumptions on the physics of the stellar structure and the atmospheric radiative transfer. This leads to biased theoretical predictions on the photospheric Spectral Energy Distributions of Pre-Main Sequence (PMS) stars, and affects the derivation of stellar parameters from photometric data. Our goal is to correct the biases present in the theoretical predictions for the near-IR photometry of low-mass PMS stars. Using empirical intrinsic IR colors, we assess the accuracy of current synthetic spectral libraries and evolu…
We present spectroscopic observations confirming the identification of hot white dwarfs among UV-bright sources from the Sandage Two-color Survey of the Galactic plane and listed in the Lanning (Lan) catalog of such sources. A subsample of 213 UV bright Lan sources have been identified as candidate white dwarfs based on the detection of a significant proper motion. Spectroscopic observations of 46 candidates with the KPNO 2.1m telescope confirm 30 sources to be hydrogen white dwarfs with subtypes in the DA1-DA6 range, and with one of the stars (Lan 161) having an unresolved M dwarf as a compan…
We present a statistical parallax analysis of low-mass dwarfs from the Sloan Digital Sky Survey (SDSS). We calculate absolute r-band magnitudes (M_r) as a function of color and spectral type, and investigate changes in M_r with location in the Milky Way. We find that magnetically active M dwarfs are intrinsically brighter in M_r than their inactive counterparts at the same color or spectral type. Metallicity, as traced by the proxy zeta, also affects M_r, with metal poor stars having fainter absolute magnitudes than higher metallicity M dwarfs at the same color or spectral type. Additionally, …
We aim at building a method that efficiently identifies young low-mass stars and brown dwarfs from low-resolution near-infrared spectra, by studying gravity-sensitive features and their evolution with age. We built a dataset composed of all publicly available ($\sim$2800) near-infrared spectra of dwarfs with spectral types between M0 and L3. First, we investigate methods for the derivation of the spectral type and extinction using comparison to spectral templates, and various spectral indices. Then, we examine gravity-sensitive spectral indices and apply machine learning methods, in order to e…
Motivated by the recent detection of single and binary He-core white dwarfs in metal-rich clusters, we present a full set of evolutionary calculations and colors appropriate for the study of such white dwarfs. The paper is also aimed at investigating whether stable hydrogen burning may constitute a main source of energy for massive He-core white dwarfs resulting from high-metallicity progenitors. White dwarf sequences are derived by taking into account the evolutionary history of progenitor stars with supersolar metallicities. We also incorporate a self-consistent, time-dependent treatment of …
Gravity-sensitive Spectral Indices in Ultracool Dwarfs: Investigating Correlations with Metallicity and Planet Occurrence using SpeX and FIRE Observations
本文通过 SpeX 和 FIRE 近红外光谱分析56颗超冷矮星的重力敏感指数，发现 FeH_z 与金属丰度呈3.3σ反相关，但重力类别与行星出现率无显著关联，提示解释行星宿主时需谨慎。
We use spectra from CARMENES, the Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs, to search for periods in chromospheric indices in 16 M0 to M2 dwarfs. We measure spectral indices in the H$α$, the Ca II infrared triplet (IRT), and the Na I D lines to study which of these indices are best-suited to find rotation periods in these stars. Moreover, we test a number of different period-search algorithms, namely the string length method, the phase dispersion minimisation, the generalized Lomb-Scargle periodogram, and the Gaussian p…
Disks around brown dwarfs (BDs) are excellent laboratories to study the first steps of planet formation in cold and low-mass disk conditions. The radial-drift velocities of dust particles in BD disks are higher than in disks around more massive stars. Therefore, BD disks are expected to be more depleted in millimeter-sized grains compared to disks around T Tauri or Herbig Ae/Be stars. However, recent millimeter observations of BD disks revealed low millimeter spectral indices, indicating the presence of large grains in these disks and challenging models of dust evolution. We present 3\,mm phot…
We present a large dataset of high cadence dMe flare light curves obtained with custom continuum filters on the triple-beam, high-speed camera system ULTRACAM. The measurements provide constraints for models of the NUV and optical continuum spectral evolution on timescales of ~1 second. We provide a robust interpretation of the flare emission in the ULTRACAM filters using simultaneously-obtained low-resolution spectra during two moderate-sized flares in the dM4.5e star YZ CMi. By avoiding the spectral complexity within the broadband Johnson filters, the ULTRACAM filters are shown to characteri…
Aims. Other stars are known to have magnetic cycles similar to that of the Sun. The relationship between these activity variations and the observed radial-velocity is still not satisfactorily understood. In this first paper our aim is to assess the long-term activity variations in the low end of the main sequence, having in mind a planetary search perspective. Methods. We used a sample of 30 M0-M5.5 stars from the HARPS M-dwarf planet search program with a median timespan of observations of 5.2 years. We computed chromospheric activity indicators based on the Ca II H and K, Hα, He I D3, and Na…
We present the results of a Keck/NIRSPEC follow-up survey of thirteen late-type T dwarfs (T6-T9), twelve of which have unusually red or blue J-H colors. Previous work suggests that J-H color outliers may represent the high-gravity, low-metallicity (old) and low-gravity, solar-metallicity (young) extremes of the late-type T dwarf population. We use medium-resolution Y- and H-band spectroscopy to probe regions of T dwarf atmospheres that are more sensitive to gravity and metallicity variations than the J band. We find that the spectral morphologies of our sample are largely homogeneous, with pea…
We combine 131 new medium-resolution (R~2000) J-band spectra of M, L, and T dwarfs from the Keck NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS) with 97 previously published BDSS spectra to study surface-gravity-sensitive indices for 228 low-mass stars and brown dwarfs spanning spectral types M5-T9. Specifically, we use an established set of spectral indices to determine surface gravity classifications for all M6-L7 objects in our sample by measuring equivalent widths (EW) of the K I lines at 1.1692, 1.1778, 1.2529 um, and the 1.2 um FeHJ absorption index. Our results are consistent with previ…
We have developed a method for estimating the orbital periods of dwarf novae from the Sloan Digital Sky Survey (SDSS) colors in quiescence using an artificial neural network. For typical objects below the period gap with sufficient photometric accuracy, we were able to estimate the orbital periods with an accuracy to a 1 sigma error of 22 %. The error of estimation is worse for systems with longer orbital periods. We have also developed a neural-network-based method for categorical classification. This method has proven to be efficient in classifying objects into three categories (WZ Sge type,…
We present a critical review of the determination of fundamental parameters of white dwarfs discovered by the Gaia mission. We first reinterpret color-magnitude and color-color diagrams using photometric and spectroscopic information contained in the Montreal White Dwarf Database (MWDD), combined with synthetic magnitudes calculated from a self-consistent set of model atmospheres with various atmospheric compositions. The same models are then applied to measure the fundamental parameters of white dwarfs using the so-called photometric technique, which relies on the exquisite Gaia trigonometric…
We discover a late-type L dwarf, WISEP J060738.65+242953.4 (W0607+2429), by comparing the Wide-field Infrared Survey Explorer (WISE) preliminary data release to the Two Micron All Sky Survey (2MASS) in search of high proper motion objects (>0.3" yr^-1). W0607+2429 was found to have a proper motion of 0.57 +/- 0.02" yr^-1. Based on colors and color-color diagrams using 2MASS and Sloan Digital Sky Survey (SDSS) photometry, we estimate the spectral type (optical) to be L8 within a spectral sub-type. Based on the spectral type estimated we find W0607+2429 to have a distance of 7.8^(+1.4)_(-1.2) pc…
We report the discovery of 87 new T dwarfs uncovered with the Wide-field Infrared Survey Explorer (WISE) and three brown dwarfs with extremely red near-infrared colors that exhibit characteristics of both L and T dwarfs. Two of the new T dwarfs are likely binaries with L7+/-1 primaries and mid-type T secondaries. In addition, our follow-up program has confirmed 10 previously identified T dwarfs and four photometrically-selected L and T dwarf candidates in the literature. This sample, along with the previous WISE discoveries, triples the number of known brown dwarfs with spectral types later th…
We present our photometric studies of the newly discovered optical transient, OT J012059.6+325545, which underwent a large outburst between 2010 November and 2011 January. The amplitude of the outburst was about 8 mag. We performed simultaneous multi-color photometry by using g', Rc, and i'-band filters from the early stage of the outburst. The time resolved photometry during the early stage revealed periodic variations with double-peaked profiles, which are referred to as early superhumps, with amplitudes of about 0.08 mag. After the rapid fading from the main outburst, we found rebrightening…
Among the greatest challenges in understanding ultra-cool brown dwarf and exoplanet atmospheres is the evolution of cloud structure as a function of temperature and gravity. In this study, we present the rotational modulations of GU Psc b -- a rare mid-T spectral type planetary-mass companion at the end of the L/T spectral type transition. Based on the HST/WFC3 1.1-1.67$\rm\, μm$ time-series spectra, we observe a quasi-sinusoidal light curve with a peak-to-trough flux variation of 2.7 % and a minimum period of eight hours. The rotation-modulated spectral variations are weakly wavelength-depend…
Due to the highly degeneracy of electrons in white dwarf stars, we expect that the relativistic effects play very important role in these stars. In the present article, we study the properties of the condensed matter in white dwarfs using Newtonian and relativistic polytropic fluid sphere. Two polytropic indices (namely n=3 and n=1.5) are proposed to investigate the physical characteristics of the models. We solve the Lane-Emden equations numerically.. The results show that the relativistic effect is small in white dwarf stars.
The Polar Vortex Hypothesis: Evolving, Spectrally Distinct Polar Regions Explain Short- and Long-term Light Curve Evolution and Color-Inclination Trends in Brown Dwarfs and Giant Exoplanets
2013 FY27 is the ninth intrinsically brightest Trans-Neptunian Object (TNO). We observed 2013 FY27 at thermal wavelengths with ALMA and in the optical with Magellan to determine its size and albedo for the first time and compare it to other dwarf planets. The geometric albedo of 2013 FY27 was found to be 0.17 -0.030+0.045, giving an effective diameter of D = 765 +80-85 km. 2013 FY27 has a size within the transition region between the largest few TNOs that have higher albedos and higher densities than smaller TNOs. No significant short-term optical light curve was found, with variations less th…
We present the discovery of a very cold, very low mass, nearby brown dwarf using data from the NASA Wide-field Infrared Survey Explorer (WISE). The object, WISE J064723.23-623235.5, has a very red WISE color of W1-W2 > 3.77 mag and a very red Spitzer Space Telescope color of ch1-ch2 = 2.82+/-0.09 mag. In J_MKO-ch2 color (7.58+/-0.27 mag) it is one of the two or three reddest brown dwarfs known. Our grism spectrum from the Hubble Space Telescope (HST) confirms it to be the seventeenth Y dwarf discovered, and its spectral type of Y1+/-0.5 makes it one of the four latest-type Y dwarfs classified.…
We report resolved near-infrared imaging and spectroscopic observations of the T8.5 binary WISEP J045853.90+643452.6AB obtained with Keck/NIRC2, Keck/OSIRIS and the Keck Laser Guide Star Adaptive Optics system. These data confirm common proper and radial motion for the two components, and we see the first indications of orbital motion (mostly radial) for this system. H-band spectroscopy identifies both components as very late-type brown dwarfs with strong H2O and CH4 absorption. The spectrum of WISE J0458+6434B also exhibits a compelling signature of NH3 absorption over 1.52-1.54 micron when c…
Using Keck laser guide star adaptive optics imaging, we have found that the T9 dwarf WISE J1217+1626 and T8 dwarf WISE J1711+3500 are exceptional binaries, with unusually wide separations (~0.8 arcsec, 8-15 AU), large near-IR flux ratios (~2-3 mags), and small mass ratios (~0.5) compared to previously known field ultracool binaries. Keck/NIRSPEC H-band spectra give a spectral type of Y0 for WISE J1217+1626B, and photometric estimates suggest T9.5 for WISE J1711+3500B. The WISE J1217+1626AB system is very similar to the T9+Y0 binary CFBDSIR J1458+1013AB; these two systems are the coldest known …
We investigate the planetary transit detectability in the presence of stellar rotational activity from light curves for young M-dwarfs and estimate improvements of the detection at near-infrared (NIR) wavelengths. Making maps of the transit signal detection efficiency over the orbital period and planetary radius with light curves of members of four clusters, Hyades, Praesepe, Pleiades, and Upper Scorpius observed by the K2 mission, we evaluate the detectability for the rotation period and modulation semi-amplitude. We find that the detection efficiency remarkably decreases to about 20% for rap…
Brown dwarfs undergo little change in near-infrared luminosity while cooling from L to T spectral types, making the L/T transition (spectral types $\approx$L9--T6) an ideal region to examine the differences in photometry for binary and single brown dwarfs. We investigated the mean absolute magnitudes for binaries and singles with parallaxes as a function of J-K color in the L/T transition. Overall, binaries are on average $1-2σ$ brighter than singles of the same color. We discuss the implications for candidate binaries that are apparent spectral blends which span a broad range of luminosities,…
We report the discovery of an unusually blue L5 dwarf within 10 pc of the Sun from a search of Sloan Digital Sky Survey (SDSS) spectra. A spectrophotometric distance estimate of 8.0+/-1.6 pc places SDSS J141624.08+134826.7 among the six closest known L dwarfs. SDSS 1416+13 was overlooked in infrared color-based searches because of its unusually blue J-K_S color, which also identifies it as the nearest member of the blue L dwarf subclass. We present additional infrared and optical spectroscopy from the IRTF/SpeX and Magellan/MagE spectrographs and determine UVW motions that indicate thin disk k…
We present a sample of 74,216 M and L dwarfs constructed from two existing catalogs of cool dwarfs spectroscopically identified in the Sloan Digital Sky Survey (SDSS). We cross-matched the SDSS catalog with Gaia DR2 to obtain parallaxes and proper motions and modified the quality cuts suggested by the Gaia Collaboration to make them suitable for late-M and L dwarfs. We also provide relations between Gaia colors and absolute magnitudes with spectral type and conclude that (G-RP) has the tightest relation to spectral type for M and L dwarfs. In addition, we study magnetic activity as a function …
AIMS: We aim to evaluate the near-infrared colors of brown dwarfs as observed with four major infrared imaging space observatories: the Hubble Space Telescope (HST), the James Webb Space Telescope (JWST), the Euclid mission, and the WFIRST telescope. METHODS: We used the SPLAT SPEX/ISPEX spectroscopic library to map out the colors of the M-, L-, and T-type dwarfs. We have identified which color-color combination is optimal for identifying broad type and which single color is optimal to then identify the subtype (e.g., T0-9). We evaluated each observatory separately as well as the narrow-field …
We present here medium resolution (λ/Δλ\sim1200) H- and K-band spectra of M type dwarf stars covering the wavelength range 1.50 - 1.80 μm and 1.95 - 2.45 μm. The sample includes 53 dwarf stars (M0V-M7V) from new observations using the TIFR Near-Infrared Spectrometer and Imager (TIRSPEC) instrument on the 2-m Himalayan Chandra Telescope (HCT). Using interferometrically-measured effective temperature (T_{eff}), radius and luminosity of nearby bright calibrator stars, we have created new empirical relationships among those fundamental parameters and spectral indices. The equivalent widths of H-ba…
We present the final results from a targeted search for brown dwarfs with unusual near-infrared colors. From a positional cross-match of SDSS, 2MASS and WISE, we have identified 144 candidate peculiar L and T dwarfs. Spectroscopy confirms that 20 of the objects are peculiar or are candidate binaries. Nine of the 420 objects in our sample are young ($\lesssim$200 Myr; 2.1%) and another 8 (1.9%) are unusually red with no signatures of youth. With a spectroscopic $J-K_s$ color of 2.58 $\pm$ 0.11 mag, one of the new objects, the L6 dwarf 2MASS J03530419+0418193, is among the reddest field dwarfs c…
Mid-infrared data, including Spitzer warm-IRAC [3.6] and [4.5] photometry, is critical for understanding the cold population of brown dwarfs now being found, objects which have more in common with planets than stars. As effective temperature (T_eff) drops from 800 K to 400 K, the fraction of flux emitted beyond 3 microns increases rapidly, from about 40% to >75%. This rapid increase makes a color like H-[4.5] a very sensitive temperature indicator, and it can be combined with a gravity- and metallicity-sensitive color like H-K to constrain all three of these fundamental properties, which in tu…
We report and characterize a white-light superflare on a previously undiscovered M dwarf detected by the ASAS-SN survey. Employing various color-magnitude and color-spectral type relationships, we estimate several stellar parameters, including the quiescent V-band magnitude, from which we derive a flare amplitude of $ΔV \sim 10$. We determine an r-band absolute magnitude of $M_{r} = 11.4$, consistent with a mid-M dwarf, and an approximate distance to the source of $2.2$ kpc. Using classical-flare models, we infer a flare energy of $E_{V} \simeq (4.1\pm 2.2)\times 10^{36}$ ergs, making this one…
We examine the hypothesis that the red near-infrared colors of some L dwarfs could be explained by a "dust haze" of small particles in their upper atmospheres. This dust haze would exist in conjunction with the clouds found in dwarfs with more typical colors. We developed a model which uses Mie theory and the Hansen particle size distributions to reproduce the extinction due to the proposed dust haze. We apply our method to 23 young L dwarfs and 23 red field L dwarfs. We constrain the properties of the dust haze including particle size distribution and column density using Markov-Chain Monte C…
We present a multi-color, high-cadence photometric study of a distant dwarf nova KSP-OT-201611a discovered by the Korea Microlensing Telescope Network Supernova Program. From October 2016 to May 2017, two outbursts, which comprises a super/long outburst followed by a normal/short outburst separated by $\sim$91 days, were detected in the $BVI$ bands. The shapes and amplitudes of the outbursts reveal the nature of KSP-OT-201611a to be an SU UMa- or U Gem-type dwarf nova. Color variations of periodic humps in the super/long outburst possibly indicate that KSP-OT-201611a is an SU UMa-type dwarf no…
We analyze rapid-cadence, multiwavelength photometry of AR Scorpii from three observatories, covering five observing seasons. We measure the arrival times of the system's beat pulses and use them to compute an updated ephemeris. The white dwarf spin-down rate is estimated with an uncertainty of only 4%. These results confirm, beyond any doubt, that the white dwarf's spin period is increasing at the rate consistent with by that of Stiller et al. (2018). We study the evolution of the beat pulse's color index across the orbit. The color of the primary pulse maxima varies significantly across the …
We report the discovery and validation of two TESS exoplanets orbiting faint M dwarfs: TOI-4479b and TOI-2081b. We have jointly analyzed space (TESS mission) and ground based (MuSCAT2, MuSCAT3 and SINISTRO instruments) lightcurves using our multi-color photometry transit analysis pipeline. This allowed us to compute contamination limits for both candidates and validate them as planet-sized companions. We found TOI-4479b to be a sub-Neptune-sized planet ($R_{p}=2.82^{+0.65}_{-0.63}~\rm R_{\oplus}$) and TOI-2081b to be a super-Earth-sized planet ($R_{p}=2.04^{+0.50}_{-0.54}~\rm R_{\oplus}$). Fur…
