The detection of point sources in images is a fundamental operation in astrophysics, and is crucial for constraining population models of the underlying point sources or characterizing the background ...emission. Standard techniques fall short in the crowded-field limit, losing sensitivity to faint sources and failing to track their covariance with close neighbors. We construct a Bayesian framework to perform inference of faint or overlapping point sources. The method involves probabilistic cataloging, where samples are taken from the posterior probability distribution of catalogs consistent with an observed photon count map. In order to validate our method, we sample random catalogs of the gamma-ray sky in the direction of the North Galactic Pole (NGP) by binning the data in energy and point-spread function classes. Using three energy bins spanning 0.3-1, 1-3, and 3-10 GeV, we identify point sources inside a region around the NGP above our point-source inclusion limit of cm−2 s−1 sr−1 GeV−1 at the 1-3 GeV energy bin. Modeling the flux distribution as a power law, we infer the slope to be and estimate the contribution of point sources to the total emission as %. These uncertainties in the flux distribution are fully marginalized over the number as well as the spatial and spectral properties of the unresolved point sources. This marginalization allows a robust test of whether the apparently isotropic emission in an image is due to unresolved point sources or of truly diffuse origin.
Probabilistic cataloging (PCAT) outperforms traditional cataloging methods on single-band optical data in crowded fields. We extend our work to multiple bands, achieving greater sensitivity (∼0.4 ...mag) and greater speed (500×) compared to previous single-band results. We demonstrate the effectiveness of multiband PCAT on mock data, in terms of both recovering accurate posteriors in the catalog space and directly deblending sources. When applied to Sloan Digital Sky Survey (SDSS) observations of M2, taking Hubble Space Telescope data as truth, our joint fit on r- and i-band data goes ∼0.4 mag deeper than single-band probabilistic cataloging and has a false discovery rate less than 20% for F606W ≤ 20. Compared to DAOPHOT, the two-band SDSS catalog fit goes nearly 1.5 mag deeper using the same data and maintains a lower false discovery rate down to F606W ∼ 20.5. Given recent improvements in computational speed, multiband PCAT shows promise in application to large-scale surveys and is a plausible framework for joint analysis of multi-instrument observational data. https://github.com/RichardFeder/multiband_pcat.
NASA's Transiting Exoplanet Survey Satellite (TESS) presents us with an unprecedented volume of space-based photometric observations that must be analyzed in an efficient and unbiased manner. With at ...least ∼1,000,000 new light curves generated every month from full-frame images alone, automated planet candidate identification has become an attractive alternative to human vetting. Here we present a deep learning model capable of performing triage and vetting on TESS candidates. Our model is modified from an existing neural network designed to automatically classify Kepler candidates, and is the first neural network to be trained and tested on real TESS data. In triage mode, our model can distinguish transit-like signals (planet candidates and eclipsing binaries) from stellar variability and instrumental noise with an average precision (the weighted mean of precisions over all classification thresholds) of 97.0% and an accuracy of 97.4%. In vetting mode, the model is trained to identify only planet candidates with the help of newly added scientific domain knowledge, and achieves an average precision of 69.3% and an accuracy of 97.8%. We apply our model on new data from Sector 6, and present 288 new signals that received the highest scores in triage and vetting and were also identified as planet candidates by human vetters. We also provide a homogeneously classified set of TESS candidates suitable for future training.
Abstract
We present the early-time light curves of Type Ia supernovae (SNe Ia) observed in the first six sectors of Transiting Exoplanet Survey Satellite (TESS) data. Ten of these SNe were discovered ...by ASAS-SN, seven by ATLAS, six by ZTF, and one by Gaia. For nine of these objects with sufficient dynamic range (>3.0 mag from detection to peak), we fit power-law models and searched for signatures of companion stars. We found a diversity of early-time light-curve shapes, although most of our sources are consistent with fireball models where the flux increases as ∝
t
2
. Three SNe displayed a flatter rise with flux ∝
t
. We did not find any obvious evidence for additional structures, such as multiple power-law components, in the early rising light curves. For assumptions about the SN properties and the observer viewing angle (ejecta mass of 1.4
M
⊙
, expansion velocity of 10
4
km s
−1
, opacity of 0.2 cm
2
g
−1
, and viewing angle of 45°) and a further assumption that any companion stars would be in Roche lobe overflow, it is possible to place upper limits on the radii of any companion stars. Six of the nine SNe had complete coverage of the early-time light curves, and we placed upper limits on the radii of companion stars of ≲32
R
⊙
for these SNe, ≲20
R
⊙
for five of the six, and ≲4
R
⊙
for two of the six. The small sample size did not allow us to put limits on the occurrence rate of companion stars in the progenitors of SNe Ia. However, we expect that TESS observed enough SNe in its two-year primary mission (26 sectors) to either detect the signature of a large companion (
R
> 20
R
⊙
) or constrain the occurrence rate of such systems, at least for the fiducial SN properties adopted here. We also show that TESS is capable of detecting emission from a 1
R
⊙
companion for an SN Ia within 50 Mpc and has a reasonable chance of doing so after about six years.
We report the discovery of a warm sub-Saturn, TOI-257b (HD 19916b), based on data from NASA’s Transiting Exoplanet Survey Satellite (TESS). The transit signal was detected by TESS and confirmed to be ...of planetary origin based on radial velocity observations. An analysis of the TESS photometry, the MINERVA-Australis, FEROS, and HARPS radial velocities, and the asteroseismic data of the stellar oscillations reveals that TOI-257b has a mass of M(P) = 0.138 ± 0.023 M(J) (43.9 ± 7.3 Mꚛ), a radius of R(P) = 0.639 ± 0.013 R(J) (7.16 ± 0.15 Rꚛ), bulk density of 0.65 (+0.12,−0.11) (cgs), and period 18.38818 (+0.00085,−0.00084) days. TOI-257b orbits a bright (V = 7.612 mag) somewhat evolved late F-type star with M⁎ = 1.390 ± 0.046 M(sun), R⁎ = 1.888 ± 0.033 R(sun), T(eff) = 6075 ± 90 K, and 𝜈sin 𝑖 = 11.3 ± 0.5 km/s. Additionally, we find hints for a second non-transiting sub-Saturn mass planet on a ∼71 day orbit using the radial velocity data. This system joins the ranks of a small number of exoplanet host stars (∼100) that have been characterized with asteroseismology. Warm sub-Saturns are rare in the known sample of exoplanets, and thus the discovery of TOI-257b is important in the context of future work studying the formation and migration history of similar planetary systems.
Abstract
Planets around young stars trace the early evolution of planetary systems. We report the discovery and validation of two planetary systems with ages ≲300 Myr from observations by the ...Transiting Exoplanet Survey Satellite (TESS). The
Myr old G star TOI-251 hosts a
mini-Neptune with a
day period. The
Myr old K star TOI-942 hosts a system of inflated Neptune-sized planets, with TOI-942b orbiting in a period of
days with a radius of
and TOI-942c orbiting in a period of
days with a radius of
. Though we cannot place either host star into a known stellar association or cluster, we can estimate their ages via their photometric and spectroscopic properties. Both stars exhibit significant photometric variability due to spot modulation, with measured rotation periods of ∼3.5 days. These stars also exhibit significant chromospheric activity, with age estimates from the chromospheric calcium emission lines and X-ray fluxes matching that estimated from gyrochronology. Both stars also exhibit significant lithium absorption, similar in equivalent width to well-characterized young cluster members. TESS has the potential to deliver a population of young planet-bearing field stars, contributing significantly to tracing the properties of planets as a function of their age.
Phase-curve measurements provide a global view of the composition, thermal structure, and dynamics of exoplanet atmospheres. Although most of the dozens of phase-curve measurements made to date are ...of large, massive hot Jupiters, there is considerable interest in probing the atmospheres of the smaller planets that are the more typical endproduct of the planet formation process. One such planet that is favorable for these studies is the ultrahot Neptune LTT 9779b, a rare denizen of the Neptune desert. A companion paper presents the planet's secondary eclipses and dayside thermal emission spectrum; in this work we describe the planet's optical and infrared phase curves, characterized using a combination of Spitzer and Transiting Exoplanet Survey Satellite (TESS) photometry. We detect LTT 9779b's thermal phase variations at 4.5 m, finding a phase amplitude of 358 106 ppm and no significant phase offset, with a longitude of peak emission occurring −10° 21° east of the substellar point. Combined with our secondary eclipse observations, these phase-curve measurements imply a 4.5 m dayside brightness temperature of 1800 120 K, a nightside brightness temperature of 700 430 K (<1350 K at 2 confidence), and a day-night brightness temperature contrast of 1110 460 K. We compare our data to the predictions of 3D general circulation models calculated at multiple metallicity levels and to similar observations of hot Jupiters experiencing similar levels of stellar irradiation. Though not conclusive, our measurement of its small 4.5 m phase offset, the relatively large amplitude of the phase variation, and the qualitative differences between our target's dayside emission spectrum and those of hot Jupiters of similar temperatures all suggest a supersolar atmospheric metallicity for LTT 9779b, as might be expected given its size and mass. Finally, we measure the planet's transits at both 3.6 m and 4.5 m, providing a refined ephemeris (P = 0.79207022 0.00000069 days, T0 = 2458783.51636 0.00027, BJDTDB) that will enable efficient scheduling of future observations to further characterize the atmosphere of this intriguing planet.
We report the discovery of TOI-677b,first identified as a candidate in light curves obtained within Sectors 9 and 10 of the Transiting Exoplanet Survey Satellite(TESS)mission and confirmed with ...radial velocities. TOI-677b has a mass of M(p) = 1.236(+0.069,- 0.067) M(J), a radius of R(P)=1.170 ± 0.03 R(J), and orbits its bright host star (V = 9.8 mag) with an orbital period of 11.23660 ± 0.00011 d, on an eccentric orbit with e = 0.435 ± 0.024. The host star has a mass of M(*) = 1.181 ± 0.058 M(ʘ), a radius of R(*)= 1.28(+0.03,-0.03) R(ʘ), an age of 2.92 (+0.80,-0.73) Gyr and solar metallicity, properties consistent with a main-sequence late-F star with T(eff)=6295 ± 77K. We find evidence in the radial velocity measurements of a secondary long-term signal, which could be due to an outer companion. The TOI-677 b system is a well-suited target for Rossiter–Mclaughlin observations that can constrain migration mechanisms of close-in giant planets.
Cataloging is challenging in crowded fields because sources are extremely covariant with their neighbors and blending makes even the number of sources ambiguous. We present the first optical ...probabilistic catalog, cataloging a crowded (∼0.1 sources per pixel brighter than 22nd mag in F606W) Sloan Digital Sky Survey r-band image from M2. Probabilistic cataloging returns an ensemble of catalogs inferred from the image and thus can capture source-source covariance and deblending ambiguities. By comparing to a traditional catalog of the same image and a Hubble Space Telescope catalog of the same region, we show that our catalog ensemble better recovers sources from the image. It goes more than a magnitude deeper than the traditional catalog while having a lower false-discovery rate brighter than 20th mag. We also present an algorithm for reducing this catalog ensemble to a condensed catalog that is similar to a traditional catalog, except that it explicitly marginalizes over source-source covariances and nuisance parameters. We show that this condensed catalog has a similar completeness and false-discovery rate to the catalog ensemble. Future telescopes will be more sensitive, and thus more of their images will be crowded. Probabilistic cataloging performs better than existing software in crowded fields and so should be considered when creating photometric pipelines in the Large Synoptic Survey Telescope era.
Yıldızların önünden geçerken ürettikleri geçiş sinyali, ötegezegenleri keşfedebilmemizi ve nitelendirmemizi sağlayan en önemli gözlemlenebilirlerden biridir. Geçiş-Yapan Ötegezegen Tarama Uydusu ...(TESS) tarafından toplanan hassas ışık ölçüm verisi kullanarak, TESS İlginç Nesne çalışma grubu Kasım 2022 itibarıyla 6.000'i aşkın ötegezegen adayı tespit etmiştir. Bunlar içerisinde barınak yıldızı genç, yörünge mimarisi nadir ve çok-ötegezenli birçok sistem bulunmaktadır. Bu çeşitliliğin ötegezegen oluşum ve evrim süreçleri konusundaki algımızı ciddi şekilde güçlendirmesi beklenmektedir. Bilhassa TESS'in keşfettiği birçok küçük ötezegen JWST ve diğer uzay- ve yer-konuşlu büyük teleskoplar tarafından geçiş tayfı ölçümüne elverişlidir ve Neptün-altı ve kayasal ötegezegenlerin atmosfer niteliklerinin ortaya çıkarılmasına büyük bir katkıda bulunmaktadırlar.
The photometric signal produced when an exoplanet transits its host star is one of the most fundamental observables that allows us to discover and characterize exoplanets. Using the high-precision photometry from the Transiting Exoplanet Survey Satellite (TESS), the TESS Objects of Interest (TOI) working group has identified over 6,000 TOIs as of November 2022. Among these are many systems with young host stars, rare orbital architectures, and multiple planets. It is anticipated that this diversity will significantly strengthen our understanding of processes in planet formation and evolution. In particular, numerous small worlds discovered by TESS are amenable to transmission spectroscopy using JWST and other ground- and space-based large telescopes and play a major role in revealing the atmospheric properties of sub-Neptunes and terrestrial planets.
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