arXiv subjects

Eric G. Hintz

Publications and source records attributed to Eric G. Hintz.

11 recordsLinked to original sources

arXiv2026

The Orbital Eccentricity--Radius Distribution for Warm, Single Planets in TESS

We characterize the radius-dependent eccentricity distribution of 219 warm (P = 8--50 days) systems with only one transiting planetary candidate identified during Sectors 1-69 of the TESS mission. Using the ``photoeccentric effect'' in a hierarchical Bayesian framework, we first model the population using discrete planetary size bins (sub-Neptunes, sub-Saturns, and Jovians). We then develop a continuous mixture model with weights governed by a logistic sigmoid function of radius. We find that the warm-single population is best described by two components: a dominant low-eccentricity mode ( = 0.039-0.038+0.018) and a secondary dynamically excited mode ( = 0.466-0.068+0.067). The fraction of planets belonging to this high-eccentricity component increases strongly with planet radius, characterized by a transition at a break radius of R_br = 9.2-1.1+1.9 R_e. This trend places warm sub-Saturns predominantly on the same low-eccentricity track as sub-Neptunes. In contrast, warm Jovians (8--16 R_e) are frequently eccentric, with 65-12+13% of the population in the high eccentricity mode. Under the assumption of a two-component model, we see tentative evidence for a bimodal Jovian distribution at ~2.7 sigma. Finally, we identify a non-negligible tail of highly eccentric sub-Neptunes (1--4 R_e), which comprise 16.2-6.4+5.2% of the population, consistent with excitation by non-transiting external companions.

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arXiv2026

Observing a 542-day transiting giant with large TTVs: The 2025 transit of HIP 41378 f and new constraints on the outer system

Characterizing long-period transiting exoplanets is inherently challenging due to the rarity and long duration of transit events. Yet, these systems provide unique insights into planetary formation, migration, the detection of exomoons, and primordial atmospheres by occupying a sparsely populated region of the exoplanet parameter space. The complexity increases further for long-period planets near mean-motion resonances, where transit timing variations (TTVs) can reach amplitudes of several hours to days. We present a coordinated space- and ground-based observing campaign, using photometry from NEOSSat, multiple LCOGT sites, MuSCAT, MuSCAT3, Tierras and NGTS, to capture the 19-hour transit of the long-period giant exoplanet HIP 41378 f ($P$ = 542 d, $R$ = 9.5 $R_{\oplus}$) on 31 October 2025. Our transit analysis constrains the time of inferior conjunction to $T_{\mathrm{C}} = 2460980.888 \pm 0.029~\mathrm{BJD_{TDB}}$, occurring $\sim 7$ hours earlier than predicted from its linear ephemeris. This significant offset is consistent with the previously reported TTVs of HIP 41378 f, making it the longest-period exoplanet known to exhibit measurable TTVs. By combining this new precise measurement to the transit timings of the two outer planets in the system (HIP 41378 d and HIP 41378 e), we perform a dynamical modeling of the system, using the N-body integrator TRADES, refine the ephemeris of HIP 41378 f, and predict future transit events for all three outer transiting planets.

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arXiv2025

Near-IR CO and CN in classical Cepheids

We present medium resolution near-infrared spectral measurements of the carbon monoxide (CO) and the cyano radical (CN) features in 12 Galactic classical Cepheids. The pulsation periods of our sample range from 5.5 to 69 days, and the stars studied each had five or more near-IR spectral observations. The CO and CN measurements were used to probe CNO abundances of these stars, and elemental abundance values from the literature were used to identify the trends of [C/N] and [O/N] with CN and CO. To put these measurements in context, we performed stellar atmosphere fitting to obtain estimates of stellar parameters, with a primary focus on effective temperature. Our measurements and temperature estimates show that CN is significantly affected by dredge-up of processed material. We provide discussion as to the potential nature of the recently confirmed classical Cepheid, ET~Vul, and connect our near-infrared CO measurements to the mid-infrared period-colour-metallicity relation.

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arXiv2025

The TESS Grand Unified Hot Jupiter Survey. III. Thirty More Giant Planets

We present the discovery of 30 transiting giant planets that were initially detected using data from NASA's Transiting Exoplanet Survey Satellite (TESS) mission. These new planets orbit relatively bright ($G \leq 12.5$) FGK host stars with orbital periods between 1.6 and 8.2 days, and have radii between 0.9 and 1.7 Jupiter radii. We performed follow-up ground-based photometry, high angular-resolution imaging, high-resolution spectroscopy and radial velocity monitoring for each of these objects to confirm that they are planets and determine their masses and other system parameters. The planets' masses span more than an order of magnitude ($0.17\,M_J < M_p < 3.3\,M_J$). For two planets, TOI-3593 b and TOI-4961 b, we measured significant non-zero eccentricities of $0.11^{+0.05}_{-0.03}$ and $0.18^{+0.04}_{-0.05}$ respectively, while for the other planets, the data typically provide a 1-$σ$ upper bound of 0.15 on the eccentricity. These discoveries represent a major step toward assembling a complete, magnitude-limited sample of transiting hot Jupiters around FGK stars.

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arXiv2024

Changing CO Bands in Near-IR Spectra of CP Cephei

We present time-series near-infrared spectra for the classical Cepheid, CP Cephei, from the Astrophysical Research Consortium 3.5-m telescope and near-infrared spectrograph, TripleSpec, at Apache Point Observatory, NM, USA. Spectral observations were made at nine points through the minimum and partway up the ascending portion of the optical light curve for the star. Carbon monoxide (CO) was detected in absorption in the 2.3-$μ$m region for each observation. We measured the strength of CO absorption using the 2-0 band head in the feature for each observation and confirm that the CO varies with pulsation. We show that these measurements follow the $(J-K)$ colour curve, confirming that temperature drives the destruction of CO. By obtaining convolved filter magnitudes from the spectral data we found that the effect of the CO feature on $K$ magnitudes is small, unlike the CO feature in the mid-infrared at 4.5-$μ$m. The dissociation of CO in the near-infrared spectra tracks with the effect seen in the mid-infrared photometric measurements of a similar Galactic Cepheid. Confirmation of the varying CO feature illustrates the need for further investigations into the related mid-infrared period-colour-metallicity relation in order to address the impact of Cepheid metallicities on the Hubble tension.

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arXiv2023

Another Shipment of Six Short-Period Giant Planets from TESS

We present the discovery and characterization of six short-period, transiting giant planets from NASA's Transiting Exoplanet Survey Satellite (TESS) -- TOI-1811 (TIC 376524552), TOI-2025 (TIC 394050135), TOI-2145 (TIC 88992642), TOI-2152 (TIC 395393265), TOI-2154 (TIC 428787891), & TOI-2497 (TIC 97568467). All six planets orbit bright host stars (8.9 <G< 11.8, 7.7 <K< 10.1). Using a combination of time-series photometric and spectroscopic follow-up observations from the TESS Follow-up Observing Program (TFOP) Working Group, we have determined that the planets are Jovian-sized (R$_{P}$ = 1.00-1.45 R$_{J}$), have masses ranging from 0.92 to 5.35 M$_{J}$, and orbit F, G, and K stars (4753 $<$ T$_{eff}$ $<$ 7360 K). We detect a significant orbital eccentricity for the three longest-period systems in our sample: TOI-2025 b (P = 8.872 days, $e$ = $0.220\pm0.053$), TOI-2145 b (P = 10.261 days, $e$ = $0.182^{+0.039}_{-0.049}$), and TOI-2497 b (P = 10.656 days, $e$ = $0.196^{+0.059}_{-0.053}$). TOI-2145 b and TOI-2497 b both orbit subgiant host stars (3.8 $<$ $\log$ g $<$4.0), but these planets show no sign of inflation despite very high levels of irradiation. The lack of inflation may be explained by the high mass of the planets; $5.35^{+0.32}_{-0.35}$ M$_{\rm J}$ (TOI-2145 b) and $5.21\pm0.52$ M$_{\rm J}$ (TOI-2497 b). These six new discoveries contribute to the larger community effort to use {\it TESS} to create a magnitude-complete, self-consistent sample of giant planets with well-determined parameters for future detailed studies.

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arXiv2021

TIC 172900988: A Transiting Circumbinary Planet Detected in One Sector of TESS Data

We report the first discovery of a transiting circumbinary planet detected from a single sector of TESS data. During Sector 21, the planet TIC 172900988b transited the primary star and then 5 days later it transited the secondary star. The binary is itself eclipsing, with a period of P = 19.7 days and an eccentricity of e = 0.45. Archival data from ASAS-SN, Evryscope, KELT, and SuperWASP reveal a prominent apsidal motion of the binary orbit, caused by the dynamical interactions between the binary and the planet. A comprehensive photodynamical analysis of the TESS, archival and follow-up data yields stellar masses and radii of M1 = 1.2384 +/- 0.0007 MSun and R1 = 1.3827 +/- 0.0016 RSun for the primary and M2 = 1.2019 +/- 0.0007 MSun and R2 = 1.3124 +/- 0.0012 RSun for the secondary. The radius of the planet is R3 = 11.25 +/- 0.44 REarth (1.004 +/- 0.039 RJup). The planet's mass and orbital properties are not uniquely determined - there are six solutions with nearly equal likelihood. Specifically, we find that the planet's mass is in the range of 824 < M3 < 981 MEarth (2.65 < M3 < 3.09 MJup), its orbital period could be 188.8, 190.4, 194.0, 199.0, 200.4, or 204.1 days, and the eccentricity is between 0.02 and 0.09. At a V = 10.141 mag, the system is accessible for high-resolution spectroscopic observations, e.g. Rossiter-McLaughlin effect and transit spectroscopy.

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arXiv2018

The KELT Follow-Up Network and Transit False Positive Catalog: Pre-vetted False Positives for TESS

The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey for transiting planets orbiting bright stars for over ten years. The KELT images have a pixel scale of ~23"/pixel---very similar to that of NASA's Transiting Exoplanet Survey Satellite (TESS)---as well as a large point spread function, and the KELT reduction pipeline uses a weighted photometric aperture with radius 3'. At this angular scale, multiple stars are typically blended in the photometric apertures. In order to identify false positives and confirm transiting exoplanets, we have assembled a follow-up network (KELT-FUN) to conduct imaging with higher spatial resolution, cadence, and photometric precision than the KELT telescopes, as well as spectroscopic observations of the candidate host stars. The KELT-FUN team has followed-up over 1,600 planet candidates since 2011, resulting in more than 20 planet discoveries. Excluding ~450 false alarms of non-astrophysical origin (i.e., instrumental noise or systematics), we present an all-sky catalog of the 1,128 bright stars (6<V<10) that show transit-like features in the KELT light curves, but which were subsequently determined to be astrophysical false positives (FPs) after photometric and/or spectroscopic follow-up observations. The KELT-FUN team continues to pursue KELT and other planet candidates and will eventually follow up certain classes of TESS candidates. The KELT FP catalog will help minimize the duplication of follow-up observations by current and future transit surveys such as TESS.

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arXiv2018

KELT-21b: A Hot Jupiter Transiting the Rapidly-Rotating Metal-Poor Late-A Primary of a Likely Hierarchical Triple System

We present the discovery of KELT-21b, a hot Jupiter transiting the $V=10.5$ A8V star HD 332124. The planet has an orbital period of $P=3.6127647\pm0.0000033$ days and a radius of $1.586_{-0.040}^{+0.039}$ $R_J$. We set an upper limit on the planetary mass of $M_P<3.91$ $M_J$ at $3σ$ confidence. We confirmed the planetary nature of the transiting companion using this mass limit and Doppler tomographic observations to verify that the companion transits HD 332124. These data also demonstrate that the planetary orbit is well-aligned with the stellar spin, with a sky-projected spin-orbit misalignment of $λ=-5.6_{-1.9}^{+1.7 \circ}$. The star has $T_{\mathrm{eff}}=7598_{-84}^{+81}$ K, $M_*=1.458_{-0.028}^{+0.029}$ $M_{\odot}$, $R_*=1.638\pm0.034$ $R_{\odot}$, and $v\sin I_*=146$ km s$^{-1}$, the highest projected rotation velocity of any star known to host a transiting hot Jupiter. The star also appears to be somewhat metal-poor and $α$-enhanced, with [Fe/H]$=-0.405_{-0.033}^{+0.032}$ and [$α$/Fe]$=0.145 \pm 0.053$; these abundances are unusual, but not extraordinary, for a young star with thin-disk kinematics like KELT-21. High-resolution imaging observations revealed the presence of a pair of stellar companions to KELT-21, located at a separation of 1.2" and with a combined contrast of $ΔK_S=6.39 \pm 0.06$ with respect to the primary. Although these companions are most likely physically associated with KELT-21, we cannot confirm this with our current data. If associated, the candidate companions KELT-21 B and C would each have masses of $\sim0.12$ $M_{\odot}$, a projected mutual separation of $\sim20$ AU, and a projected separation of $\sim500$ AU from KELT-21. KELT-21b may be one of only a handful of known transiting planets in hierarchical triple stellar systems.

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arXiv2017

A Pulsational Time-evolution Study for the $δ$ Scuti Star AN Lyncis

This paper presents a large amount of observations for the $δ$ Scuti star AN Lyncis carried out in 2001--2012. The extensive observations include two tri-continent campaigns coordinated in 2002 and 2011, respectively, and several single-site contributions throughout the period. The data in total have more than 104100 raw CCD frames and photoelectric records, which consist of 165 nights (about 816 hours) spanning over 3778 days. The final reduced light curves have more than 26500 data points (including those 3462 unpublished BYU data), from which we determined 306 new timings of maximum light. A time-dependent behaviour study based on all available data indicates cyclic amplitude variability as well as period change [for the main periodicity]. Orbital sinusoid fittings to $(O-C)$ residuals and pulsation amplitudes may account for their variations being caused by the light-time effect of AN Lyn in a binary system. The orbital period is about 26--30 years. Current results support the binarity of AN Lyn, first suspected by Zhou (2002). We further show the detailed time evolution structure of the pulsation of AN Lyn as function of both time and period through wavelet analyses.

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arXiv2016

The Effect of Nearby Voids on Galaxy Number Counts

The size, shape and degree of emptiness of void interiors sheds light on the details of galaxy formation. A particularly interesting question is whether void interiors are completely empty or contain a dwarf population. However the nearby voids that are most conducive for dwarf searches have large angular diameters, on the order of a steradian, making it difficult to redshift-map a statistically significant portion of their volume to the magnitude limit of dwarf galaxies. As part of addressing this problem, we investigate here the usefulness of number counts in establishing the best locations to search inside nearby (d < 300 Mpc) galaxy voids, utilizing Wolf plots of log(n < m) vs. m as the basic diagnostic. To illustrate expected signatures, we consider the signature of three void profiles, "cut out", "built up", and "universal profile" carved into Monte-Carlo Schechter function models. We then investigate the signatures of voids in the Millennium Run dark matter simulation and the Sloan Digital Sky Survey. We find in all of these the evidence for cut-out and built-up voids is most discernible when the void diameter is similar to the distance to its center. However the density distribution of the universal profile that is characteristic of actual voids is essentially undetectable at any distance. A useful corollary of this finding is that galaxy counts are a reliable measure of survey completeness and stellar contamination even when sampling through significant voids.

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