arXiv subjects

J. D. Hartman

Publications and source records attributed to J. D. Hartman.

At least 37 records · Page 2Linked to original sources

arXiv2018

HATS-71b: A giant planet transiting an M3 dwarf star in TESS Sector 1

We report the discovery of HATS-71b, a transiting gas giant planet on a P = 3.7955 day orbit around a G = 15.35 mag M3 dwarf star. HATS-71 is the coolest M dwarf star known to host a hot Jupiter. The loss of light during transits is 4.7%, more than any other confirmed transiting planet system. The planet was identified as a candidate by the ground-based HATSouth transit survey. It was confirmed using ground-based photometry, spectroscopy, and imaging, as well as space-based photometry from the NASA TESS mission (TIC 234523599). Combining all of these data, and utilizing Gaia DR2, we find that the planet has a radius of $1.080 \pm 0.016 R_J$ and mass of $0.45 \pm 0.24 M_J$ (95% confidence upper limit of $0.81 M_J$ ), while the star has a mass of $0.569 \pm^{0.042}_{0.069}\,M_\odot$ and a radius of $0.5161\pm^{0.0053}_{0.0099}\,R_\odot$. The Gaia DR2 data show that HATS-71 lies near the binary main sequence in the Hertzsprung-Russell diagram, suggesting that there may be an unresolved stellar binary companion. All of the available data is well fitted by a model in which there is a secondary star of mass $0.24 M_\odot$, although we caution that at present there is no direct spectroscopic or imaging evidence for such a companion. Even if there does exist such a stellar companion, the radius and mass of the planet would be only marginally different from the values we have calculated under the assumption that the star is single.

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arXiv2018

HATS-60b - HATS-69b: Ten Transiting Planets From HATSouth

We report the discovery of ten transiting extrasolar planets by the HATSouth survey. The planets range in mass from the Super-Neptune HATS-62b, with $M_{p} < 0.179 M_{J}$, to the Super-Jupiter HATS-66b, with $M_{p} = 5.33 M_{J}$, and in size from the Saturn HATS-69b, with $R_{p} = 0.94 R_{J}$, to the inflated Jupiter HATS-67b, with $R_{p} = 1.69 R_{J}$. The planets have orbital periods between 1.6092 days (HATS-67b) and 7.8180 days (HATS-61b). The hosts are dwarf stars with masses ranging from $0.89 M_{\odot}$ (HATS-69) to $1.56 M_{\odot}$ (HATS-64), and have apparent magnitudes between $V = 12.276 \pm 0.020$ mag (HATS-68) and $V = 14.095 \pm 0.030$ mag (HATS-66). The Super-Neptune HATS-62b is the least massive planet discovered to date with a radius larger than Jupiter. Based largely on the Gaia DR2 distances and broad-band photometry, we identify three systems (HATS-62, -64, and -65) as having possible unresolved binary star companions. We discuss in detail our methods for incorporating the Gaia DR2 observations into our modeling of the system parameters, and into our blend analysis procedures.

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arXiv2018

HATS-70b: A 13 Mjup brown dwarf transiting an A star

We report the discovery of HATS-70b, a transiting brown dwarf at the deuterium burning limit. HATS-70b has a mass of Mp=12.9 +1.8/-1.6 Mjup and a radius of Rp=1.384 +0.079/-0.074 Rjup, residing in a close-in orbit with a period of 1.89 days. The host star is a M*=1.78 +/- 0.12 Msun A star rotating at vsini=40.61 +0.32/-0.35 km/s, enabling us to characterize the spectroscopic transit of the brown dwarf via Doppler tomography. We find that HATS-70b, like other massive planets and brown dwarfs previously sampled, orbits in a low projected-obliquity orbit with lambda=8.9 +5.6/-4.5 deg. The low obliquities of these systems is surprising given all brown dwarf and massive planets with obliquities measured orbit stars hotter than the Kraft break. This trend is tentatively inconsistent with dynamically chaotic migration for systems with massive companions, though the stronger tidal influence of these companions makes it difficult to draw conclusions on the primordial obliquity distribution of this population. We also introduce a modeling scheme for planets around rapidly rotating stars, accounting for the influence of gravity darkening on the derived stellar and planetary parameters.

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arXiv2018

HATS-59b,c: A Transiting Hot Jupiter and a Cold Massive Giant Planet Around a Sun-Like Star

We report the first discovery of a multi-planetary system by the HATSouth network, HATS-59b,c, a planetary system with an inner transiting hot Jupiter and an outer cold massive giant planet, which was detected via radial velocity. The inner transiting planet, HATS-59b, is on an eccentric orbit with $e = 0.129\pm0.049$, orbiting a $V=13.951\pm0.030$ mag solar-like star ($M_* = 1.038\pm0.039 M_{\odot}$, and $R_* = 1.036\pm0.067 R_{\odot}$) with a period of $5.416077\pm0.000017$ days. The outer companion, HATS-59c is on a circular orbit with $ m \sin i = 12.8\pm1.1 M_\mathrm{J}$, and a period of $1422\pm14$ days. The inner planet has a mass of $0.806\pm0.069 M_\mathrm{J}$ and a radius of $1.126\pm0.077 M_\mathrm{J}$, yielding a density of $0.70\pm0.16 {\rm g\,cm^{-3}}$. Unlike most of the planetary systems that include only a single hot Jupiter, HATS-59b,c includes, in addition to the transiting hot Jupiter, a massive outer companion. The architecture of this system is valuable for understanding planet migration.

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arXiv2018

HATS-39b, HATS-40b, HATS-41b, and HATS-42b: Three Inflated Hot Jupiters and a Super-Jupiter Transiting F Stars

We report the discovery of four transiting hot Jupiters from the HATSouth survey: HATS-39b, HATS-40b, HATS41b and HATS-42b. These discoveries add to the growing number of transiting planets orbiting moderately bright (12.5 < V < 13.7) F dwarf stars on short (2-5 day) periods. The planets have similar radii, ranging from 1.33(+0.29/-0.20) R_J for HATS-41b to 1.58(+0.16/-0.12) R_J for HATS-40b. Their masses and bulk densities, however, span more than an order of magnitude. HATS-39b has a mass of 0.63 +/- 0.13 M_J, and an inflated radius of 1.57 +/- 0.12 R_J, making it a good target for future transmission spectroscopic studies. HATS-41b is a very massive 9.7 +/- 1.6 M_J planet and one of only a few hot Jupiters found to date with a mass over 5 M_J. This planet orbits the highest metallicity star ([Fe/H] = 0.470 +/- 0.010) known to host a transiting planet and is also likely on an eccentric orbit. The high mass, coupled with a relatively young age (1.34 +0.31/-0.51 Gyr) for the host star, are factors that may explain why this planet's orbit has not yet circularised.

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arXiv2018

HAT-TR-318-007: a double-lined M-dwarf binary with total secondary eclipses discovered by HATNet and observed by K2

We report the discovery by the HATNet survey of HAT-TR-318-007, a $P = 3.34395390\pm0.00000020$ d period detached double-lined M-dwarf binary with total secondary eclipses. We combine radial velocity (RV) measurements from TRES/FLWO 1.5 m, and time-series photometry from HATNet, FLWO 1.2 m, BOS 0.8 m and NASA K2 Campaign 5, to determine the masses and radii of the component stars: $M_{A} = 0.448\pm0.011$ $M_{\odot}$, $M_{B} = 0.2721^{+0.0041}_{-0.0042}$ $M_{\odot}$, $R_{A} = 0.4548^{+0.0035}_{-0.0036}$ $R_{\odot}$, and $R_{B} = 0.2913^{+0.0023}_{-0.0024}$ $R_{\odot}$. We obtained a FIRE/Magellan near-infrared spectrum of the primary star during a total secondary eclipse, and use this to obtain disentangled spectra of both components. We determine spectral types of ST$_{A} = {\rm M}3.71\pm0.69$ and ST$_{B} = {\rm M}5.01\pm0.73$, and effective temperatures of T$_{\rm eff,A} = 3190\pm110$ K and T$_{\rm eff,B} = 3100\pm110$ K, for the primary and secondary star, respectively. We also measure a metallicity of [Fe/H]$=+0.298\pm0.080$ for the system. We find that the system has a small, but significant, non-zero eccentricity of $0.0136\pm0.0026$. The K2 light curve shows a coherent variation at a period of $3.41315^{+0.00030}_{-0.00032}$ d, which is slightly longer than the orbital period, and which we demonstrate comes from the primary star. We interpret this as the rotation period of the primary. We perform a quantitative comparison between the Dartmouth stellar evolution models and the seven systems, including HAT-TR-318-007, that contain M dwarfs with $0.2 M_{\odot} < M < 0.5 M_{\odot}$, have metallicity measurements, and have masses and radii determined to better than 5% precision. Discrepancies between the predicted and observed masses and radii are found for three of the systems.

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arXiv2017

HATS-50b through HATS-53b: four transiting hot Jupiters orbiting G-type stars discovered by the HATSouth survey

We report the discovery of four close-in transiting exoplanets, HATS-50 through HATS-53, discovered using the HATSouth three-continent network of homogeneous and automated telescopes. These new exoplanets belong to the class of hot Jupiters and orbit G-type dwarf stars, with brightness in the range V=12.5-14.0 mag. While HATS-53 has many physical characteristics similar to the Sun, the other three stars appear to be metal rich, larger and more massive. Three of the new exoplanets, namely HATS-50, HATS-51 and HATS-53, have low density and similar orbital period. Instead, HATS-52 is more dense and has a shorter orbital period. It also receives an intensive radiation from its parent star and, consequently, presents a high equilibrium temperature. HATS-50 shows a marginal additional transit feature consistent with an ultra-short period hot super Neptune, which will be able to be confirmed with TESS photometry.

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arXiv2017

HATS-43b, HATS-44b, HATS-45b, and HATS-46b: Four Short Period Transiting Giant Planets in the Neptune-Jupiter Mass Range

We report the discovery of four short period extrasolar planets transiting moderately bright stars from photometric measurements of the HATSouth network coupled to additional spectroscopic and photometric follow-up observations. While the planet masses range from 0.26 to 0.90 M$_J$, the radii are all approximately a Jupiter radii, resulting in a wide range of bulk densities. The orbital period of the planets range from 2.7d to 4.7d, with HATS-43b having an orbit that appears to be marginally non-circular (e= 0.173$\pm$0.089). HATS-44 is notable for a high metallicity ([Fe/H]= 0.320$\pm$0.071). The host stars spectral types range from late F to early K, and all of them are moderately bright (13.3<V<14.4), allowing the execution of future detailed follow-up observations. HATS-43b and HATS-46b, with expected transmission signals of 2350 ppm and 1500 ppm, respectively, are particularly well suited targets for atmospheric characterisation via transmission spectroscopy.

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arXiv2017

HATS-36b and 24 other transiting/eclipsing systems from the HATSouth - K2 Campaign 7 program

We report on the result of a campaign to monitor 25 HATSouth candidates using the K2 space telescope during Campaign 7 of the K2 mission. We discover HATS-36b (EPIC 215969174b), a hot Jupiter with a mass of 2.79$\pm$0.40 M$_J$ and a radius of 1.263$\pm$0.045 R$_J$ which transits a solar-type G0V star (V=14.386) in a 4.1752d period. We also refine the properties of three previously discovered HATSouth transiting planets (HATS-9b, HATS-11b, and HATS-12b) and search the K2 data for TTVs and additional transiting planets in these systems. In addition we also report on a further three systems that remain as Jupiter-radius transiting exoplanet candidates. These candidates do not have determined masses, however pass all of our other vetting observations. Finally we report on the 18 candidates which we are now able to classify as eclipsing binary or blended eclipsing binary systems based on a combination of the HATSouth data, the K2 data, and follow-up ground-based photometry and spectroscopy. These range in periods from 0.7 days to 16.7 days, and down to 1.5 mmag in eclipse depths. Our results show the power of combining ground-based imaging and spectroscopy with higher precision space-based photometry, and serve as an illustration as to what will be possible when combining ground-based observations with TESS data.

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arXiv2017

HAT-P-67b: An Extremely Low Density Saturn Transiting an F-Subgiant Confirmed via Doppler Tomography

We report the discovery of HAT-P-67b, a hot-Saturn transiting a rapidly rotating F-subgiant. HAT-P-67b has a radius of Rp = 2.085 -0.071/+0.096 RJ,, orbiting a M* = 1.642 -0.072/+0.155 Msun, R* = 2.546 -0.084/+0.099 Rsun host star in a ~4.81-day period orbit. We place an upper limit on the mass of the planet via radial velocity measurements to be Mp < 0.59 MJ, and lower limit of > 0.056 MJ by limitations on Roche lobe overflow. Despite being a subgiant, the host star still exhibits relatively rapid rotation, with a projected rotational velocity of v sin I* = 35.8 +/- 1.1 km/s, making it difficult to precisely determine the mass of the planet using radial velocities. We validated HAT-P-67b via two Doppler tomographic detections of the planetary transit, which eliminated potential eclipsing binary blend scenarios. The Doppler tomographic observations also confirmed that HAT-P-67b has an orbit that is aligned to within 12 degrees, in projection, with the spin of its host star. HAT-P-67b receives strong UV irradiation, and is amongst the one of the lowest density planets known, making it a good candidate for future UV transit observations to search for an extended hydrogen exosphere.

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arXiv2017

Image Subtraction Reduction of Open Clusters M35 & NGC 2158 In The K2 Campaign-0 Super-Stamp

Observations were made of the open clusters M35 and NGC 2158 during the initial K2 campaign (C0). Reducing these data to high-precision photometric time-series is challenging due to the wide point spread function (PSF) and the blending of stellar light in such dense regions. We developed an image-subtraction-based K2 reduction pipeline that is applicable to both crowded and sparse stellar fields. We applied our pipeline to the data-rich C0 K2 super-stamp, containing the two open clusters, as well as to the neighboring postage stamps. In this paper, we present our image subtraction reduction pipeline and demonstrate that this technique achieves ultra-high photometric precision for sources in the C0 super-stamp. We extract the raw light curves of 3960 stars taken from the UCAC4 and EPIC catalogs and de-trend them for systematic effects. We compare our photometric results with the prior reductions published in the literature. For detrended, TFA-corrected sources in the 12--12.25 $\rm K_{p}$ magnitude range, we achieve a best 6.5 hour window running rms of 35 ppm falling to 100 ppm for fainter stars in the 14--14.25 $ \rm K_{p}$ magnitude range. For stars with $\rm K_{p}> 14$, our detrended and 6.5 hour binned light curves achieve the highest photometric precision. Moreover, all our TFA-corrected sources have higher precision on all time scales investigated. This work represents the first published image subtraction analysis of a K2 super-stamp. This method will be particularly useful for analyzing the Galactic bulge observations carried out during K2 campaign 9. The raw light curves and the final results of our detrending processes are publicly available at \url{http://k2.hatsurveys.org/archive/}.

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arXiv2016

HATS-31b Through HATS-35b: Five Transiting Hot Jupiters Discovered by the HATSouth Survey

We report the discovery of five new transiting hot Jupiter planets discovered by the HATSouth survey: HATS-31b through HATS-35b. These planets orbit moderately bright stars with V magnitudes within the range 11.9-14.4mag while the planets span a range of masses 0.88-1.22MJ, and have somewhat inflated radii between 1.23-1.64RJ.These planets can be classified as typical hot Jupiters, with HATS-31b and HATS-35b being moderately inflated gas giant planets with radii of $1.64 \pm 0.22$ RJ and 1.464+0.069-0.044RJ, respectively, that can be used to constrain inflation mechanisms. All five systems present a higher Bayesian evidence for a fixed circular orbit model than for an eccentric orbit. The orbital periods range from $1.8209993 \pm 0.0000016$ day for HATS-35b) to $3.377960 \pm 0.000012$ day for HATS-31b. Additionally, HATS-35b orbits a relatively young F star with an age of $2.13 \pm 0.51$ Gyr. We discuss the analysis to derive the properties of these systems and compare them in the context of the sample of well characterized transiting hot Jupiters known to date.

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arXiv2016

HATS-19b, HATS-20b, HATS-21b: Three Transiting Hot-Saturns Discovered by the HATSouth Survey

We report the discovery by the HATSouth exoplanet survey of three hot-Saturn transiting exoplanets: HATS-19b, HATS-20b, and HATS-21b. The planet host HATS-19 is a slightly evolved V = 13.0 G0 star with [Fe/H] = 0.240, a mass of 1.303 Msun, and a radius of 1.75 Rsun. HATS-19b is in an eccentric orbit (e = 0.30) around this star with an orbital period of 4.5697 days and has a mass of 0.427 Mjup and a highly inflated radius of 1.66 Rjup. The planet HATS-20b has a Saturn-like mass and radius of 0.273 Mjup and 0.776 Rjup respectively. It orbits the V = 13.8 G9V star HATS-20 (Ms = 0.910 Msun; Rs = 0.892 Rsun) with a period of 3.7993 days. Finally, HATS-21 is a V = 12.2 G4V star with [Fe/H] = 0.300, a mass of 1.080 Msun, and a radius of 1.021 Rsun. Its accompanying planet HATS-21b has a 3.5544-day orbital period, a mass of 0.332 Mjup, and a moderately inflated radius of 1.123 Rjup. With the addition of these three very different planets to the growing sample of hot-Saturns, we re-examine the relations between the observed giant planet radii, stellar irradiation, and host metallicity. We find a significant positive correlation between planet equilibrium temperature and radius, and a weak negative correlation between host metallicity and radius. To assess the relative influence of various physical parameters on observed planet radii, we train and fit models using Random Forest regression. We find that for hot-Saturns (0.1 < Mp < 0.5 Mjup), the planetary mass and equilibrium temperature play dominant roles in determining radii. For hot-Jupiters (0.5 < Mp < 2.0 Mjup), the most important parameter is equilibrium temperature alone. Finally, for irradiated higher-mass planets (Mp > 2.0 Mjup), we find that equilibrium temperature dominates in influence, with smaller contributions from planet mass and host metallicity.

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arXiv2016

HAT-P-47b AND HAT-P-48b: Two Low Density Sub-Saturn-Mass Transiting Planets on the Edge of the Period--Mass Desert

We report the discovery of two new transiting extrasolar planets orbiting moderately bright (V = 10.7 and 12.2 mag) F stars (masses of 1.39 Msun and 1.10 Msun, respectively). The planets have periods of P = 4.7322 d and 4.4087 d, and masses of 0.21 MJ and 0.17 MJ which are almost half-way between those of Neptune and Saturn. With radii of 1.31 RJ and 1.13 RJ, these very low density planets are the two lowest mass planets with radii in excess that of Jupiter. Comparing with other recent planet discoveries, we find that sub-Saturns (0.18MJ < Mp < 0.3MJ) and super-Neptunes (0.05MJ < Mp < 0.18MJ) exhibit a wide range of radii, and their radii exhibit a weaker correlation with irradiation than higher mass planets. The two planets are both suitable for measuring the Rossiter-McLaughlin effect and for atmospheric characterization. Measuring the former effect would allow an interesting test of the theory that star-planet tidal interactions are responsible for the tendency of close-in giant planets around convective envelope stars to be on low obliquity orbits. Both planets fall on the edge of the short period Neptunian desert in the semi-major axis-mass plane.

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arXiv2016

HATS-25b through HATS-30b: A Half-dozen New Inflated Transiting Hot Jupiters from the HATSouth Survey

We report six new inflated hot Jupiters (HATS-25b through HATS-30b) discovered using the HATSouth global network of automated telescopes. The planets orbit stars with $V$ magnitudes in the range $\sim 12-14$ and have masses in the largely populated $0.5M_J-0.7M_J$ region of parameter space but span a wide variety of radii, from $1.17R_J$ to $1.75 R_J$. HATS-25b, HATS-28b, HATS-29b and HATS-30b are typical inflated hot Jupiters ($R_p = 1.17-1.26R_J$) orbiting G-type stars in short period ($P=3.2-4.6$ days) orbits. However, HATS-26b ($R_p = 1.75R_J$, $P = 3.3024$ days) and HATS-27b ($R_p=1.50R_J$, $P=4.6370$ days) stand out as highly inflated planets orbiting slightly evolved F stars just after and in the turn-off points, respectively, which are among the least dense hot Jupiters, with densities of $0.153$ g cm$^{-3}$ and $0.180$ g cm$^{-3}$, respectively. All the presented exoplanets but HATS-27b are good targets for future atmospheric characterization studies, while HATS-27b is a prime target for Rossiter-McLaughlin monitoring in order to determine its spin-orbit alignment given the brightness ($V = 12.8$) and stellar rotational velocity ($v \sin i \approx 9.3$ km/s) of the host star. These discoveries significantly increase the number of inflated hot Jupiters known, contributing to our understanding of the mechanism(s) responsible for hot Jupiter inflation.

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arXiv2016

HATS-11b and HATS-12b: Two transiting Hot Jupiters orbiting sub-solar metallicity stars selected for the K2 Campaign 7

We report the discovery of two transiting extrasolar planets from the HATSouth survey. HATS-11, a V=14.1 G0-star shows a periodic 12.9 mmag dip in its light curve every 3.6192 days and a radial velocity variation consistent with a Keplerian orbit. HATS-11 has a mass of 1.000 $\pm$ 0.060 M$_{\odot}$, a radius of 1.444 $\pm$ 0.057 M$_{\odot}$ and an effective temperature of 6060 $\pm$ 150 K, while its companion is a 0.85 $\pm$ 0.12 M$_J$, 1.510 $\pm$ 0.078 R$_J$ planet in a circular orbit. HATS-12 shows a periodic 5.1 mmag flux decrease every 3.1428 days and Keplerian RV variations around a V=12.8 F-star. HATS-12 has a mass of 1.489 $\pm$ 0.071 M$_{\odot}$, a radius of 2.21 $\pm$ 0.21 R$_{\odot}$, and an effective temperature of 6408 $\pm$ 75 K. For HATS-12, our measurements indicate that this is a 2.38 $\pm$ 0.11 M$_J$, 1.35 $\pm$ 0.17 R$_J$ planet in a circular orbit. Both host stars show sub-solar metallicity of -0.390 $\pm$ 0.060 dex and -0.100 $\pm$ 0.040 dex, respectively and are (slightly) evolved stars. In fact, HATS-11 is amongst the most metal-poor and, HATS-12 is amongst the most evolved stars hosting a hot Jupiter planet. Importantly, HATS-11 and HATS-12 have been observed in long cadence by Kepler as part of K2 campaign 7 (EPIC216414930 and EPIC218131080 respectively).

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arXiv2015

HATS-15 b and HATS-16 b: Two massive planets transiting old G dwarf stars

We report the discovery of HATS-15 b and HATS-16 b, two massive transiting extrasolar planets orbiting evolved ($\sim 10$ Gyr) main-sequence stars. The planet HATS-15 b, which is hosted by a G9V star ($V=14.8$ mag), is a hot Jupiter with mass of $2.17\pm0.15\, M_{\mathrm{J}}$ and radius of $1.105\pm0.0.040\, R_{\mathrm{J}}$, and completes its orbit in nearly 1.7 days. HATS-16 b is a very massive hot Jupiter with mass of $3.27\pm0.19\, M_{\mathrm{J}}$ and radius of $1.30\pm0.15\, R_{\mathrm{J}}$; it orbits around its G3 V parent star ($V=13.8$ mag) in $\sim2.7$ days. HATS-16 is slightly active and shows a periodic photometric modulation, implying a rotational period of 12 days which is unexpectedly short given its isochronal age. This fast rotation might be the result of the tidal interaction between the star and its planet.

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arXiv2015

A high obliquity orbit for the hot-Jupiter HATS-14b transiting a 5400K star

We report a spin-orbit misalignment for the hot-Jupiter HATS-14b, measuring a projected orbital obliquity of |lambda|= 76 -5/+4 deg. HATS-14b orbits a high metallicity, 5400 K G dwarf in a relatively short period orbit of 2.8 days. This obliquity was measured via the Rossiter-McLaughlin effect, obtained with observations from Keck-HIRES. The velocities were extracted using a novel technique, optimised for low signal-to-noise spectra, achieving a high precision of 4 m/s point-to-point scatter. However, we caution that our uncertainties may be underestimated. Due to the low rotational velocity of the star, the detection significance is dependent on the vsini prior that is imposed in our modelling. Based on trends observed in the sample of hot Jupiters with obliquity measurements, it has been suggested that these planets modify the spin axes of their host stars, with an efficiency that depends on the stellar type and orbital period of the system. In this framework, short-period planets around stars with surface convective envelopes, like HATS-14b, are expected to have orbits that are aligned with the spin axes of their host stars. HATS-14b, however, is a significant outlier from this trend, challenging the effectiveness of the tidal realignment mechanism.

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