skip to main content

Attention:

The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 11:00 PM ET on Thursday, June 13 until 2:00 AM ET on Friday, June 14 due to maintenance. We apologize for the inconvenience.


Search for: All records

Creators/Authors contains: "Triaud, Amaury H. M. J."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Abstract

    We present high-precision radial velocity observations of Gaia BH1, the nearest known black hole (BH). The system contains a solar-type G star orbiting a massive dark companion, which could be either a single BH or an inner BH + BH binary. A BH + BH binary is expected in some models where Gaia BH1 formed as a hierarchical triple, which is attractive because they avoid many of the difficulties associated with forming the system through isolated binary evolution. Our observations test the inner binary scenario. We have measured 115 precise RVs of the G star, including 40 from ESPRESSO with a precision of 3–5 m s−1, and 75 from other instruments with a typical precision of 30–100 m s−1. Our observations span 2.33 orbits of the G star and are concentrated near a periastron passage, when perturbations due to an inner binary would be largest. The RVs are well-fit by a Keplerian two-body orbit and show no convincing evidence of an inner binary. UsingREBOUNDsimulations of hierarchical triples with a range of inner periods, mass ratios, eccentricities, and orientations, we show that plausible inner binaries with periodsPinner≳ 1.5 days would have produced larger deviations from a Keplerian orbit than observed. Binaries withPinner≲ 1.5 days are consistent with the data, but these would merge within a Hubble time and would thus imply fine-tuning. We present updated parameters of Gaia BH1's orbit. The RVs yield a spectroscopic mass functionfMBH=3.9358±0.0002M—about 7000σabove the ∼2.5Mmaximum neutron star mass. Including the inclination constraint from Gaia astrometry, this implies a BH mass ofMBH= 9.27 ± 0.10M.

     
    more » « less
  2. ABSTRACT

    TOI-1259 consists of a transiting exoplanet orbiting a main-sequence star, with a bound outer white dwarf (WDs) companion. Less than a dozen systems with this architecture are known. We conduct follow-up spectroscopy on the WD TOI-1259B using the Large Binocular Telescope to better characterize it. We observe only strong hydrogen lines, making TOI-1259B a DA WD. We see no evidence of heavy element pollution, which would have been evidence of planetary material around the WD. Such pollution is seen in $\sim 25{-}50{{\ \rm per\ cent}}$ of WDs, but it is unknown if this rate is higher or lower in TOI-1259-like systems that contain a known planet. Our spectroscopy permits an improved WD age measurement of $4.05^{+1.00}_{-0.42}$ Gyr, which matches gyrochronology of the main-sequence star. This is the first of an expanded sample of similar binaries that will allow us to calibrate these dating methods and provide a new perspective on planets in binaries.

     
    more » « less
  3. ABSTRACT

    We report on the discovery and characterization of three planets orbiting the F8 star HD 28109, which sits comfortably in ${TESS}$’s continuous viewing zone. The two outer planets have periods of $\rm 56.0067 \pm 0.0003~d$ and $\rm 84.2597_{-0.0008}^{+0.0010}~d$, which implies a period ratio very close to that of the first-order 3:2 mean motion resonance, exciting transit timing variations (TTVs) of up to $\rm 60\, min$. These two planets were first identified by ${TESS}$, and we identified a third planet in the ${TESS}$photometry with a period of $\rm 22.8911 \pm 0.0004~d$. We confirm the planetary nature of all three planetary candidates using ground-based photometry from Hazelwood, ${ASTEP}$, and LCO, including a full detection of the $\rm \sim 9\, h$ transit of HD 28109 c from Antarctica. The radii of the three planets are ${\it R}_b=2.199_{-0.10}^{+0.098} ~{\rm R}_{\oplus }$, ${\it R}_c=4.23\pm 0.11~ {\rm R}_{\oplus }$, and ${\it R}_d=3.25\pm 0.11 ~{\rm R}_{\oplus }$; we characterize their masses using TTVs and precise radial velocities from ESPRESSO and HARPS, and find them to be ${\it M}_b=18.5_{-7.6}^{+9.1}~M_{\oplus }$, ${\it M}_c=7.9_{-3.0}^{+4.2}~{\rm M}_{\oplus }$, and ${\it M}_d=5.7_{-2.1}^{+2.7}~{\rm M}_{\oplus }$, making planet b a dense, massive planet while c and d are both underdense. We also demonstrate that the two outer planets are ripe for atmospheric characterization using transmission spectroscopy, especially given their position in the CVZ of James Webb Space Telescope. The data obtained to date are consistent with resonant (librating) and non-resonant (circulating) solutions; additional observations will show whether the pair is actually locked in resonance or just near-resonant.

     
    more » « less
  4. ABSTRACT

    The radial velocity method is amongst the most robust and most established means of detecting exoplanets. Yet, it has so far failed to detect circumbinary planets despite their relatively high occurrence rates. Here, we report velocimetric measurements of Kepler-16A, obtained with the SOPHIE spectrograph, at the Observatoire de Haute-Provence’s 193cm telescope, collected during the BEBOP survey for circumbinary planets. Our measurements mark the first radial velocity detection of a circumbinary planet, independently determining the mass of Kepler-16 (AB) b to be $0.313 \pm 0.039\, {\rm M}_{\rm Jup}$, a value in agreement with eclipse timing variations. Our observations demonstrate the capability to achieve photon-noise precision and accuracy on single-lined binaries, with our final precision reaching $\rm 1.5~m\, s^{-1}$ on the binary and planetary signals. Our analysis paves the way for more circumbinary planet detections using radial velocities which will increase the relatively small sample of currently known systems to statistically relevant numbers, using a method that also provides weaker detection biases. Our data also contain a long-term radial velocity signal, which we associate with the magnetic cycle of the primary star.

     
    more » « less
  5. ABSTRACT

    We present the discovery of TOI-2136 b, a sub-Neptune planet transiting a nearby M4.5V-type star every 7.85 d, identified through photometric measurements from the Transiting Exoplanet Survey Satellite (TESS) mission. The host star is located 33 pc away with a radius of R* = 0.34 ± 0.02 R⊙, a mass of $0.34\pm 0.02 \, \mathrm{M}_{\odot }$, and an effective temperature of 3342 ± 100 K. We estimate its stellar rotation period to be 75 ± 5 d based on archival long-term photometry. We confirm and characterize the planet based on a series of ground-based multiwavelength photometry, high-angular-resolution imaging observations, and precise radial velocities from Canada–France–Hawaii Telescope (CFHT)/SpectroPolarimètre InfraROUge (SPIRou). Our joint analysis reveals that the planet has a radius of 2.20 ± 0.17 R⊕ and a mass of 6.4 ± 2.4 M⊕. The mass and radius of TOI-2136 b are consistent with a broad range of compositions, from water-ice to gas-dominated worlds. TOI-2136 b falls close to the radius valley for M dwarfs predicted by thermally driven atmospheric mass-loss models, making it an interesting target for future studies of its interior structure and atmospheric properties.

     
    more » « less
  6. Abstract

    Mature super-Earths and sub-Neptunes are predicted to be ≃ Jovian radius when younger than 10 Myr. Thus, we expect to find 5–15Rplanets around young stars even if their older counterparts harbor none. We report the discovery and validation of TOI 1227b, a 0.85 ± 0.05RJ(9.5R) planet transiting a very-low-mass star (0.170 ± 0.015M) every 27.4 days. TOI 1227's kinematics and strong lithium absorption confirm that it is a member of a previously discovered subgroup in the Lower Centaurus Crux OB association, which we designate the Musca group. We derive an age of 11 ± 2 Myr for Musca, based on lithium, rotation, and the color–magnitude diagram of Musca members. The TESS data and ground-based follow-up show a deep (2.5%) transit. We use multiwavelength transit observations and radial velocities from the IGRINS spectrograph to validate the signal as planetary in nature, and we obtain an upper limit on the planet mass of ≃0.5MJ. Because such large planets are exceptionally rare around mature low-mass stars, we suggest that TOI 1227b is still contracting and will eventually turn into one of the more common <5Rplanets.

     
    more » « less
  7. Abstract

    We have collected transit times for the TRAPPIST-1 system with the Spitzer Space Telescope over four years. We add to these ground-based, HST, and K2 transit-time measurements, and revisit anN-body dynamical analysis of the seven-planet system using our complete set of times from which we refine the mass ratios of the planets to the star. We next carry out a photodynamical analysis of the Spitzer light curves to derive the density of the host star and the planet densities. We find that all seven planets’ densities may be described with a single rocky mass–radius relation which is depleted in iron relative to Earth, with Fe 21 wt% versus 32 wt% for Earth, and otherwise Earth-like in composition. Alternatively, the planets may have an Earth-like composition but enhanced in light elements, such as a surface water layer or a core-free structure with oxidized iron in the mantle. We measure planet masses to a precision of 3%–5%, equivalent to a radial-velocity (RV) precision of 2.5 cm s−1, or two orders of magnitude more precise than current RV capabilities. We find the eccentricities of the planets are very small, the orbits are extremely coplanar, and the system is stable on 10 Myr timescales. We find evidence of infrequent timing outliers, which we cannot explain with an eighth planet; we instead account for the outliers using a robust likelihood function. We forecast JWST timing observations and speculate on possible implications of the planet densities for the formation, migration, and evolution of the planet system.

     
    more » « less
  8. ABSTRACT

    We present ground- and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright (K-mag = 8.25) M3V dwarf. The planets orbit near low-order mean-motion resonances (5:3 and 2:1) and are thus expected to exhibit large transit timing variations (TTVs). Following an extensive observing campaign using eight different observatories between 2018 and 2020, we now report a clear detection of TTVs for planets c and d, with amplitudes of ∼10 min and a super-period of ∼3 yr, as well as significantly refined estimates of the radii and mean orbital periods of all three planets. Dynamical modelling of the TTVs alone puts strong constraints on the mass ratio of planets c and d and on their eccentricities. When incorporating recently published constraints from radial velocity observations, we obtain masses of $M_{\mathrm{b}}=1.48\pm 0.18\, M_\oplus$, $M_{\mathrm{c}}=6.20\pm 0.31\, M_\oplus$, and $M_{\mathrm{d}}=4.20\pm 0.16\, M_\oplus$ for planets b, c, and d, respectively. We also detect small but significant eccentricities for all three planets : eb = 0.0167 ± 0.0084, ec = 0.0044 ± 0.0006, and ed = 0.0066 ± 0.0020. Our findings imply an Earth-like rocky composition for the inner planet, and Earth-like cores with an additional He/H2O atmosphere for the outer two. TOI-270 is now one of the best constrained systems of small transiting planets, and it remains an excellent target for atmospheric characterization.

     
    more » « less
  9. ABSTRACT

    We report the discovery and characterization of a pair of sub-Neptunes transiting the bright K-dwarf TOI-1064 (TIC 79748331), initially detected in the Transiting Exoplanet Survey Satellite (TESS) photometry. To characterize the system, we performed and retrieved the CHaracterising ExOPlanets Satellite (CHEOPS), TESS, and ground-based photometry, the High Accuracy Radial velocity Planet Searcher (HARPS) high-resolution spectroscopy, and Gemini speckle imaging. We characterize the host star and determine $T_{\rm eff, \star }=4734\pm 67\,\mathrm{ K}$, $R_{\star }=0.726\pm 0.007\, \mathrm{ R}_{\odot }$, and $M_{\star }=0.748\pm 0.032\, \mathrm{ M}_{\odot }$. We present a novel detrending method based on point spread function shape-change modelling and demonstrate its suitability to correct flux variations in CHEOPS data. We confirm the planetary nature of both bodies and find that TOI-1064 b has an orbital period of Pb = 6.44387 ± 0.00003 d, a radius of Rb = 2.59 ± 0.04 R⊕, and a mass of $M_{\rm b} = 13.5_{-1.8}^{+1.7}$ M⊕, whilst TOI-1064 c has an orbital period of $P_{\rm c} = 12.22657^{+0.00005}_{-0.00004}$ d, a radius of Rc = 2.65 ± 0.04 R⊕, and a 3σ upper mass limit of 8.5 M⊕. From the high-precision photometry we obtain radius uncertainties of ∼1.6 per cent, allowing us to conduct internal structure and atmospheric escape modelling. TOI-1064 b is one of the densest, well-characterized sub-Neptunes, with a tenuous atmosphere that can be explained by the loss of a primordial envelope following migration through the protoplanetary disc. It is likely that TOI-1064 c has an extended atmosphere due to the tentative low density, however further radial velocities are needed to confirm this scenario and the similar radii, different masses nature of this system. The high-precision data and modelling of TOI-1064 b are important for planets in this region of mass–radius space, and it allow us to identify a trend in bulk density–stellar metallicity for massive sub-Neptunes that may hint at the formation of this population of planets.

     
    more » « less