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  • Dalba, Paul A.  (50)
  • Unknown  (50)
  • 1
    Online Resource
    Online Resource
    TESS Reveals HD 118203 b to be a Transiting Planet
    American Astronomical Society ; 2020
    In:  The Astronomical Journal Vol. 159, No. 6 ( 2020-06-01), p. 243-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 159, No. 6 ( 2020-06-01), p. 243-
    Abstract: The exoplanet HD 118203 b, orbiting a bright ( V  = 8.05) host star, was discovered using the radial velocity method by da Silva et al., but was not previously known to transit. Transiting Exoplanet Survey Satellite (TESS) photometry has revealed that this planet transits its host star. Nine planetary transits were observed by TESS, allowing us to measure the radius of the planet to be , and to calculate the planet mass to be . The host star is slightly evolved with an effective temperature of K and a surface gravity of . With an orbital period of days and an eccentricity of 0.314 ± 0.017, the planet occupies a transitional regime between circularized hot Jupiters and more dynamically active planets at longer orbital periods. The host star is among the 10 brightest known to have transiting giant planets, providing opportunities for both planetary atmospheric and asteroseismic studies.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/ab84f2
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2020
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds
    American Astronomical Society ; 2022
    In:  The Astronomical Journal Vol. 163, No. 4 ( 2022-04-01), p. 168-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 163, No. 4 ( 2022-04-01), p. 168-
    Abstract: LTT 1445 is a hierarchical triple M-dwarf star system located at a distance of 6.86 pc. The primary star LTT 1445A (0.257 M ⊙ ) is known to host the transiting planet LTT 1445Ab with an orbital period of 5.36 days, making it the second-closest known transiting exoplanet system, and the closest one for which the host is an M dwarf. Using Transiting Exoplanet Survey Satellite data, we present the discovery of a second planet in the LTT 1445 system, with an orbital period of 3.12 days. We combine radial-velocity measurements obtained from the five spectrographs, Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, High Accuracy Radial Velocity Planet Searcher, High-Resolution Echelle Spectrometer, MAROON-X, and Planet Finder Spectrograph to establish that the new world also orbits LTT 1445A. We determine the mass and radius of LTT 1445Ab to be 2.87 ± 0.25 M ⊕ and 1.304 − 0.060 + 0.067 R ⊕ , consistent with an Earth-like composition. For the newly discovered LTT 1445Ac, we measure a mass of 1.54 − 0.19 + 0.20 M ⊕ and a minimum radius of 1.15 R ⊕ , but we cannot determine the radius directly as the signal-to-noise ratio of our light curve permits both grazing and nongrazing configurations. Using MEarth photometry and ground-based spectroscopy, we establish that star C (0.161 M ⊙ ) is likely the source of the 1.4 day rotation period, and star B (0.215 M ⊙ ) has a likely rotation period of 6.7 days. We estimate a probable rotation period of 85 days for LTT 1445A. Thus, this triple M-dwarf system appears to be in a special evolutionary stage where the most massive M dwarf has spun down, the intermediate mass M dwarf is in the process of spinning down, while the least massive stellar component has not yet begun to spin down.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/ac50a9
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2022
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Physical Parameters of the Multiplanet Systems HD 106315 and GJ 9827* †
    American Astronomical Society ; 2021
    In:  The Astronomical Journal Vol. 161, No. 1 ( 2021-01-01), p. 47-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 161, No. 1 ( 2021-01-01), p. 47-
    Abstract: HD 106315 and GJ 9827 are two bright, nearby stars that host multiple super-Earths and sub-Neptunes discovered by K2 that are well suited for atmospheric characterization. We refined the planets’ ephemerides through Spitzer transits, enabling accurate transit prediction required for future atmospheric characterization through transmission spectroscopy. Through a multiyear high-cadence observing campaign with Keck/High Resolution Echelle Spectrometer and Magellan/Planet Finder Spectrograph, we improved the planets’ mass measurements in anticipation of Hubble Space Telescope transmission spectroscopy. For GJ 9827, we modeled activity-induced radial velocity signals with a Gaussian process informed by the Calcium II H & K lines in order to more accurately model the effect of stellar noise on our data. We measured planet masses of M b  = 4.87 ± 0.37 M ⊕ , M c  = 1.92 ± 0.49 M ⊕ , and M d  = 3.42 ± 0.62 M ⊕ . For HD 106315, we found that such activity radial velocity decorrelation was not effective due to the reduced presence of spots and speculate that this may extend to other hot stars as well ( T eff   〉  6200 K). We measured planet masses of M b  = 10.5 ± 3.1 M ⊕ and M c  = 12.0 ± 3.8 M ⊕ . We investigated all of the planets’ compositions through comparison of their masses and radii to a range of interior models. GJ 9827 b and GJ 9827 c are both consistent with a 50/50 rock-iron composition, GJ 9827 d and HD 106315 b both require additional volatiles and are consistent with moderate amounts of water or hydrogen/helium, and HD 106315 c is consistent with a ∼10% hydrogen/helium envelope surrounding an Earth-like rock and iron core.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/abca39
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 4
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    Online Resource
    TESS-Keck Survey. V. Twin Sub-Neptunes Transiting the Nearby G Star HD 63935
    American Astronomical Society ; 2021
    In:  The Astronomical Journal Vol. 162, No. 5 ( 2021-11-01), p. 215-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 162, No. 5 ( 2021-11-01), p. 215-
    Abstract: We present the discovery of two nearly identically sized sub-Neptune transiting planets orbiting HD 63935, a bright ( V = 8.6 mag), Sun-like ( T eff = 5560 K) star at 49 pc. TESS identified the first planet, HD 63935 b (TOI-509.01), in Sectors 7 and 34. We identified the second signal (HD 63935 c) in Keck High Resolution Echelle Spectrometer and Lick Automated Planet Finder radial velocity data as part of our follow-up campaign. It was subsequently confirmed with TESS photometry in Sector 34 as TOI-509.02. Our analysis of the photometric and radial velocity data yielded a robust detection of both planets with periods of 9.0600 ± 0.007 and 21.40 ± 0.0019 days, radii of 2.99 ± 0.14 and 2.90 ± 0.13 R ⊕ , and masses of 10.8 ± 1.8 and 11.1 ± 2.4 M ⊕ . We calculated densities for planets b and c consistent with a few percent of the planet mass in hydrogen/helium envelopes. We also describe our survey’s efforts to choose the best targets for James Webb Space Telescope atmospheric follow-up. These efforts suggest that HD 63935 b has the most clearly visible atmosphere of its class. It is the best target for transmission spectroscopy (ranked by the transmission spectroscopy metric, a proxy for atmospheric observability) in the so far uncharacterized parameter space comprising sub-Neptune-sized (2.6 R ⊕ 〈 R p 〈 4 R ⊕ ), moderately irradiated (100 F ⊕ 〈 F p 〈 1000 F ⊕ ) planets around G stars. Planet c is also a viable target for transmission spectroscopy, and given the indistinguishable masses and radii of the two planets, the system serves as a natural laboratory for examining the processes that shape the evolution of sub-Neptune planets.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/ac18cb
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    The TESS-Keck Survey. XI. Mass Measurements for Four Transiting Sub-Neptunes Orbiting K Dwarf TOI–1246
    American Astronomical Society ; 2022
    In:  The Astronomical Journal Vol. 163, No. 6 ( 2022-06-01), p. 293-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 163, No. 6 ( 2022-06-01), p. 293-
    Abstract: Multiplanet systems are valuable arenas for investigating exoplanet architectures and comparing planetary siblings. TOI-1246 is one such system, with a moderately bright K dwarf ( V = 11.6, K = 9.9) and four transiting sub-Neptunes identified by TESS with orbital periods of 4.31, 5.90, 18.66, and 37.92 days. We collected 130 radial velocity observations with Keck/HIRES and TNG/HARPS-N to measure planet masses. We refit the 14 sectors of TESS photometry to refine planet radii (2.97 ± 0.06 R ⊕ , 2.47 ± 0.08 R ⊕ , 3.46 ± 0.09 R ⊕ , and 3.72 ± 0.16 R ⊕ ) and confirm the four planets. We find that TOI-1246 e is substantially more massive than the three inner planets (8.1 ± 1.1 M ⊕ , 8.8 ± 1.2 M ⊕ , 5.3 ± 1.7 M ⊕ , and 14.8 ± 2.3 M ⊕ ). The two outer planets, TOI-1246 d and TOI-1246 e, lie near to the 2:1 resonance ( P e / P d = 2.03) and exhibit transit-timing variations. TOI-1246 is one of the brightest four-planet systems, making it amenable for continued observations. It is one of only five systems with measured masses and radii for all four transiting planets. The planet densities range from 0.70 ± 0.24 to 3.21 ± 0.44 g cm −3 , implying a range of bulk and atmospheric compositions. We also report a fifth planet candidate found in the RV data with a minimum mass of 25.6 ± 3.6 M ⊕ . This planet candidate is exterior to TOI-1246 e, with a candidate period of 93.8 days, and we discuss the implications if it is confirmed to be planetary in nature.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/ac69e5
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2022
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 6
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    Online Resource
    Transits of Known Planets Orbiting a Naked-eye Star
    American Astronomical Society ; 2020
    In:  The Astronomical Journal Vol. 160, No. 3 ( 2020-09-01), p. 129-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 160, No. 3 ( 2020-09-01), p. 129-
    Abstract: Some of the most scientifically valuable transiting planets are those that were already known from radial velocity (RV) surveys. This is primarily because their orbits are well characterized and they preferentially orbit bright stars that are the targets of RV surveys. The Transiting Exoplanet Survey Satellite (TESS) provides an opportunity to survey most of the known exoplanet systems in a systematic fashion to detect possible transits of their planets. HD 136352 (Nu 2 Lupi) is a naked-eye ( V  = 5.78) G-type main-sequence star that was discovered to host three planets with orbital periods of 11.6, 27.6, and 108.1 days via RV monitoring with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. We present the detection and characterization of transits for the two inner planets of the HD 136352 system, revealing radii of R ⊕ and R ⊕ for planets b and c, respectively. We combine new HARPS observations with RV data from the Keck/High Resolution Echelle Spectrometer and the Anglo-Australian Telescope, along with TESS photometry from Sector 12, to perform a complete analysis of the system parameters. The combined data analysis results in extracted bulk density values of g cm −3 and g cm −3 for planets b and c, respectively, thus placing them on either side of the radius valley. The combination of the multitransiting planet system, the bright host star, and the diversity of planetary interiors and atmospheres means this will likely become a cornerstone system for atmospheric and orbital characterization of small worlds.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/aba835
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2020
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 7
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    Revised Architecture and Two New Super-Earths in the HD 134606 Planetary System
    American Astronomical Society ; 2024
    In:  The Astronomical Journal Vol. 167, No. 4 ( 2024-04-01), p. 155-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 167, No. 4 ( 2024-04-01), p. 155-
    Abstract: Multiplanet systems exhibit a diversity of architectures that diverge from the solar system and contribute to the topic of exoplanet demographics. Radial velocity (RV) surveys form a crucial component of exoplanet surveys, as their long observational baselines allow for searches for more distant planetary orbits. This work provides a significantly revised architecture for the multiplanet system HD 134606 using both HARPS and UCLES RVs. We confirm the presence of previously reported planets b, c, and d with periods of 12.0897 − 0.0018 + 0.0019 , 58.947 − 0.054 + 0.056 , and 958.7 − 5.9 + 6.3 days and masses of 9.14 − 0.63 + 0.65 , 11.0 ± 1, and 44.5 ± 2.9 Earth masses, respectively, with the planet d orbit significantly revised to over double that originally reported. We report two newly detected super-Earths, e and f, with periods of 4.31943 − 0.00068 + 0.00075 and 26.9 − 0.017 + 0.019 days and masses of 2.31 − 0.35 + 0.36 and 5.52 − 0.73 + 0.74 Earth masses, respectively. In addition, we identify a linear trend in the RV time series, and the cause of this acceleration is deemed to be a newly detected massive companion with a very long orbital period. HD 134606 now displays four low-mass planets in a compact region near the star, one gas giant further out in the habitable zone, an additional companion in the outer regime, and a low-mass M dwarf stellar companion at large separation, making it an intriguing target for system formation/evolution studies. The location of planet d in the habitable zone proves to be an exciting candidate for future space-based direct imaging missions, whereas continued RV observations of this system are recommended for understanding the nature of the massive, long-period companion.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/ad2461
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2024
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 8
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    The TESS-Keck Survey. XX. 15 New TESS Planets and a Uniform RV Analysis of All Survey Targets
    American Astronomical Society ; 2024
    In:  The Astrophysical Journal Supplement Series Vol. 272, No. 2 ( 2024-06-01), p. 32-
    Details
    In: The Astrophysical Journal Supplement Series, American Astronomical Society, Vol. 272, No. 2 ( 2024-06-01), p. 32-
    Abstract: The Transiting Exoplanet Survey Satellite (TESS) has discovered hundreds of new worlds, with TESS planet candidates now outnumbering the total number of confirmed planets from Kepler. Owing to differences in survey design, TESS continues to provide planets that are better suited for subsequent follow-up studies, including mass measurement through radial velocity (RV) observations, compared to Kepler targets. In this work, we present the TESS-Keck Survey’s (TKS) Mass Catalog: a uniform analysis of all TKS RV survey data that has resulted in mass constraints for 126 planets and candidate signals. This includes 58 mass measurements that have reached ≥5 σ precision. We confirm or validate 32 new planets from the TESS mission either by significant mass measurement (15) or statistical validation (17), and we find no evidence of likely false positives among our entire sample. This work also serves as a data release for all previously unpublished TKS survey data, including 9,204 RV measurements and associated activity indicators over our three-year survey. We took the opportunity to assess the performance of our survey and found that we achieved many of our goals, including measuring the mass of 38 small ( 〈 4 R ⊕ ) planets, nearly achieving the TESS mission’s basic science requirement. In addition, we evaluated the performance of the Automated Planet Finder as survey support and observed meaningful constraints on system parameters, due to its more uniform phase coverage. Finally, we compared our measured masses to those predicted by commonly used mass–radius relations and investigated evidence of systematic bias.
    Type of Medium: Online Resource
    ISSN: 0067-0049 , 1538-4365
    URL: Article
    DOI: 10.3847/1538-4365/ad4484
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2024
    detail.hit.zdb_id: 2961-0
    detail.hit.zdb_id: 2006860-8
    SSG: 16,12
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  • 9
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    The TESS-Keck Survey. II. An Ultra-short-period Rocky Planet and Its Siblings Transiting the Galactic Thick-disk Star TOI-561
    American Astronomical Society ; 2021
    In:  The Astronomical Journal Vol. 161, No. 2 ( 2021-02-01), p. 56-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 161, No. 2 ( 2021-02-01), p. 56-
    Abstract: We report the discovery of TOI-561, a multiplanet system in the galactic thick disk that contains a rocky, ultra-short-period planet. This bright ( V = 10.2) star hosts three small transiting planets identified in photometry from the NASA TESS mission: TOI-561 b (TOI-561.02, P = 0.44 days, R p = 1.45 ± 0.11 R ⊕ ), c (TOI-561.01, P = 10.8 days, R p = 2.90 ± 0.13 R ⊕ ), and d (TOI-561.03, P = 16.3 days, R p = 2.32 ± 0.16 R ⊕ ). The star is chemically ([Fe/H] = −0.41 ± 0.05, [ α /Fe] = +0.23 ± 0.05) and kinematically consistent with the galactic thick-disk population, making TOI-561 one of the oldest (10 ± 3 Gyr) and most metal-poor planetary systems discovered yet. We dynamically confirm planets b and c with radial velocities from the W. M. Keck Observatory High Resolution Echelle Spectrometer. Planet b has a mass and density of 3.2 ± 0.8 M ⊕ and g cm −3 , consistent with a rocky composition. Its lower-than-average density is consistent with an iron-poor composition, although an Earth-like iron-to-silicates ratio is not ruled out. Planet c is 7.0 ± 2.3 M ⊕ and 1.6 ± 0.6 g cm −3 , consistent with an interior rocky core overlaid with a low-mass volatile envelope. Several attributes of the photometry for planet d (which we did not detect dynamically) complicate the analysis, but we vet the planet with high-contrast imaging, ground-based photometric follow-up, and radial velocities. TOI-561 b is the first rocky world around a galactic thick-disk star confirmed with radial velocities and one of the best rocky planets for thermal emission studies.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/abd409
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 10
    Online Resource
    Online Resource
    The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 Day Orbit with the Automated Planet Finder Telescope*
    American Astronomical Society ; 2022
    In:  The Astronomical Journal Vol. 163, No. 2 ( 2022-02-01), p. 61-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 163, No. 2 ( 2022-02-01), p. 61-
    Abstract: We report the discovery of TOI-2180 b, a 2.8 M J giant planet orbiting a slightly evolved G5 host star. This planet transited only once in Cycle 2 of the primary Transiting Exoplanet Survey Satellite (TESS) mission. Citizen scientists identified the 24 hr single-transit event shortly after the data were released, allowing a Doppler monitoring campaign with the Automated Planet Finder telescope at Lick Observatory to begin promptly. The radial velocity observations refined the orbital period of TOI-2180 b to be 260.8 ± 0.6 days, revealed an orbital eccentricity of 0.368 ± 0.007, and discovered long-term acceleration from a more distant massive companion. We conducted ground-based photometry from 14 sites spread around the globe in an attempt to detect another transit. Although we did not make a clear transit detection, the nondetections improved the precision of the orbital period. We predict that TESS will likely detect another transit of TOI-2180 b in Sector 48 of its extended mission. We use giant planet structure models to retrieve the bulk heavy-element content of TOI-2180 b. When considered alongside other giant planets with orbital periods over 100 days, we find tentative evidence that the correlation between planet mass and metal enrichment relative to stellar is dependent on orbital properties. Single-transit discoveries like TOI-2180 b highlight the exciting potential of the TESS mission to find planets with long orbital periods and low irradiation fluxes despite the selection biases associated with the transit method.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/ac415b
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2022
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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