Scientific Publications

As part of our engagement and scientific efforts, we're presenting some of the key results from the Exoplanet Science Initiative below.



  • 2016 - "A Characteristic Transmission Spectrum dominated by H2O applies to the majority of HST/WFC3 exoplanet observations"
    Iyer, Aishwarya R.; Swain, Mark R.; Zellem, Robert T.; Line, Michael R.; Roudier, Gael; Rocha, Graça; Livingston, John H.

    Water is ubiquitous among hot Jupiter exoplanets and about half of their atmospheres are covered by opacity sources such as clouds, haze/aerosols. 10 out of 19 hot Jupiters observed using HST/WFC3 within the last decade have shown a significant water detection in their atmospheres. Our method allows for coherent averaging of the individual transmission spectra of these planets to produce a Representative Spectrum that is characteristic of hot Jupiter atmospheres. Additionally, we are also able to quantify that about half of these atmospheres are being blocked by cloud, haze or aerosols that affect our estimate for the true water content in hot Jupiters.



  • 2016 - “A map of the large day-night temperature gradient of a super-Earth exoplanet”
    Demory, Brice-Olivier; Gillon, Michael; de Wit, Julien; Madhusudhan, Nikku; Bolmont, Emeline; Heng, Kevin; Kataria, Tiffany; Lewis, Nikole; Hu, Renyu; Krick, Jessica; Stamenković, Vlada; Benneke, Björn; Kane, Stephen; Queloz, Didier

    55 Cancri e, approximately 40 light-years away in the constellation Cancer, has a radius twice Earth’s, and a mass 8 times greater. The paper reports a longitudinal thermal brightness map of 55 Cancri e obtained by the Spitzer Space Telescope, the first such map observed for any super-Earth class of exoplanets. The map tells us that the temperature contrast between the planet's dayside and the nightside is greater than 1000 K, and efficient energy transport occurs in the planet's dayside.



  • 2016 - “The MUSCLES Treasury Survey III: X-ray to Infrared Spectra of 11 M and K Stars”
    Loyd, R. O. P.; France, Kevin; Youngblood, Allison; Schneider, Christian; Brown, Alexander; Hu, Renyu; Linsky, Jeffrey; Froning, Cynthia S.; Redfield, Seth; Rugheimer, Sarah; Tian, Feng

    The shape and the absolute flux of a star's emission control the atmospheric chemistry of exoplanets around it. Using new Hubble Space Telescope observations, panchromatic (X-ray to mid-IR) spectra of 11 nearby planet-hosting low-mass (M to K) stars are derived. This database of stellar spectra is the foundation of modeling atmospheric photochemistry and assessing potential biosignature gases for rocky exoplanets.



  • 2016 - “Detection of Linearly Polarized 6.9 mm Continuum Emission from the Class 0 Young Stellar Object NGC1333 IRAS4A”
    Liu, Hauyu Baobab; Lai, Shih-Ping; Hasegawa, Yasuhiro; Hirano, Naomi; Rao, Ramprasad; Li, I.-Hsiu; Fukagawa, Misato; Girart, Josep M.; Carrasco-González, Carlos; Rodríguez, Luis F.

    Dust growth, a first step of planet formation, can change the mass and the shape of dust grains. The detection of linearly polarized dust continuum emission at 6.9 mm can serve as a probe of how dust shape evolves, following dust growth. We demonstrate this possibility by reporting new JVLA, high angular resolution observations toward a Class 0 YSO.



  • 2016 - “Forming Chondrites in a Solar Nebula with Magnetically induced Turbulence”
    Hasegawa, Yasuhiro; Turner, Neal J.; Masiero, Joseph; Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi

    Chondritic meteorites provide valuable opportunities to investigate the origins of the solar system. We identify under what conditions chondrule formation and accretion can be realized in the solar nebula, making use of the currently available meteoritic date. The data include the present asteroid belt mass, the formation timescale of chondrules, the magnetic field strength of the nebula derived from chondrules in Semarkona.



  • 2016 - “Planetary System Formation in the Protoplanetary Disk around HL Tauri”
    Akiyama, Eiji; Hasegawa, Yasuhiro; Hayashi, Masahiko; Iguchi, Satoru

    ALMA long-baseline science verification campaign reveals the astonishing multiple gap structure in the circumstellar disk around HL Tau. We reanalyze the data and discuss how such a gap structure is generated. Assuming that the gaps are opened up by unseen massive bodies, gravitational instabilities may be a mechanism to form the bodies in the outer region of the disk. ALMA’s unprecedented high spatial resolution observations will revolutionize our picture of planet formation.



  • 2016 - “Absence of Significant Cold Disks in Young Stellar Objects Exhibiting Repetitive Optical Outbursts”
    Liu, Hauyu Baobab; Galván-Madrid, Roberto; Vorobyov, Eduard I.; Kóspál, Ágnes; Rodríguez, Luis F.; Dunham, Michael M.; Hirano, Naomi; Henning, Thomas; Takami, Michihiro; Dong, Ruobing; Hashimoto, Jun; Hasegawa, Yasuhiro; Carrasco-González, Carlos

    Many low-mass YSOs may have experienced repetitive outburst events until they finally arrive at the main-sequence stage. We report SMA 1.3 mm high angular resolution observations toward the so-called EXors. We find that most of them have low dust masses while the previous IR observations suggest that they should have enough gas masses. Our observations therefore infer that most of EXors may not have cold dust, which would be valuable information to understand how repetitive outbursts occur around YSOs.



  • 2016 - “Chondrule Formation via Impact Jetting Triggered by Planetary Accretion”
    Hasegawa, Yasuhiro; Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi

    Chondrules are the primitive materials in the solar system, which enables one to explore the origins of the solar system. We investigate how and what amount of chondrules can be formed via impact jetting that can occur at planetesimal collisions. We find that formation of protoplanets leads to a large number of chondrule-forming impacts with a certain timescale, both of which are consistent with the chondritic data.



  • Published Papers in 2015



  • 2015 - “Viscous Instability Triggered by Layered Accretion in Protoplanetary Disks”
    Hasegawa, Yasuhiro; Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi

    The properties of protoplanetary disks, the birthplace of planets, are determined by magnetically induced turbulence. The previous theoretical studies suggest that the degree of disk turbulence varies as a function of the distance from the central star. We find that a viscous instability can take place at the boundary between high- and low-turbulent regions, which can considerably affect disk evolution and planet formation.



  • 2015 - “XO-2b: A Hot Jupiter with a Variable Host Star That Potentially Affects Its Measured Transit Depth”
    Zellem, Robert T.; Griffith, Caitlin A.; Pearson, Kyle A.; Turner, Jake D.; Henry, Gregory W.; Williamson, Michael H.; Ryleigh Fitzpatrick, M.; Teske, Johanna K.; Biddle, Lauren I.

    We conduct a multi-year study of the transiting exoplanet XO-2b to measure its Rayleigh scattering slope to place upper limits on its optically-thick radius and better constrain its molecular abundances. We also find that with mulity-year ground-based monitoring that its host star is active, potentially at the level that could affect future high-precision measurements of the signal of the exoplanet and alter the interpretations about its atmospheric properties.



  • 2015 - “Studying Atmosphere-Dominated Kepler Phase Curves”
    Shporer, Avi; Hu, Renyu

    In this paper we have shown that gas giant exoplanets on short orbital periods have non-uniform cloud coverage. We concluded this from the detection of non-uniform reflected star light, in visible light, across different planet longitudes. This has several implications regarding the structure and chemical composition of planetary atmospheres of such exoplanets.



  • 2015 - “A Characteristic Transmission Spectrum dominated by H2O applies to the majority of HST/WFC3 exoplanet observations”
    Iyer, Swain, Zellem, Line, Roudier, Rocha, Livingston

    JPL intern Aishwarya Iyer and colleagues averaged the spectra from 19 transiting exoplanets taken with the Hubble Space Telescope and found a characteristic spectrum for those planets which had a reported water detection.

    Water is ubiquitous among hot Jupiter exoplanets and about half of their atmospheres are covered by opacity sources such as clouds, haze/aerosols. 10 out of 19 hot Jupiters observed using HST/WFC3 within the last decade have shown a significant water detection in their atmospheres. Our method allows for coherent averaging of the individual transmission spectra of these planets to produce a Representative Spectrum that is characteristic of hot Jupiter atmospheres. Additionally, we are also able to quantify that about half of these atmospheres are being blocked by cloud, haze or aerosols that affect our estimate for the true water content in hot Jupiters.