Browsing by Author "Jeffers, S. V."

Now showing items 1-11 of 11

    • Analysis of combined radial velocities and activity of BD+20 1790: : evidence supporting the existence of a planetary companion 

      Hernán-Obispo, M.; Tuomi, Mikko; Gálvez-Ortiz, M. C.; Golovin, A.; Barnes, J. R.; Jones, Hugh; Kane, S. R.; Pinfield, D.; Jenkins, J. S.; Petit, P.; Anglada-Escudé, G.; Marsden, S. C.; Catalán, S.; Jeffers, S. V.; Castro, E. de; Cornide, M.; Garcés, A.; Jones, M. I.; Gorlova, N.; Andreev, M. (2015-04-01)
      This paper presents the simultaneous Bayesian analysis of the radial velocity and activity indices for the K5Ve active star BD+20 1790, that was proposed to host a close-in massive planet by Hern\'an-Obispo et al. (2010). ...

    • A candidate super-Earth planet orbiting near the snow line of Barnard's star 

      Ribas, I.; Tuomi, M.; Reiners, A.; Butler, R. P.; Morales, J. C.; Perger, M.; Dreizler, S.; Rodríguez-López, C.; Hernández, J. I. González; Rosich, A.; Feng, F.; Trifonov, T.; Vogt, S. S.; Caballero, J. A.; Hatzes, A.; Herrero, E.; Jeffers, S. V.; Lafarga, M.; Murgas, F.; Rodríguez, E.; Strachan, J. B. P.; Tal-Or, L.; Teske, J.; Toledo-Padrón, B.; Zechmeister, M.; Quirrenbach, A.; Amado, P. J.; Azzaro, M.; Béjar, V. J. S.; Barnes, J. R.; Berdiñas, Z. M.; Coleman, G.; Cortés-Contreras, M.; Crane, J.; Engle, S. G.; Guinan, E. F.; Haswell, C. A.; Henning, Th; Holden, B.; Jones, H. R. A.; Kaminski, A.; Kiraga, M.; Kürster, M.; López-González, M. J.; Montes, D.; Morin, J.; Ofir, A.; Pallé, E.; Rebolo, R.; Reffert, S.; Schweitzer, A.; Seifert, W.; Shectman, S. A.; Staab, D.; Street, R. A.; Mascareño, A. Suárez; Tsapras, Y.; Anglada-Escudé, G. (2018-11-15)
      Barnard’s star is a red dwarf, and has the largest proper motion (apparent motion across the sky) of all known stars. At a distance of 1.8 parsecs, it is the closest single star to the Sun; only the three stars in the α ...

    • The CARMENES search for exoplanets around M dwarfs. Characterization of the nearby ultra-compact multiplanetary system YZ Ceti 

      Stock, S.; Kemmer, J.; Reffert, S.; Trifonov, T.; Kaminski, A.; Dreizler, S.; Quirrenbach, A.; Caballero, J. A.; Reiners, A.; Jeffers, S. V.; Anglada-Escudé, G.; Ribas, I.; Amado, P. J.; Barrado, D.; Barnes, J. R.; Bauer, F. F.; Berdiñas, Z. M.; Béjar, V. J. S.; Coleman, G. A. L.; Cortés-Contreras, M.; Díez-Alonso, E.; Domínguez-Fernández, A. J.; Espinoza, N.; Haswell, C. A.; Hatzes, A.; Henning, T.; Jenkins, J. S.; Jones, H. R. A.; Kossakowski, D.; Kürster, M.; Lafarga, M.; Lee, M. H.; González, M. J. López; Montes, D.; Morales, J. C.; Morales, N.; Pallé, E.; Pedraz, S.; guez, E. Rodrí; Rodríguez-López, C.; Zechmeister, M. (2020-02-07)
      Context. The nearby ultra-compact multiplanetary system YZ Ceti consists of at least three planets, and a fourth tentative signal. The orbital period of each planet is the subject of discussion in the literature due to ...

    • Dense spot coverage and polar caps on SV Cam 

      Jeffers, S. V.; Cameron, A. Collier; Barnes, J. R.; Aufdenberg, J. P. (2006-08)
      We have used spectrophotometric data from nine Hubble Space Telescope orbits to eclipse-map the primary component of the RS CVn binary SV Cam. From these observations and its HIPPARCOS parallax we find that the surface ...

    • The effect of M dwarf starspot activity on low-mass planet detection thresholds 

      Barnes, J. R.; Jeffers, S. V.; Jones, H.R.A. (2011-04)
      In light of the growing interest in searching for low mass, rocky planets, we investigate the impact of starspots on radial velocity searches for earth-mass planets in orbit about M dwarf stars. Since new surveys targeting ...

    • A multiplanet system of super-Earths orbiting the brightest red dwarf star GJ 887 

      Jeffers, S. V.; Dreizler, S.; Barnes, J. R.; Haswell, C. A.; Nelson, R. P.; Rodríguez, E.; Lopez-Gonzalez, M. J.; Morales, N.; Luque, R.; Zechmeister, M.; Vogt, S. S.; Jenkins, J. S.; Palle, E.; Berdinas, Z. M.; Coleman, G. A. L.; Diaz, M. R.; Ribas, I.; Jones, H. R. A.; Butler, R. P.; Tinney, C. G.; Bailey, J.; Carter, B. D.; ~O'Toole, S.; Wittenmyer, R. A.; Crane, J. D.; Feng, F.; Shectman, S. A.; Teske, J.; Reiners, A.; Amado, P. J.; Anglada-Escude, G.; . (2020-06-26)
      The closet exoplanets to the Sun provide opportunities for detailed characterization of planets outside the Solar System. We report the discovery, using radial velocity measurements, of a compact multiplanet system of ...

    • NO EVIDENCE for ACTIVITY CORRELATIONS in the RADIAL VELOCITIES of KAPTEYN'S STAR 

      Anglada-Escudé, G.; Tuomi, Mikko; Arriagada, P.; Zechmeister, M.; Jenkins, J. S.; Ofir, A.; Dreizler, S.; Gerlach, E.; Marvin, C. J.; Reiners, A.; Jeffers, S. V.; Butler, R. Paul; Vogt, S. S.; Amado, P. J.; Rodríguez-López, C.; Berdiñas, Z. M.; Morin, J.; Crane, J. D.; Shectman, S. A.; Díaz, M. R.; Sarmiento, L. F.; Jones, H. R A (2016-10-20)
      Stellar activity may induce Doppler variability at the level of a few m s-1 which can then be confused by the Doppler signal of an exoplanet orbiting the star. To first order, linear correlations between radial velocity ...

    • Precision radial velocities of 15 M5-M9 dwarfs 

      Barnes, J. R.; Jenkins, J. S.; Jones, H. R A; Jeffers, S. V.; Rojo, P.; Arriagada, P.; Jordán, A.; Minniti, D.; Tuomi, Mikko; Pinfield, David; Anglada-Escudé, G. (2014-04-11)
      We present radial velocity measurements of a sample ofM5V-M9Vstars from our Red-Optical Planet Survey, operating at 0.652-1.025 μm. Radial velocities for 15 stars, with rms precision down to 2.5m-1 over a week-long time-scale, ...

    • Recovering planet radial velocity signals in the presence of starspot activity in fully convective stars 

      Barnes, John; Anglada Escude, Guillem; Tuomi, Mikko; Jones, Hugh; Feng, F.; Jeffers, S. V.; Haswell, C. A.; Jenkins, J. S.; Petit, P. (2017-04-01)
      Accounting for stellar activity is a crucial component of the search for ever-smaller planets orbiting stars of all spectral types. We use Doppler imaging methods to demonstrate that starspot-induced radial velocity ...

    • Surprisingly different starspot distributions on the near equal-mass equal-rotation-rate stars in the M dwarf binary GJ 65 AB 

      Barnes, J. R.; Jeffers, S. V.; Haswell, C. A.; Jones, H. R. A.; Shulyak, D.; Pavlenko, Ya V.; Jenkins, J. S. (2017-10-11)
      We aim to understand how stellar parameters such as mass and rotation impact the distribution of starspots on the stellar surface. To this purpose, we have used Doppler imaging to reconstruct the surface brightness ...

    • Two planets around Kapteyn's star: a cold and a temperate super-Earth orbiting the nearest halo red dwarf 

      Anglada-Escude, Guillem; Arriagada, P.; Tuomi, Mikko; Zechmeister, M.; Jenkins, J. S.; Ofir, A.; Dreizler, S.; Gerlach, E.; Marvin, C. J.; Reiners, A.; Jeffers, S. V.; Butler, R.P.; Vogt, S. S.; Amado, P. J.; Gerlach, E.; Rodríguez-López, C.; Berdiñas, Z. M.; Morin, J.; Crane, J. D.; Shectman, S. A.; Thompson, Ian B.; Diaz, M.; Rivera, E.; Sarmiento, L. F.; Jones, Hugh (2014-09-01)
      Exoplanets of a few Earth masses can be now detected around nearby low-mass stars using Doppler spectroscopy. In this Letter, we investigate the radial velocity variations of Kapteyn's star, which is both a sub-dwarf M-star ...