Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581

Robertson, Paul; Mahadevan, Suvrath; Endl, Michael; Roy, Arpita

doi:10.1126/science.1253253

Cited by 272 publications

(221 citation statements)

References 31 publications

Supporting

Mentioning

214

Contrasting

Order By: Relevance

“…The sensitivities of the future instruments, such as ESPRESSO (Echelle SPectrograph for Rocky Exoplanet-and Stable Spectroscopic Observations) for the Very Large Telescope and CODEX (COsmic Dynamics and EXo-earth experiment) for the European Extremeley Large Telescope, aim to resolve Doppler shifts to as low as 0.1 m s −1 (Pepe et al 2014) and 0.01 m s −1 (Pasquini et al 2010) respectively. As mentioned earlier, the resultant noise from stellar activity in Sun-like stars is not considered in our assessment but will need to be taken into account at such low detection limits to avoid false positives (Robertson et al 2014). …”

Section: Searching For Exo-earths In Single Jupiter Systemsmentioning

confidence: 99%

Stable habitable zones of single Jovian planet systems

Agnew

Maddison

Thilliez

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

With continued improvement in telescope sensitivity and observational techniques, the search for rocky planets in stellar habitable zones is entering an exciting era. With so many exoplanetary systems available for follow-up observations to find potentially habitable planets, one needs to prioritise the ever-growing list of candidates. We aim to determine which of the known planetary systems are dynamically capable of hosting rocky planets in their habitable zones, with the goal of helping to focus future planet search programs. We perform an extensive suite of numerical simulations to identify regions in the habitable zones of single Jovian planet systems where Earth mass planets could maintain stable orbits, specifically focusing on the systems in the Catalog of Earth-like Exoplanet Survey Targets (CELESTA). We find that small, Earth-mass planets can maintain stable orbits in cases where the habitable zone is largely, or partially, unperturbed by a nearby Jovian, and that mutual gravitational interactions and resonant mechanisms are capable of producing stable orbits even in habitable zones that are significantly or completely disrupted by a Jovian. Our results yield a list of 13 single Jovian planet systems in CELESTA that are not only capable of supporting an Earth-mass planet on stable orbits in their habitable zone, but for which we are also able to constrain the orbits of the Earth-mass planet such that the induced radial velocity signals would be detectable with next generation instruments.

show abstract

Section: Searching For Exo-earths In Single Jupiter Systemsmentioning

confidence: 99%

Stable habitable zones of single Jovian planet systems

Agnew

Maddison

Thilliez

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Evidence for intra-spectrum RV jitter Starspots cause significant jitter in radial velocity (RV) surveys for young planets (e.g. Donati et al 2014;Robertson et al 2014). The two-temperature model assumed that the hot and cool components shared the same v sin i and v z .…”

Section: The Limitation Of a Two-temperature Modelmentioning

confidence: 99%

Placing the Spotted T Tauri Star LkCa 4 on an HR Diagram

Gully-Santiago

Herczeg

Czekala

et al. 2017

ApJ

135

111

View full text Add to dashboard Cite

Ages and masses of young stars are often estimated by comparing their luminosities and effective temperatures to pre-main sequence stellar evolution tracks, but magnetic fields and starspots complicate both the observations and evolution. To understand their influence, we study the heavily-spotted weak-lined T-Tauri star LkCa 4 by searching for spectral signatures of radiation originating from the starspot or starspot groups. We introduce a new methodology for constraining both the starspot filling factor and the spot temperature by fitting two-temperature stellar atmosphere models constructed from Phoenix synthetic spectra to a high-resolution near-IR IGRINS spectrum. Clearly discernable spectral features arise from both a hot photospheric component T hot ∼ 4100 K and to a cool component T cool ∼ 2700 − 3000 K, which covers ∼ 80% of the visible surface. This mix of hot and cool emission is supported by analyses of the spectral energy distribution, rotational modulation of colors and of TiO band strengths, and features in low-resolution optical/near-IR spectroscopy. Although the revised effective temperature and luminosity make LkCa 4 appear much younger and lower mass than previous estimates from unspotted stellar evolution models, appropriate estimates will require the production and adoption of spotted evolutionary models. Biases from starspots likely afflict most fully convective young stars and contribute to uncertainties in ages and age spreads of open clusters. In some spectral regions starspots act as a featureless "veiling" continuum owing to high rotational broadening and heavy line-blanketing in cool star spectra. Some evidence is also found for an anti-correlation between the velocities of the warm and cool components.

show abstract

“…To worsen the case, late-type M dwarfs are on average more active and display more stellar spots (e.g., Shkolnik et al 2009;Morin et al 2010;Shkolnik et al 2012;Malo et al 2014;Schmidt et al 2015), which can induce RV signals very similar to those of planetary companions (e.g., Queloz et al 2001;Paulson & Yelda 2005). Robertson et al (2014) demonstrated the importance of a careful consideration of stellar activity in exoplanet searches by demonstrating that the purported GJ581d habitable-zone exoplanet ) was most likely a false-positive signal caused by stellar spots. Overcoming this limitation is especially important in the search for very-low-mass companions that induce RV variations of low amplitudes (e.g., a few m s −1 ) comparable to stellar activity jitter.…”

Section: Introductionmentioning

confidence: 99%

A High-Precision Near-Infrared Survey for Radial Velocity Variable Low-Mass Stars Using Cshell and a Methane Gas Cell

Gagné

Plavchan

Gao

et al. 2016

ApJ

233

View full text Add to dashboard Cite

We present the results of a precise near-infrared (NIR) radial velocity (RV) survey of 32 low-mass stars with spectral types K2-M4 using CSHELL at the NASA InfraRed Telescope Facility in the K band with an isotopologue methane gas cell to achieve wavelength calibration and a novel, iterative RV extraction method. We surveyed 14 members of young (≈25-150 Myr) moving groups, the young field star εEridani, and 18 nearby (<25 pc) low-mass stars and achieved typical single-measurement precisions of 8-15 m s −1 with a long-term stability of 15-50 m s −1 over longer baselines. We obtain the best NIR RV constraints to date on 27 targets in our sample, 19 of which were never followed by high-precision RV surveys. Our results indicate that very active stars can display long-term RV variations as low as ∼25-50 m s −1 at ≈2.3125 μm, thus constraining the effect of jitter at these wavelengths. We provide the first multiwavelength confirmation of GJ876bc and independently retrieve orbital parameters consistent with previous studies. We recovered RV variabilities for HD160934AB and GJ725AB that are consistent with their known binary orbits, and nine other targets are candidate RV variables with a statistical significance of 3σ-5σ. Our method, combined with the new iSHELL spectrograph, will yield long-term RV precisions of 5 m s −1 in the NIR, which will allow the detection of super-Earths near the habitable zone of mid-M dwarfs.

show abstract

Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581

Cited by 272 publications

References 31 publications

Stable habitable zones of single Jovian planet systems

Stable habitable zones of single Jovian planet systems

Placing the Spotted T Tauri Star LkCa 4 on an HR Diagram

A High-Precision Near-Infrared Survey for Radial Velocity Variable Low-Mass Stars Using Cshell and a Methane Gas Cell

Contact Info

Product

Resources

About