Accurate masses and radii of normal stars: modern results and applications

Torres, Guillermo; Andersen, J.; Giménez, Á.

doi:10.1007/s00159-009-0025-1

Cited by 1,371 publications

(1,771 citation statements)

References 149 publications

Supporting

Mentioning

1,670

Contrasting

Unclassified

Order By: Relevance

“…We estimated the stellar mass and radius using empirical relationships 23 based on non-interacting binary systems that parameterize R star and M star as functions of log g, T eff , and [Fe/H]. We propagated the errors on the three SME-derived inputs to obtain R star = 0.74 ± 0.05 R sun and M star = 0.83 ± 0.05 M sun .…”

Section: Methodsmentioning

confidence: 99%

“…The stellar effective temperature and iron abundance were obtained by fitting stellar-atmosphere models 21 to iodine-free HIRES spectra 9 , subject to a constraint on the surface gravity based on stellar-evolutionary models 22 . We estimated the stellar mass and radius from empirically calibrated relationships between those spectroscopic parameters 23 . The refined stellar radius led to a refined planet radius.…”

Section: Planetary Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

A rocky composition for an Earth-sized exoplanet

Howard

Sanchis-Ojeda

Marcy

et al. 2013

Nature

191

157

View full text Add to dashboard Cite

Planets with sizes between that of Earth (with radius R ⊕ ) and Neptune (about 4 R ⊕ ) are now known to be common around Sun-like stars 1,2,3 . Most such planets have been discovered through the transit technique, by which the planet's size can be determined from the fraction of starlight blocked by the planet as it passes in front of its star. Measuring the planet's mass-and hence its density, which is a clue to its composition-is more difficult. Planets of size 2-4 R ⊕ have proven to have a wide range of densities, implying a diversity of compositions 4,5 , but these measurements did not extend down to planets as small as Earth. Here we report Doppler spectroscopic measurements of the mass of the Earth-sized planet Kepler-78b, which orbits its host star every 8.5 hours (ref. 6). Given a radius of 1.20 ± 0.09 R ⊕ and mass of 1.69 ± 0.41 M ⊕ , the planet's mean density of 5.3 ± 1.8 g cm -3 is similar to the Earth's, suggesting a composition of rock and iron.Kepler-78 is one of approximately 150,000 stars whose brightness was precisely measured at 30-minute intervals for four years by the NASA Kepler spacecraft 7 . This star is somewhat smaller, less massive, and younger than the Sun (Table 1). Every 8.5 hours the star's brightness declines by 0.02% as the planet Kepler-78b transits (passes in front of) the stellar disk. The planet's radius was originally measured 6 to be 1.16 !!.!" !!.!" R ⊕ . The mass could not be measured, although masses >8 M ⊕ could be ruled out because the planet's gravity would have deformed the star and produced brightness variations that were not detected.We measured the mass of Kepler-78b by tracking the line-of-sight component of the host star's motion (the radial velocity, RV) due to the gravitational force of the planet. The RV analysis is challenging not only because the signal is expected to be small (~1-3 m s -1 ) but also because the apparent Doppler shifts due to rotating starspots are much larger (~50 m s -1 peak-to-peak). Nevertheless the detection proved to be possible, thanks to the precisely known orbital period and phase of Kepler-78b that cleanly separated the timescale of spot variations (P rot ≈ 12.5 days) from the much shorter timescale of the planetary orbit (P ≈ 8.5 hours). We adopted a strategy of intensive Doppler measurements spanning 6-8 hours per night, long enough to cover nearly the entire orbit and short enough for the spot variations to be nearly frozen out.We measured RVs using optical spectra of Kepler-78 that we obtained from the High Resolution Echelle Spectrometer (HIRES) 8 on the 10-m Keck I Telescope. These Doppler shifts were computed relative to a template spectrum with a standard algorithm 9 that uses a spectrum of molecular iodine superposed on the stellar spectrum as a reference for the wavelength scale and instrumental profile of HIRES (Supplementary Table 1). Exposures lasted 15-30 minutes depending on conditions and produced RVs with 1.5-2.0 m s -1 uncertainties. The time series of RVs spans 38 days, with large velocity offsets between nights ...

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Planetary Propertiesmentioning

confidence: 99%

A rocky composition for an Earth-sized exoplanet

Howard

Sanchis-Ojeda

Marcy

et al. 2013

Nature

191

157

View full text Add to dashboard Cite

show abstract

“…This relationship assumes that no bright companions are present, which can only be confirmed with more advanced followup. From this temperature, and making the assumption that the star is on the main sequence, stellar models allow a stellar radius and mass to be estimated (Torres, Andersen & Giménez 2010). Temperature uncertainty was estimated from the RMS of the temperature from each colour estimate, or 150 K if the RMS was smaller than this value.…”

Section: Stellar Parameter Fitsmentioning

confidence: 99%

Single transit candidates from K2: detection and period estimation

Osborn

Armstrong

Brown

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

Photometric surveys such as Kepler have the precision to identify exoplanet and eclipsing binary candidates from only a single transit. K2, with its 75 d campaign duration, is ideally suited to detect significant numbers of single-eclipsing objects. Here we develop a Bayesian transit-fitting tool ('Namaste: An Mcmc Analysis of Single Transit Exoplanets') to extract orbital information from single transit events. We achieve favourable results testing this technique on known Kepler planets, and apply the technique to seven candidates identified from a targeted search of K2 campaigns 1, 2 and 3. We find EPIC203311200 to host an excellent exoplanet candidate with a period, assuming zero eccentricity, of 540 +410 −230 d and a radius of 0.51 ± 0.05R Jup . We also find six further transit candidates for which more follow-up is required to determine a planetary origin. Such a technique could be used in the future with TESS, PLATO and ground-based photometric surveys such as NGTS, potentially allowing the detection of planets in reach of confirmation by Gaia.

show abstract

“…Note that ξ * is of order unity for main sequence stars with M * 2M ⊙ (e.g., Torres et al 2010;Eker et al 2015).…”

Section: Simple Order-of-magnitude Estimatementioning

confidence: 99%

Optical–infrared flares and radio afterglows by Jovian planets inspiraling into their host stars

Yamazaki

Hayasaki

Loeb

2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

When a planet inspirals into its host star, it releases gravitational energy which is converted into an expanding bubble of hot plasma. We study the radiation from the bubble and show that it includes prompt optical-infrared emission and a subsequent radio afterglow. The prompt emission from M31 and Large Magellanic Cloud is detectable by optical-near infrared transient surveys with a large field of view. The subsequent radio afterglows are detectable for 10 3−4 years. The event rate depends on uncertain parameters in the formation and dynamics of giant planets. Future observation of the rate will constrain related theoretical models. If the event rate is high ( a few events per year), the circumstellar disk must typically be massive as suggested by recent numerical simulations.

show abstract

Accurate masses and radii of normal stars: modern results and applications

Cited by 1,371 publications

References 149 publications

A rocky composition for an Earth-sized exoplanet

A rocky composition for an Earth-sized exoplanet

Single transit candidates from K2: detection and period estimation

Optical–infrared flares and radio afterglows by Jovian planets inspiraling into their host stars

Contact Info

Product

Resources

About