Evidence of a Sub-Saturn around EPIC~211945201

We report here strong evidence for a sub-Saturn around EPIC~211945201 and confirm its planetary nature. EPIC~211945201b was found to be a planetary candidate from {\it K2} photometry in Campaigns 5 \& 16, transiting a bright star ($V_{\rm mag}=10.15$, G0 spectral type) in a 19.492 day orbit. However, the photometric data combined with false positive probability calculations using VESPA was not sufficient to confirm the planetary scenario. Here we present high-resolution spectroscopic follow-up of the target using the PARAS spectrograph (19 radial velocity observations) over a time-baseline of 420 days. We conclusively rule out the possibility of an eclipsing binary system and confirm the 2-$\sigma$ detection of a sub-Saturn planet. The confirmed planet has a radius of 6.12$\pm0.1$$~R_{\oplus}$, and a mass of $27_{-12.6}^{+14}$~$M_{\oplus}$. We also place an upper limit on the mass (within the 3-$\sigma$ confidence interval) at 42~$M_{\oplus}$ above the nominal value. This results in the Saturn-like density of $0.65_{-0.30}^{+0.34}$ g~cm$^{-3}$. Based on the mass and radius, we provide a preliminary model-dependent estimate that the heavy element content is 60-70 \% of the total mass. This detection is important as it adds to a sparse catalog of confirmed exoplanets with masses between 10-70 $M_{\oplus}$ and radii between 4-8 $R_{\oplus}$, whose masses and radii are measured to a precision of 50\% or better (only 23 including this work).Comment: Accepted for publication in The Astronomical Journal, 17 pages, 8 figure

PARAS-2 precision radial velocimeter: optical and mechanical design of a fiber-fed high resolution spectrograph under vacuum and temperature control

We present here the optical and mechanical design of a fiber-fed High-resolution spectrograph at resolution (R) = 100,000 which will be under vacuum (0.001 to 0.005 mbar) and temperature controlled environment at 25C ± 0.001C. The spectrograph will be attached to our upcoming new PRL 2.5m aperture telescope at Gurushikar, Mount Abu, Rajasthan, India. The spectrograph is named PARAS-2 after the successful operation of PARAS (PARAS-1) with our existing 1.2m aperture telescope at Gurushikar, Mount Abu since 2012 summer. The spectrograph (PARAS-2) will be operating in the range of 380nm to 690nm wavelength in a single shot using Grism as a Cross Disperser, R4 Echelle at blaze angle of 76degrees, and pupil diameter of 200 mm. We will use a combination of octagonal and circular fibers along with double scrambler and simultaneous calibration for getting down to the RV precision of 50cm/s or better (< 50cm/s). Minimum 30% time will be reserved for exoplanet work with the spectrograph on the 2.5m telescope when it becomes operational in early 2020. The overall efficiency of the whole spectrograph (Echelle, M1, M2, FM, Grism, Camera lens system, Dewar window) excluding fiber is expected to be 22.5% - 28% and 4% - 8% including optical fiber, telescope and fibertelescope interface losses

Evidence of a Sub-Saturn around EPIC 211945201

We report here strong evidence for a sub-Saturn around EPIC 211945201 and confirm its planetary nature. EPIC 211945201b was found to be a planetary candidate from K2 photometry in Campaigns 5 and 16, transiting a bright star (V_(mag) = 10.15, G0 spectral type) in a 19.492 day orbit. However, the photometric data combined with false positive probability calculations using VESPA was not sufficient to confirm the planetary scenario. Here, we present high-resolution spectroscopic follow up of the target using the PARAS spectrograph (19 radial velocity observations) over a time baseline of 420 days. We conclusively rule out the possibility of an eclipsing binary system and confirm the 2σ detection of a sub-Saturn planet. The confirmed planet has a radius of 6.12 ± 0.1 R⊕, and a mass of 27^(+14)_(-12.6) M⊕. We also place an upper limit on the mass (within the 3σ confidence interval) at 42 M⊕ above the nominal value. This results in the Saturn-like density of 0.65^(+0.34)_(-0.30) g cm^(-3). Based on the mass and radius, we provide a preliminary model-dependent estimate that the heavy element content is 60%–70% of the total mass. This detection is important as it adds to a sparse catalog of confirmed exoplanets with masses between 10 and 70 M⊕ and radii between 4 and 8 R⊕, whose masses and radii are measured to a precision of 50% or better (only 23 including this work)

Discovery of a massive giant planet with extreme density around a sub-giant star TOI-4603

We present the discovery of a transiting massive giant planet around TOI-4603, a sub-giant F-type star from NASA's Transiting Exoplanet Survey Satellite (TESS). The newly discovered planet has a radius of $1.042^{+0.038}_{-0.035}$ $R_{J}$, and an orbital period of $7.24599^{+0.00022}_{-0.00021}$ days. Using radial velocity measurements with the PARAS {and TRES} spectrographs, we determined the planet's mass to be $12.89^{+0.58}_{-0.57}$ $M_{J}$, resulting in a bulk density of $14.1^{+1.7}_{-1.6}$ g ${cm^{-3}}$. This makes it one of the few massive giant planets with extreme density and lies in the transition mass region of massive giant planets and low-mass brown dwarfs, an important addition to the population of less than five objects in this mass range. The eccentricity of $0.325\pm0.020$ and an orbital separation of $0.0888\pm0.0010$ AU from its host star suggest that the planet is likely undergoing high eccentricity tidal (HET) migration. We find a fraction of heavy elements of $0.13^{+0.05}_{-0.06}$ and metal enrichment of the planet ($Z_{P}/Z_{star}$) of $4.2^{+1.6}_{-2.0}$. Detection of such systems will offer us to gain valuable insights into the governing mechanisms of massive planets and improve our understanding of their dominant formation and migration mechanisms.Comment: accepted for publication in A&A Letter