Browsing by Author "Tripathi, Mihir"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Host-star Properties of Hot, Warm, and Cold Jupiters in the Solar Neighborhood from Gaia Data Release 3: Clues to Formation Pathways
    (2024) Banerjee, Bihan; Narang, Mayank; Manoj, P.; Henning, Thomas; Tyagi, Himanshu; Surya, Arun; Nayak, Prasanta K.; Tripathi, Mihir
    Giant planets exhibit diverse orbital properties, hinting at their distinct formation and dynamic histories. In this paper, using Gaia Data Release 3 (DR3), we investigate if and how the orbital properties of Jupiters are linked to their host star properties, particularly their metallicity and age. We obtain metallicities for main-sequence stars of spectral type F, G, and K, hosting hot, warm, and cold Jupiters with varying eccentricities. We compute the velocity dispersions of the host stars of these three groups using kinematic information from Gaia DR3 and obtain average ages using a velocity dispersion-age relation. We find that the host stars of hot Jupiters are relatively metal rich ([Fe/H] = 0.18 +/- 0.13) and young (median age of 3.97 +/- 0.51 Gyr) compared to the host stars of cold Jupiters in nearly circular orbits, which are relatively metal poor (0.03 +/- 0.18) and older (median age of 6.07 +/- 0.79 Gyr). The host stars of cold Jupiters in high-eccentricity orbits, on the other hand, show metallicities similar to those of the hosts of hot Jupiters, but are older, on average (median age of 6.25 +/- 0.92 Gyr). The similarity in metallicity between the hosts of hot Jupiters and the hosts of cold Jupiters in high-eccentricity orbits supports high-eccentricity migration as the potential origin of hot Jupiters, with the latter serving as the progenitors of hot Jupiters. However, the average age difference between them suggests that the older hot Jupiters may have been engulfed by their host star over timescales similar to 6 Gyr. This allows us to estimate the value of stellar tidal quality factor, Q * ' similar to 10 6 +/- 1 .
  • No Thumbnail Available
    Item
    uGMRT Survey of EXoplanets Around M-dwarfs (GS-EXAM): Radio Observations of GJ 1151
    (2024) Narang, Mayank; Puravankara, Manoj; Vedantham, H. K.; Ishwara-Chandra, C. H.; De, Ayanabha; Tyagi, Himanshu; Banerjee, Bihan; Nayak, Prasanta K.; Surya, Arun; Shridharan, B.; Pathak, Vinod C.; Tripathi, Mihir
    Coherent radio emission with properties similar to planetary auroral signals has been reported from GJ 1151, a quiescent, slow-rotating mid-M star, by the LOFAR Two-meter (120-170 MHz) Sky Survey. The observed LOFAR emission is fairly bright at 0.89 mJy with 64% circular polarization, and the emission characteristics are consistent with the interaction between an Earth-sized planet with an orbital period of 1-5 days and the magnetic field of the host star. However, no short-period planet has been detected around GJ 1151. To confirm the reported radio emission caused by the putative planet around GJ 1151 and to investigate the nature of this emission, we carried out upgraded Giant Metrewave Radio Telescope observations of GJ 1151 at 150, 218, and 400 MHz over 33 hr across ten epochs. No emission was detected at any frequency. While at 150 and 218 MHz, nondetection could be due to the low sensitivity of our observations, at 400 MHz, the rms sensitivities achieved were sufficient to detect the emission observed with LOFAR at similar to 20 sigma level. Our findings suggest that the radio emission is highly time variable, likely influenced by the star-planet system's phase and the host star's magnetic field. Additional observations below 170 MHz, at more frequent epochs (as the periodicity of the emission is unknown), especially during periods of high stellar magnetic field strength, are needed to confirm the emission.