The PARAS Telescope

Blog Credit: Trupti Thakur

Image Courtesy: Google

The PARAS Telescope

 

PRL Advanced Radial-velocity Abu-sky Search, abbreviated PARAS, is a ground-based extrasolar planet search device. Based at 1.2m telescope is located at Mt. Abu, India. The project is funded by Physical Research Laboratory, India. The spectrograph works at a resolution of 67000. With the help of simultaneous calibration technique, PARAS has achieved an RV accuracy of 1.3 m/s for bright, quiet, sun-like stars. Thorium-Argon lamp is used for calibration. New calibration techniques are also being explored by the project team. PARAS can detect planet in the habitable zone around M-type stars.

 

With the help of simultaneous calibration technique, PARAS has achieved an RV accuracy of 1.3 m/s for bright, quiet, sun-like stars. Thorium-Argon lamp is used for calibration. New calibration techniques are also being explored by the project team. PARAS can detect planet in the habitable zone around M-type stars.

 

 

PARAS (PRL Advanced Radial velocity Abu Sky Search)

The PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (Prl Advanced Radial-velocity Abu-sky Search), which was commissioned at the Mount Abu 1.2 m telescope in India in 2012. Data obtained as part of the post commissioning tests with PARAS show velocity precision better than 2 m/s over a period of several months to years on bright RV standard stars.

For observations of σ Dra, a 1.7 m/s precision for a period of 2 years, and 3.5m/s on HD55567 have been demonstrated. PARAS is capable of single-shot spectral coverage of 3800–9500 Å at a resolution of ∼67000. The RV results were obtained between 3800 Å and 6900 Å using simultaneous wavelength calibration with a thorium-argon (ThAr) hollow cathode lamp or UAr (Uranium hollow cathode lamps).

The spectrograph is maintained under stable conditions of temperature with a precision of 0.01–0.02° C (rms) at 25.55° C and is enclosed in a vacuum vessel at pressure of 0.1 _ 0.03 mbar. The blaze peak efficiency of the spectrograph between 5000 and 6500 Å, including the detector, is ∼30%; it is ∼25% with the fiber transmission. The total efficiency, including spectrograph, fiber transmission, focal ratio degradation (FRD), and telescope (with 81% reflectivity) is ∼7% in the same wavelength region on a clear night with good seeing conditions. The stable point-spread function (PSF), environmental control, existence of a simultaneous calibration fiber, and availability of observing time make PARAS attractive for a variety of exoplanetary and stellar astrophysics projects.

Light is injected to the spectrograph using combinations of octagonal and circular optical fibers A and B which carries star light and spectral light from spectral lamps for calibration respectively and simultaneously.

Important exoplanet or brown-dwarf discoveries from PARAS:

• “Discovery of an inflated hot Jupiter around a slightly evolved star TOI-1789” 2021arXiv210608660K Submitted to MNRAS.
  The Astronomical Journal, arXiv:2106.08660 Bibcode: 2022MNRAS.509.3339K doi: 10.1093/mnras/stab2970

 

• “TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission”.
  The Astronomical Journal, arXiv:1909.07984 Bibcode: 2020AJ….159..151S doi: 10.3847/1538-3881/ab7245

 

• “Evidence of a Sub-Saturn around Epic 211945201”. The Astronomical Journal.
  The Astronomical Journal, arXiv:1805.03466. Bibcode: Bibcode:2018AJ….156….3C. doi: doi:10.3847/1538-3881/aac436

 

Future:

In view of the upcoming of the PRL 2.5m telescope, which will have an advanced version of PARAS called PARAS-2, original PARAS has been renamed as PARAS-1. PARAS-2 will operate at R~100,000 between 3800 and 6900A and is designed similar to HARPS-N spectrograph. It is expected to have sub-1m/s RV precision.

 

 

 

Blog By: Trupti Thakur