B. G. Anandarao

The PRL Stabilized High-Resolution Echelle Fiber-fed Spectrograph: Instrument Description and First Radial Velocity Results

We present spectrograph design details and initial radial velocity results from the PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (PARAS), which has recently been commissioned at the Mount Abu 1.2 m telescope in India. Data obtained as part of the postcommissioning tests with PARAS show velocity precision better than 2 m s-1 over a period of several months on bright RV standard stars. For observations of σ Dra, we report 1.7 m s-1 precision for a period of 7 months, and for HD 9407, we report 2.1 m s-1 over a period of 2 months. PARAS is capable of single-shot spectral coverage of 3800-9500 A at a resolution of ~67,000. The RV results were obtained between 3800 and 6900 A using simultaneous wavelength calibration with a thorium-argon (ThAr) hollow cathode lamp. 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 A, 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. Future plans include testing of octagonal fibers for further scrambling of light and extensive calibration over the entire wavelength range up to 9500 A using thorium-neon (ThNe) or uranium-neon (UNe) spectral lamps. Thus, we demonstrate how such highly stabilized instruments, even on small aperture telescopes, can contribute significantly to the ongoing radial velocity searches for low-mass planets around bright stars.

Detection of knots and jets in IRAS 06061+2151

We report detection of a Young Stellar Object with an evidence for an outflow in the form of knots in the molecular hydrogen emission line (2.121µm) towards the massive star forming region IRAS 06061+2151. Near-infrared images reveal IRAS 06061+2151 to be a cluster of at least five sources, four of which seem to be early B type young stellar objects, in a region of 12 arcsecs surrounded by a nebulosity. The presence of the knots that are probably similar to the HH objects in the optical wavelengths, suggests emerging jets from one of the cluster members. These jets appear to excite a pair of knot-like objects (Knot-NW and Knot-SE) and extend over a projected size of 0.5pc. The driving source for the jets is traced back to a member of the cluster whose position in the H-Ks/J-H color-color diagram indicates that it is a Class I type pre-mainsequence star. We also obtained K band spectra of the brightest source in the cluster and of the nearby nebular matter. The spectra show molecular hydrogen emission lines but do not show Br line (2.167µm). These spectra suggest that the excitation of the molecular hydrogen lines is probably due to a mild shock.

SS 433: results of a recent multiwavelength campaign

We conducted a multiwavelength campaign in 2002 September-October, to observe SS 433. We used the Giant Meter Radio Telescope for radio observations, the Physical Research Laboratory Infrared Telescope at Mt Abu for infrared (IR), the ARIES telescope at Nainital for optical photometry, the telescope at the Vainu Bappu observatory for spectral measurements and the Rossi X-ray Timing Explorer for X-ray observations. We find sharp variations in intensity on time-scales of a few minutes in the X-ray, IR and radio wavelengths. Differential photometry in the IR observations clearly indicates significant intrinsic variations on short time-scales of minutes throughout the campaign. Combining the results for these wavelengths, we find a signature of delay of about two days between the IR and radio signals. The X-ray spectrum yielded double Fe line profiles which corresponded to red and blue components of the relativistic jet. We also present the broad-band spectrum averaged over the campaign duration.

Determination of mass and orbital parameters of a low-mass star HD 213597B

HD 213597 is an eclipsing binary system which was detected by the STEREO spacecraft and was speculated to host a low-mass stellar companion. We used high-resolution spectroscopy with the 10-m Hobby–Eberly Telescope and the 1.2-m telescope in Mount Abu for radial velocity (RV) measurements of this source. We performed aperture photometry for this star on the STEREO archival data and thereby confirm the transit signature. We also did followup ground-based photometry with a 10-inch telescope from Mt Abu. The spectroscopic RV semi-amplitude of the primary (33.39 km s −1 ) indicates that the secondary is an M dwarf making the system a short period F+M eclipsing binary. These RVs along with the inclination derived from our combined photometric analysis (i = 84. ◦ 9), enable us to estimate the mass –

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 (

Precision velocimetry planet hunting with PARAS: current performance and lessons to inform future extreme precision radial velocity instruments

V_{\rm mag}=10.15

PHOTOMETRIC EVIDENCE OF BULLETS IN SS433 JETS

, 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-

Masses and Radii of Four Very Low-mass Stars in F+M Eclipsing Binary Systems

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Detection of a very low mass star in an Eclipsing Binary system

detection of a sub-Saturn planet. The confirmed planet has a radius of 6.12

Near-infrared photometry and radio continuum study of the massive star-forming regions IRAS 21413+5442 and IRAS 21407+5441

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