Optical spectroscopy of comets

Comets are pristine remnants of the Solar system, composed of dust and ice. They remain inactive and undetectable for most of their orbit due to low temperatures. However, as they approach the Sun, volatile materials sublimate, expelling dust and creating a visible coma. Spectroscopic observations of comets help the simultaneous study of both the gas emissions and reflected sunlight from dust particles. By implementing a long slit, the spatial variations in molecular emissions can be analysed to be further used for other computations. Additionally, spatial information aids in extracting the characteristic profile of the Af(rho) parameter, revealing insights into the behaviour of dust emissions. A sufficiently long slit would prove advantageous in extracting information about the emissions occurring at different parts of the coma or even the tail. We can gain an overall comprehensive understanding of a comet's chemical composition and dust emission by constructively utilising low-resolution spectroscopy with the help of a long slit.Comment: 10 pages, 8 figures, accepted for publication in Bulletin de la Soci\'et\'e Royale des Sciences de Li\`ege (2023

Mass function and dynamical study of the open clusters Berkeley 24 and Czernik 27

We present a $UBVI$ photometric study of the open clusters Berkeley 24 (Be 24) and Czernik 27 (Cz 27). The radii of the clusters are determined as 2\farcm7 and 2\farcm3 for Be 24 and Cz 27, respectively. We use the Gaia Data Release 2 (GDR2) catalogue to estimate the mean proper motions for the clusters. We found the mean proper motion of Be 24 as $0.35\pm0.06$ mas yr$^{-1}$ and $1.20\pm0.08$ mas yr$^{-1}$ in right ascension and declination for Be 24 and $-0.52\pm0.05$ mas yr$^{-1}$ and $-1.30\pm0.05$ mas yr$^{-1}$ for Cz 27. We used probable cluster members selected from proper motion data for the estimation of fundamental parameters. We infer reddenings $E(B-V)$ = $0.45\pm0.05$ mag and $0.15\pm0.05$ mag for the two clusters. Analysis of extinction curves towards the two clusters show that both have normal interstellar extinction laws in the optical as well as in the near-IR band. From the ultraviolet excess measurement, we derive metallicities of [Fe/H]= $-0.025\pm0.01$ dex and $-0.042\pm0.01$ dex for the clusters Be 24 and Cz 27, respectively. The distances, as determined from main sequence fitting, are $4.4\pm0.5$ kpc and $5.6\pm0.2$ kpc. The comparison of observed CMDs with $Z=0.01$ isochrones, leads to an age of $2.0\pm0.2$ Gyr and $0.6\pm0.1$ Gyr for Be 24 and Cz 27, respectively. In addition to this, we have also studied the mass function and dynamical state of these two clusters for the first time using probable cluster members. The mass function is derived after including the corrections for data incompleteness and field star contamination. Our analysis shows that both clusters are now dynamically relaxedComment: 16 pages including 8 tables. 22 figures. Accepted by MNRA

Effect of a plant versus animal based diet on lipid profile of yoga practicing medical students: a pilot study

Background: Foods play an important role in human health. An excess accumulation of cholesterol in the body is one of the main causes of cardio vascular disease, hypertension, type 2 diabetes mellitus, dyslipidemia and mortality. In the interests of food safety and public health, plants and their compounds are now re-emerging as an alternative approach to treat gastrointestinal diseases. The present study was designed to discuss changes in blood cholesterol levels after the consumption of animal based (non vegetarian) and plant based (vegetarian) food on yoga practising medical students.Methods: Of 81 subjects, a total of 60 subjects within the age group 18 to 22 years were selected for the study and were divided into two groups, non-vegetarian diet group (group A; n=30) and vegetarian diet group (group B; n=30). Subjects in the group A were given a non vegetarian diet and group B a vegetarian diet for a period of 10 days. Assessments were done at baseline and after 10 days.Results: There were no statistically significant changes seen in the lipid profiles of group B and group A after the application of a paired t test. In this study the mean value of total cholesterol, serum triglyceride, serum LDL and serum VLDL were found to be slightly higher in vegetarian group than the non-vegetarian group. Mean value of serum HDL was found to be higher in non-vegetarian group than the vegetarian.Conclusions: The present study concludes that there are more changes in the pre and post lipid profile assessments of the vegetarian group in comparison to the non-vegetarian group

Optical polarimetry of the blazar CGRaBS~ J0211+1051 from MIRO

We report the detection of high polarization in the first detailed optical linear polarization measurements on the BL Lac object CGRaBS J0211+1051, which flared in $\gamma$-rays on 2011 January 23 as reported by Fermi. The observations were made during 2011 January 30 - February 3 using photo-polarimeter mounted at the 1.2m telescope of Mt Abu InfraRed Observatory(MIRO). The CGRaBS J0211+1051 was detected to have $\sim21.05\pm 0.41$ degree of polarization (DP) with steady position angle (PA) at 43$^\circ$ on 2011 January 30. During Jan 31 and Feb 1, while polarization shows some variation, position angle remains steady for the night. Several olarization flashes occurred during February 2 and 3 resulting in changes in the DP by more than 4% at short time scales ($\sim$ 17 to 45 mins). A mild increase in the linear polarization with frequency is noticed during the nights of February 2 & 3. The source exhibited significant inter-night variations in the degree of polarization (changed by about 2 to 9%) and position angle (changed by 2 to 22$^\circ$) during the five nights of observations. The intra-night activity shown by the source appears to be related to turbulence in the relativistic jet. Sudden change in the PA accompanied by a rise in the DP could be indicative of the fresh injection of electrons in the jet. The detection of high and variable degree of polarization categorizes the source as low energy peaked blazar.Comment: 14-pages including 3-figure