Search

The success of helioseismology is due to its capability of measuring p-mode oscillations in the Sun. This allows us to extract informations on the internal structure and rotation of the Sun from the surface to the core. Similarly, asteroseismology is the study of the internal structure of the stars as derived from stellar oscillations. In this review we highlight the progress in the observational asteroseismology, including some basic theoretical aspects. In particular, we discuss our contributions to asteroseismology through the study of chemically peculiar stars under the "Nainital-Cape Survey" project being conducted at ARIES, Nainital since 1999. This survey aims to detect new rapidly-pulsating Ap (roAp) stars in the northern hemisphere. We also discuss the contribution of ARIES towards the asteroseismic study of the compact pulsating variables. We comment on the future prospects of our project in the light of the new optical 3.6-m telescope to be install at Devasthal (ARIES). Finally, we present a preliminary optical design of the high-speed imaging photometers for this telescope., published in Journal of Astrophysics & Astronomy. arXiv admin note: text overlap with arXiv:1405.3145, arXiv:1212.5084, arXiv:1205.6407, arXiv:1212.2384, arXiv:1109.3455, arXiv:1104.5191, arXiv:1102.1884, arXiv:1310.0696, arXiv:1310.2266 by other authors

The basic physical parameters of a poorly studied open cluster NGC 110 and an unstudied open cluster DOLIDZE 14 are estimated in the present study using the archival PPMXL and WISE catalogues. The radius of both the clusters are estimated by fitting the modified King's empirical model on their stellar density profiles. The other basic parameters of the clusters such as distance, reddening, and age are obtained by visual fitting of the Marigo's solar metallicity isochrone on their IR colour-magnitude diagrams (CMDs). The mean-proper motion of the clusters are estimated through the individual proper motion of probable members identified through the dynamical and statistical methods. The archival catalogues (JHKW1W2) are constructed for both the clusters by compiling the extracted data from the PPMXL and WISE catalogues. The various colour-excesses, such as E(J-H), E(H-K) and E(W1-W2), are estimated using the best fit theoretical isochrone on the (J-H)-H, (H-K)-H and (W1-W2)-H CMDs, respectively. The ratios of various infrared colours of the clusters are obtained through their two-colour diagrams. We also identify the most probable members in these clusters by estimating spatial, kinematic and spatio-kinematic probabilities of stars within the cluster. A correlation between the E(H-K) and E(W1-W2) is also established., 23 pages, 7figures

We present photometric analysis of the two W UMa type binaries identified in the field of distant open star cluster NGC6866. Although these systems, namely ID487 and ID494, were reported in the Joshi et al. (2012), but a detailed study of these stars has not been carried out earlier. The orbital periods of these stars are found to be 0.415110+/-0.000001 day and 0.366709+/-0.000004 day, respectively. Based on the photometric and infrared colours, we find their respective spectral types as K0 and K3. The photometric light variations of both the stars show O'Connell effect which could be explained by employing a dark spot on the secondary components. The V and I bands light curves are analyzed using the Wilson-Devinney (WD) code and relations given by Gazeas (2009) which yield radii and mass of the primary and secondary components of the star ID487 as R1 = 1.24+/-0.01 Rsun, R2 = 1.11+/-0.02 Rsun, and M1 = 1.24+/-0.02 Msun, M2 = 0.96+/-0.05 Msun, and for the star ID494 as R1 = 1.22+/-0.02 Rsun, R2 = 0.81+/-0.01 Rsun, and M1 = 1.20+/-0.06 Msun, M2 = 0.47+/-0.01 Msun., Comment: 12 pages, 7 figures, 2016, RAA, 16, 11

We present a complete spatial and dynamical study of the poorly populated stellar system ESO65SC03. The radial distribution of the system gives a core and cluster radii of 1.10+/-0.63 arcmin and 5.36+/-0.24 arcmin, respectively. The surface number density profile (SNDP) does not show any clear enhancement of the surface stellar number density between the stars of the system and the field regions. We derive the optimum isochrone solution for a particular grid size in the colour-magnitude diagram (CMD) using the statistical cleaning procedure. Using the statistically cleaned CMDs, we find the distance modulus, (m-M)_0, and reddening, E({B-V}), of the system to be 11.8+/-0.2 mag and 0.45 mag, respectively. The mean proper motion of this system is -5.37+/-0.81 mas/yr and 0.31+/-0.40 in RA and DEC directions, respectively. The mean proper motion of this system is found to be almost similar to the field region. The mass function for the brighter stars is found to be too high for the system to be an open cluster. These combined results place constraints on whether stellar system ESO65SC03 is a possible open star cluster remnant (POCR) or an Asterism. Our understanding is that the ESO65SC03 is in a stage of POCR by loosing their main sequence stars in the dynamic evolution processes., Comment: 10 pages, 9 figures, accepted for publication in PASA

The chapter deals with the pattern of changes in the diversity components of lichen communities around a paper mill in northeastern Indian region. Four indices (Shannon index, Pielou index, Margalef index, and Simpson index) are calculated for the seventeen sites situated within a radius of 25 km from the mill. The indices are studied vis-a-vis the distance (from the mill) and elevation. Positive correlation is found between number of species and distance, while a negative correlation is found between numbers of species and the elevation. Changes in the pattern of indices are seen along three distance categories; 20 km. As expected, the dominance index increased (54 %) and the diversity, richness, and evenness index decreased near the mill; maximum decrease being for Shannon index (>14 %) of diversity. It is observed that neither of the indices showed significant correlation with the altitude or distance. The Shannon, Margalef, and Simpson index showed significant correlation with the number of species. The effect of stress on biodiversity is depicted with the help of changes in the shapes of Odum’s model of ‘concave’ curve. It is observed from the graphical representation of the ‘number of species’ and ‘number of individual per species’ that the nearness to the mill converted the ‘concave’ hollow curve into a flattened one and ultimately into a ‘convex’ curve.

The “Nainital-Cape Survey” program for searching photometric variability in chemically peculiar (CP) stars was initiated in 1997 at ARIES, Nainital. We present here the results obtained to date. The Am stars HD 98851, HD 102480, HD 13079 and HD 113878 were discovered to exhibit δ Scuti type variability. Photometric variability was also discovered in HD 13038, for which the type of peculiarity and variability is not fully explained. The null results of this survey are also presented and discussed.

We report our analysis of the stability of pulsation periods in the DAV star (pulsating hydrogen atmosphere white dwarf) ZZ Ceti, also called R548. On the basis of observations that span 31 years, we conclude that the period 213.13 s observed in ZZ Ceti drifts at a rate dP/dt 5 (5.5 plus or minus 1.9) x 10(exp -15) ss(sup -1), after correcting for proper motion. Our results are consistent with previous P values for this mode and an improvement over them because of the larger time base. The characteristic stability timescale implied for the pulsation period is |P||P(raised dot)|greater than or equal to 1.2 Gyr, comparable to the theoretical cooling timescale for the star. Our current stability limit for the period 213.13 s is only slightly less than the present measurement for another DAV, G117-B15A, for the period 215.2 s, establishing this mode in ZZ Ceti as the second most stable optical clock known, comparable to atomic clocks and more stable than most pulsars. Constraining the cooling rate of ZZ Ceti aids theoretical evolutionary models and white dwarf cosmochronology. The drift rate of this clock is small enough that we can set interesting limits on reflex motion due to planetary companions.

Heterodermia flabellata (Fée) D. D. Awasthi was found as a new lichen record in Jeju Island of South Korea in 2012. A detailed taxonomic description and comments are provided for the taxa. An updated key for all recorded species of Heterodermia from South Korea is given.

The study introduces the genus Mycobilimbia, from South Korea. M. philippina is reported here as being new to the country. Characteristic features of the species are crustose thallus, globose apothecia, K-proper exciple and hypothecium, Biatora-type asci, 3-septate fusiform ascospores, and a lack of secondary compounds.

Chapter 1. Boundary Behavior of Univalent Harmonic Mappings: A Survey of Recent Boundary Behavior Results of Univalent Harmonic Mappings.- Chapter 2. Harmonic Univalent Mappings and Minimal Graphs.- Chapter 3. Minimal Surfaces over the Slanted Half Planes, Vertical Strips and Single Slit.- Chapter 4. A Survey on Special Classes of Bazilevic Functions and Related Function Classes.- Chapter 5. Uniqueness of Entire Functions Sharing Certain Values with Derivatives.- Chapter 6. Differential Superordinations and Sandwich-Type Results.- Chapter 7. Starlikeness and Convexity of Certain Integral Transforms by using Duality Technique.- Chapter 8. Enestrom-Kakeya Theorem and Some of Its Generalizations.- Chapter 9. Starlikeness, Convexity and Close-to-Convexity of Harmonic Mappings.- Chapter 10. On Generalized p-Valent Non-Bazilevic Type Functions.- Chapter 11. Integral Mean Estimates for a Polynomial with Restricted Zeros.- Chapter 12. Uniqueness Results for Meromorphic Functions Concerning Small Functions.- Chapter 13. Maxima Polynomial Ranges for a Domain of Intersection of Two Circular Disks.

Usnea Adans. is a somewhat rare lichen in South Korea, and, in nearly two decades, no detailed taxonomic or revisionary study has been conducted. This study was based on the specimens deposited in the lichen herbarium at the Korean Lichen Research Institute, and the samples were identified using information obtained from recent literature. In this study, a total of eight species of Usnea, including one new record, Usnea hakonensis Asahina, are documented. Detailed descriptions of each species with their morphological, anatomical, and chemical characteristics are provided. A key to all known Usnea species in South Korea is also presented.

We present UBVRI photometry of stars in the field of the intermediate-age open cluster NGC 559. By determining the stellar membership probabilities derived through a photometric and kinematic study of the cluster, we identify the 22 most probable cluster members. These are used to obtain robust cluster parameters. The mean proper motion of the cluster is \mu_x = -3.29+/-0.35, \mu_y = -1.24+/-0.28 mas/yr. The radial distribution of the stellar surface density gives a cluster radius of 4'.5+/-0'.2 (3.2+/-0.2 pc). By fitting solar metallicity stellar isochrones to the colour-colour and colour-magnitude diagrams, we find a uniform cluster reddening of E(B-V) = 0.82+/-0.02. The cluster has an age of 224+/-25 Myr and is at a distance of 2.43+/-0.23 kpc. From the optical and near-infrared two-colour diagrams, we obtain colour excesses in the direction of the cluster E(V-K) = 2.14+/-0.02, E(J-K) = 0.37+/-0.01, and E(B-V)= 0.76+/-0.04. A total-to-selective extinction of Rv=3.5+/-0.1 is found in the direction of the cluster which is marginally higher than the normal value. We derive the luminosity function and the mass function for the cluster main sequence. The mass function slope is found to be -2.1+/-0.3. We find evidence of mass segregation in this dynamically relaxed cluster., Comment: Accepted for publication in MNRAS, 13 pages, 10 figures, 11 tables

Hypotrachyna (Vainio) Hale is a somewhat rare lichen genus found on the Korean Peninsula. Since it was first recorded more than two decades ago, no detailed taxonomic or revisionary study of the genus has been conducted. Thus, the present study was conducted to carry out a detailed taxonomic and revisionary study of Hypotrachyna in South Korea. This study was based on specimens deposited in the Korean Lichen Research Institute (KoLRI). Detailed taxonomic studies and a literature review confirmed the presence of seven species of Hypotrachyna from South Korea, including one new record, Hypotrachyna nodakensis (Asahina) Hale. Descriptions of each species with their morphological, anatomical and chemical characters together with a key to all known Hypotrachyna species are presented.

The Nainital-Cape survey is a dedicated ongoing survey programme to search for and study pulsational variability in chemically peculiar (CP) stars to understand their internal structure and evolution. The main aims of this survey are to find new pulsating Ap and Am stars in the northern and southern hemisphere and to perform asteroseismic studies of these new pulsators. The survey is conducted using high-speed photometry. The candidate stars were selected on the basis of having Stromgren photometric indices similar to those of known pulsating CP stars. Over the last decade a total of 337 candidate pulsating CP stars were observed for the Nainital-Cape survey, making it one of the longest ground-based surveys for pulsation in CP stars in terms of time span and sample size. The previous papers of this series presented seven new pulsating variables and 229 null results. In this paper we present the light curves, frequency spectra and the various astrophysical parameters of the 108 additional CP stars observed since the last reported results. We have also tabulated the basic physical parameters of the known roAp stars. As part of establishing the detection limits in the Nainital-Cape survey, we investigated the scintillation noise level at the two observing sites used in this survey, Sutherland and Nainital, by comparing the combined frequency spectra stars observed from each location. Our analysis shows that both the sites permit the detection of variations on the order of 0.6 milli-magnitude (mmag) in the frequency range 1-4 mHz, with Sutherland being marginally better, on average.

The present account briefly describes two crustose lichen species new to South Korea. Detailed taxonomic descriptions of Leiorreuma exaltatum and Trapelia coarctata, supported by distribution, ecology and illustrations, are provided. Both species were collected from warm-temperate, humid forests of Jeju Island.

We report the discovery of large scale diffuse non-thermal radio emission in PLCK G287.0+32.9, an exceptionally hot (T ~ 13 keV), massive and luminous galaxy cluster, strongly detected by the PLANCK satellite in a recent, all-sky blind search for new clusters through Sunyaev-Zel'dovich effect. Giant Metrewave Radio telescope 150 MHz and Very Large Array 1.4 GHz radio data reveal a pair of giant (>1 Mpc) "arc" shaped peripheral radio-relics (signatures of shock waves) of unprecedented scale (linear separation ~4.4 Mpc at redshift 0.39), located at distances from the cluster center which are about 0.7 and 1.3 of the cluster's virial radius. Another possible giant relic and a radio-halo is detected closer to the cluster center. These relic sources are unique "signposts" of extremely energetic mergers and shocks (both ongoing and past), that are assembling and heating up this very massive galaxy cluster. They are also a probe of the filamentary cosmic-web structure beyond the cluster virial radius. Optical imaging with the IUCAA 2 meter telescope and XMM-Newton X-ray data confirm a very rich galaxy cluster with a morphologically disturbed core region, suggesting a dynamically perturbed merging system., This version matches with the published version in Astrophysical Journal Letters

Here we present the report on the “Nainital–Cape survey” research project aiming to search for and study the pulsational variability of main-sequence chemically peculiar (CP) stars. For this study, the time-series photometric observations of the sample stars were carried out at the 1.04 m ARIES telescope (India), while the high-resolution spectroscopic and spectro-polarimetric observations were carried out at the the 6.0 m Russian telescope. Under this project, we have recently found clear evidence of photometric variability in the Am star HD 73045, which is likely to be pulsating in nature with a period of about 36 min, hence adding a new member to the family of the δ Scuti pulsating variables that have peculiar abundances.

The Nainital-Cape survey is a dedicated research programme to search and study pulsational variability in chemically peculiar stars in the Northern Hemisphere. The aim of the survey is to search such chemically peculiar stars which are pulsationally unstable. The observations of the sample stars were carried out in high-speed photometric mode using a three-channel fast photometer attached to the 1.04-m Sampurnanand telescope at ARIES. The new photometric observations confirmed that the pulsational period of star HD25515 is 2.78-hrs. The repeated time-series observations of HD113878 and HD118660 revealed that previously known frequencies are indeed present in the new data sets. We have estimated the distances, absolute magnitudes, effective temperatures and luminosities of these stars. Their positions in the H-R diagram indicate that HD25515 and HD118660 lie near the main-sequence while HD113878 is an evolved star. We also present a catalogue of 61 stars classified as null results, along with the corresponding 87 frequency spectra taken over the time scale 2002-2008. A statistical analysis of these null results shows, by comparison with past data, that the power of the noise in the light curves has slightly increased during the last few years., 24 pages, 12 figures, accepted for publication in Astronomy and Astrophysics

International audience; Context: L-type ultra-cool dwarfs and brown dwarfs have cloudy atmospheres that could host weather-like phenomena. The detection of photometric or spectral variability would provide insight into unresolved atmospheric heterogeneities, such as holes in a global cloud deck. Indeed, a number of ultra-cool dwarfs have been reported to vary. Additional time-resolved spectral observations of brown dwarfs offer the opportunity for further constraining and characterising atmospheric variability. Aims: It has been proposed that growth of heterogeneities in the global cloud deck may account for the L- to T-type transition when brown dwarf photospheres evolve from cloudy to clear conditions. Such a mechanism is compatible with variability. We searched for variability in the spectra of five L6 to T6 brown dwarfs to test this hypothesis. Methods: We obtained spectroscopic time series using the near-infrared spectrographs ISAAC on VLT-ANTU, over 0.99-1.13 μm, and SpeX on the Infrared Telescope Facility for two of our targets in the J, H, and K bands. We searched for statistically variable lines and for a correlation between those. Results: High spectral-frequency variations are seen in some objects, but these detections are marginal and need to be confirmed. We find no evidence of large-amplitude variations in spectral morphology and we place firm upper limits of 2 to 3% on broad-band variability, depending on the targets and wavelengths, on the time scale of a few hours. In contrast to the rest of the sample, the T2 transition brown dwarf SDSS J1254-0122 shows numerous variable features, but a secure variability diagnosis would require further observations. Conclusions: Assuming that any variability arises from the rotation of patterns of large-scale clear and cloudy regions across the surface, we find that the typical physical scale of cloud-cover disruption should be smaller than 5-8% of the disk area for four of our targets, using simplistic heterogeneous atmospheric models. The possible variations seen in SDSS J1254-0122 are not strong enough to allow us to confirm the cloud-breaking hypothesis. Based on observations obtained at the European Observatory, Paranal, Chile, under programme 71.C-0559.

Taking a clue from their sharp-edged (strip-like) morphology observed in several cases, a new mechanism is proposed for the formation of the emission gaps seen between the radio lobes of many powerful extragalactic double radio sources. Canonical understanding of the radio gaps invokes either blocking of the back-flowing lobe plasma by the denser interstellar medium (ISM) of the host galaxy, or "squeezing" of the radio bridge in the middle through buoyancy force exerted by either the ISM or the surrounding intra-cluster medium (ICM). These pictures encounter difficulties in explaining situations where the sharp-edged radio gaps associated with non-cluster radio galaxies have widths running into several tens (even hundreds) of kiloparsecs. More particularly, the required dense high-pressure ISM/ICM is likely to be lacking at least in the case of high-redshift radio galaxies. We propose here that radio emission gaps in at least such cases could arise from a dynamical interaction between the powerful thermal wind outflowing from the active galactic nucleus and the back-flowing synchrotron plasma in the two radio lobes, which occurs once the rapidly advancing jets have crossed out of the wind zone into the intergalactic medium. A simple analytical scheme is presented to explore the plausibility of the side-ways confinement of the thermal wind by the radio lobe pair, which would "freeze" pancake shaped conduits in the space, along which the hot, metal enriched wind from the AGN can escape (roughly orthogonal to the radio axis). Some other possible consequences of this scenario are pointed out., Comment: 10 pages, 3 figures [one .jpg], official version published in MNRAS

We report the discovery of a very unusual, highly asymmetric radio galaxy whose radio jet, the largest yet detected, emits strongly polarized synchrotron radiation and can be traced all the way from the galactic nucleus to the hot spot located ~440 kpc away. This jet emanates from an extremely massive black hole (>10^9 solar mass) and forms a strikingly compact radio lobe. No radio lobe is detected on the side of the counterjet, even though it is similar to the main jet in brightness up to a scale of tens of kiloparsecs. Thus, contrary to the nearly universal trend, the brightness asymmetry in this radio galaxy increases with distance from the nucleus. With several unusual properties, including a predominantly toroidal magnetic field, this Fanaroff-Riley type II megajet is an exceptionally useful laboratory for testing the role of magnetic field in jet stabilization and radio lobe formation., Published in The Astrophysical Journal Letters, Volume 670, L85-L88, 2007

To search photometric variability in chemically peculiar A type stars in the northern hemisphere. High-speed photometric observations of Ap and Am star candidates have been carried out from ARIES (Manora Peak, Nainital) using a three-channel fast photometer attached to the ARIES 104-cm Sampurnanand telescope. This paper presents three new variables: HD 113878, HD 118660 and HD 207561. During the time span of the survey (1999 December to 2004 January) pulsations of the $\delta$ Sct type were also found for the two evolved Am stars HD 102480 and HD 98851, as reported in Joshi et al. (2002, 2003). Additionally, we present 140 null results of the survey for this time span. The star HD 113878 pulsates with a period of 2.31 hr, which is typical of $\delta$ Sct stars. HD 118660 exhibits multi-periodic variability with a prominent period of nearly 1 hr. These periods need to be investigated and make HD 118660 a particularly interesting target for further observations. For HD 207561, a star classified as Am, a probable pulsation with a period of 6 min was found in the light curves obtained on two consecutive nights. Both HD 102480 and HD 98851 exhibit unusual alternating high and low amplitude maxima, with a period ratio of 2:1. The analysis of the null results confirms the photometric quality of the Nainital, Comment: 14 pages, 13 figures, Accepted for publication in A&A

HR 1217 is one of the best-studied rapidly oscillating Ap (roAp) stars, with a frequency spectrum of alternating even- and odd-� modes that are distorted by the presence of a strong, global magnetic field. Several recent theoretical studies have found that within the observable

HR1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of nonradial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of 33.3 μHz and 34.6 μHz, with a sixth mode at a problematic spacing of 50.0 μHz (which equals 1.5 × 33.3 μHz) to the highfrequency side. Asymptotic pulsation theory allowed for a frequency spacing of 34 μHz, but hipparcos observations rule out such a spacing. Theoretical calculations of magnetoacoustic modes in Ap stars by Cunha (2001) predicted that there should be a previously undetected mode 34 μHz higher than the main group, with a smaller spacing between it and the highest one. The 20th extended coverage campaign of the Whole Earth Telescope (XCov20) has discovered this frequency as predicted by Cunha (2001). Amplitude modulation of several of the pulsation modes between the 1986 and 2000 data sets has also been discovered, while important parameters for modelling the geometry of the pulsation modes have been shown to be unchanged. With stringent selection of the best data from the WET network the amplitude spectrum shows highest peaks at only 50 μmag and formal errors on the determined amplitudes are 14 μmag. Some lessons for future use of WET for the highest precision photometry on bright stars are discussed.

We present results from a multisite (‘Whole Earth Telescope’) photometric campaign on PG 1336−018, the close eclipsing binary system containing a pulsating subdwarf B (sdB) star. The main part of the campaign (1999 April) resulted in ~172 h of observations, representing a coverage of about 47 per cent, and additional data were obtained outside the core campaign. Periodogram analysis shows that the light variations are dominated by three frequencies near 5757, 5585 and 5369 μHz (~174, 179 and 186s, respectively), although many frequencies are present, particularly in the range 5000–6000 μHz (~200–170 s). We identify, with some confidence, 28 frequencies down to a semi-amplitude of 0.0005 in fractional intensity (equivalent to about 0.5 mmag). It is clear that the pulsation frequencies of PG 1336−018 have changed substantially since the 1996 discovery observations were made, and that amplitude changes occur, at least in the dominant three frequencies, on relatively short time-scales (of the order of a day). On the assumption that the pulsating star is phase-locked in the binary system, we have searched for rotational splitting of frequencies near the orbital and half of the orbital period, but the results are confused by aliasing at those frequencies (due to the data gaps caused by the eclipses). A preliminary model qualitatively matches the distribution of frequencies in PG 1336−018, with some good individual correspondences, but cannot be considered adequate because geometric cancellation should hide some of the modes which are apparently detected. Analysis of the pulsations during eclipse recovers three of the strongest modes, but the limited eclipse data – which can, at best, be only about 9 per cent of the total – do not allow mode identification at this stage. Simulations indicate that an overall coverage of about 80 per cent would be required for this to be viable. An attempt was made to determine phase shifts in the pulsation frequencies as a way of directly measuring the size of the binary orbit, but the uncertainties in the method are comparable to the light travel time across the orbit (probably less than a second).

In the genus Xanthoparmelia, species boundaries are based on morphological and chemical features such as the presence and/or absence of secondary metabolites, diagnostic reproductive structures, isidia morphology, and color of lower surface. Two new species of Xanthoparmelia are described from South Korea, X. kolriana with cylindrical isidia containing atranorin and salazinic acid as major components in the medulla together with cortical usnic acid, while X. volcanicola is characterised by a red coloured medulla, and subglobose isidia. The characteristics of Xanthoparmelia species and their distribution in South Korea are outlined and an identification key given. Additionally, we used ITS ribosomal DNA sequences to assess the monophyly of Xanthoparmelia species from South Korea. Our results reveal that traditionally circumscribed species were not recovered as monophyletic clades. Further, we here show that ITS is insufficient to estimate a well-supported phylogenetic hypothesis, but suggests that traditional taxonomy may not reflect natural groups. This communication provides an important framework for future studies assessing species boundaries in Xanthoparmelia species in South Korea.

The present study explores the lichen flora in traditional homegardens in Panchgram area of Barak valley, southern Assam. Homegardens are important component of rural socioeconomy in northeast India and are preserved through traditional wisdom of local communities. Homegardens mimic forest structures and harbour rich diversity of cultivated as well as natural floral composition helping in conservation of important lichens of the region which hold in it tremendous potential of ethnolichenological use for present and future. The present work enumerates 68 lichens representing 22 genera and 11 families found in randomly selected homegardens in an area of about 28 km2 around Panchgram. Out of these 68 lichens, 10 exhibit foliose growth form and remaining 58 lichens exhibit crustose growth form. Graphidaceae is the dominant family representing 22 species followed by Pyrenulaceae (17 species) and Arthoniaceae (10 species). Pyrenula (17 species) is the dominant genus in the region followed by Arthonia with 8 species and Phaeographis and Graphis with 7 species each. The common homegarden lichens Parmotrema tinctorium, Parmotrema saccatilobum and Graphis scripta which are found during the study have ethnolichenological uses recorded in various literature studies. Ethnolichenological studies are very scarce in northeast India. Owing to rich ethnic and floristic diversity in the region, present study suggests the role of homegardens in conserving lichens which might have unexplored traditional use by indigenous communities and needs proper documentation.

We present the analysis of 65 hours of high speed photometric observations of HD 12098 taken from State Observatory, Naini Tal and Gurushikhar Observatory, Mt.Abu on sixteen nights spanning from November 1999 to November 2000. HD 12098 is the first rapidly oscillating Ap star discovered from the `Naini Tal-Cape survey for northern hemisphere roAp stars'. It is the 32nd in the complete list. HD 12098 exhibits one predominant mode of oscillation at nu_1 = 2.1738 mHz. The second-most significant frequency in our data is at nu_2 = 2.1641 mHz with a 1 cycle/day alias ambiguity. We argue that nu_2 is a rotational sidelobe of nu_1, rather than an independent pulsation mode. Evidence for the presence of two other frequencies at 2.1807 and 2.3056 mHz is also presented., 6 pages, 4 eps figures, A&A style, Accepted for publication in A&A

Homegardens create a forest like multistorey structure with different vertical and horizontal layers and it has a characteristic pattern of species diversity. The present paper throws light on the importance of homegardens as a significant lichen refuge. The study explored a lichen diversity of 44 species with a representation of 17 genera and 9 families. Graphidaceae is the dominant family followed by Pyrenulaceae and Arthoniaceae. Graphis and Pyrenula are found to be the dominant genera representing about 40% of total species richness. It is observed that the homegardens are shelters to about 15% of lichens, which have restricted distribution (endemic) in the eastern Himalayan region. The traditional wisdom along with ecological knowledge of the local people in maintaining homegardens in northeastern region seems to be helping in conserving the genetic heritage of wild lichen species of the eastern Himalayan region. This becomes more important in the wake of wanton destruction of forests and hence lichens growing there.

The present work deals with the application of Shannon Index to explore the spatial extent and pattern of air pollution around a paper mill. The index measures the change in lichen diversity in response to the polluted environment around a paper mill in Assam, North-East India. The Shannon index around the paper mill ranged from 0.56 at 2.4 km to 1.20 at 13.7 km with a mean value of 0.92. About 47% of the sites have Shannon index value below mean value. The index does not show significant correlation with the distance from the paper mill. The values are plotted with the help of kriging interpolation and an air quality model is prepared. The dark shades in the model indicate highly polluted regions while the brighter shades indicate less polluted to clean areas. Higher polluted areas with low values of Shannon index are the regions around and nearer to the paper mill, town area, and around stone crusher units. It is concluded that the Shannon index is a potential indicator to measure the effect of air pollution and can be used to delineate the pollution zones around any industrial area.

The lichen biodiversity pattern across elevational gradient in Pindari Glacier valley was studied, using different diversity indices. The study was done across elevational gradient ranging from 1760m to 3660m consisting of three different biomes; temperate, alpine, and temperate-alpine transition. A total of 84 species of lichens were found consisting of three major growth forms and three habitat preferences. Shannon, Pielou, and Margalef indices showed similar trends, while the Simpson index showed a slightly different trend. Except Simpson index all other indices exhibit a positive trend with the altitude. In case of growth forms, except foliose growth form all other are showing a positive trend with increasing altitude. It is also observed that the corticolous lichen dominates (~90%) in temperate and temperate-alpine transition, and saxicolous lichens dominate (98%) in Alpine zone. Although relational study between elevational gradient with higher plants are done, but with lichens it is one of the first type in western Himalayas.