1,201 research outputs found

    Photospheric properties and fundamental parameters of M dwarfs

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    M dwarfs are an important source of information when studying and probing the lower end of the Hertzsprung-Russell (HR) diagram, down to the hydrogen-burning limit. Being the most numerous and oldest stars in the galaxy, they carry fundamental information on its chemical history. The presence of molecules in their atmospheres, along with various condensed species, complicates our understanding of their physical properties and thus makes the determination of their fundamental stellar parameters more challenging and difficult. The aim of this study is to perform a detailed spectroscopic analysis of the high-resolution H-band spectra of M dwarfs in order to determine their fundamental stellar parameters and to validate atmospheric models. The present study will also help us to understand various processes, including dust formation and depletion of metals onto dust grains in M dwarf atmospheres. The high spectral resolution also provides a unique opportunity to constrain other chemical and physical processes that occur in a cool atmosphere The high-resolution APOGEE spectra of M dwarfs, covering the entire H-band, provide a unique opportunity to measure their fundamental parameters. We have performed a detailed spectral synthesis by comparing these high-resolution H-band spectra to that of the most recent BT-settl model and have obtained fundamental parameters such as effective temperature, surface gravity, and metallicity (Teff, log g and [Fe/H]) respectively.Comment: 15 pages, 10 figures, accepted for publication in A&

    The Effective temperature scale of M dwarfs from spectral synthesis

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    We present a comparison of low-resolution spectra of 60 stars covering the whole M-dwarf sequence. Using the most recent PHOENIX BT-Settl stellar model atmospheres (see paper by F. Allard, in this book) we do a first quantitative compari- son to our observed spectra in the wavelength range 550-950 nm. We perform a first confrontation between models and observations and we assign an effective tempera- tures to the observed M-dwarfs. Teff-spectral type relations are then compared with the published ones. This comparison also aims at improving the models' opacities.Comment: To be published in the on-line version of the Proceedings of Cool Stars 16 (ASP Conference Series) New version with bibliography correcte

    Progress in Modeling Very Low Mass Stars, Brown Dwarfs, and Planetary Mass Objects

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    We review recent advancements in modeling the stellar to substellar transition. The revised molecular opacities, solar oxygen abundances and cloud models allow to reproduce the photometric and spectroscopic properties of this transition to a degree never achieved before, but problems remain in the important M-L transition characteristic of the effective temperature range of characterizable exoplanets. We discuss of the validity of these classical models. We also present new preliminary global Radiation HydroDynamical M dwarfs simulations.Comment: Submitted to Mem. S. A. It. Supp

    Ageing effect on grooming activity in langur male bands (Semnopithecus entellus) in and around Jodhpur (India)

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    The study is based on grooming activity in different age class members of Semnopithecus entellus entellus all-male bands (AMB). All males seem to reach a peak in grooming frequency during and immediately following puberty and it is suggested that this peak corresponds to a period of establishing coalition bonds. High grooming rates may also be found in young adults who are actively and assertively challenging higher-ranking individuals. Finally, some old males exhibit paternalistic behavior toward young (generally pre-pubertal) males, which includes grooming, co-feeding and active defense by the older male. These observations are consistent with the hypothesis than grooming is an instrumental behaviour analogous to human gift exchange, which can be “used” by an individual for his ultimate benefit

    Attention-based Multi-modal Sentiment Analysis and Emotion Detection in Conversation using RNN

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    The availability of an enormous quantity of multimodal data and its widespread applications, automatic sentiment analysis and emotion classification in the conversation has become an interesting research topic among the research community. The interlocutor state, context state between the neighboring utterances and multimodal fusion play an important role in multimodal sentiment analysis and emotion detection in conversation. In this article, the recurrent neural network (RNN) based method is developed to capture the interlocutor state and contextual state between the utterances. The pair-wise attention mechanism is used to understand the relationship between the modalities and their importance before fusion. First, two-two combinations of modalities are fused at a time and finally, all the modalities are fused to form the trimodal representation feature vector. The experiments are conducted on three standard datasets such as IEMOCAP, CMU-MOSEI, and CMU-MOSI. The proposed model is evaluated using two metrics such as accuracy and F1-Score and the results demonstrate that the proposed model performs better than the standard baselines

    Ecology and conservation of golden jackal (Canis aureus) in Jodhpur, Rajasthan

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    At north-west of India there is dry, semi arid region called as The Great Indian Thar desert. It lies between 24o and 35o 5’ N latitude and 70o 7’ and 76o 2’ E. Mammals of Thar desert includes the wolf (Canis lupus), the stripped hyaena (Hyaena hyaena), golden Jackal (Canis aureus), the Indian desert fox (Vulpes v. pusilla), wild bore (Susscrofaspc.), black buck (Antilo pecervicapra), blue bull (Boselaphus tragocamelus), chinkara (Gazella benneti), Hanuman langur (Semenopithecus entellus) etc. Golden Jackal is unique in distribution, occurrence, and survives at different environmental conditions in India including the hot desert. Present study has been carried out at Phitkasni village, situated south-east of Jodhpur city. Large population of golden Jackal has observed and data of their homerange, territory, inter-specific relation, conflict with human and mortality has been studied. It is concluded that regular monitoring and proper conservation management is needed in this area so Jackal and other carnivore like wolf, desert fox and hyena can also be conserved

    Detection and characterisation of two VLM binaries: LP 1033-31 and LP 877-72

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    Using the high-resolution near-infrared adaptive optics imaging from the NaCo instrument at the Very Large Telescope, we report the discovery of a new binary companion to the M-dwarf LP 1033-31 and also confirm the binarity of LP 877-72. We have characterised both the stellar systems and estimated the properties of their individual components. We have found that LP 1033-31 AB with the spectral type of M4.5+M4.5 has a projected separation of 6.7±\pm1.3 AU. Whereas with the spectral type of M1+M4, the projected separation of LP 877-72 AB is estimated to be 45.8±\pm0.3 AU. The binary companions of LP 1033-31 AB are found to have similar masses, radii, effective temperatures, and log gg with the estimated values of 0.20±\pm0.04 M⊙\rm{M}_{\odot}, 0.22±\pm0.03 R⊙\rm{R}_{\odot}, 3200 K, 5.06±\pm0.04. However, the primary of LP 877-72 AB is found to be twice as massive as the secondary with the derived mass of 0.520±\pm0.006 M⊙\rm{M}_{\odot}. The radius and log gg for the primary of LP 877-72 AB are found to be 1.8 and 0.95 times that of the secondary component with the estimated values of 0.492±\pm0.011 R⊙\rm{R}_{\odot} and 4.768±\pm0.005, respectively. With an effective temperature of 3750±\pm15 K, the primary of LP 877-72 AB is also estimated to be ∌\sim400 K hotter than the secondary component. We have also estimated the orbital period of LP 1033-31 and LP 877-72 to be ∌\sim28 and ∌\sim349 yr, respectively. The binding energies for both systems are found to be >\gt1043^{43} erg, which signifies both systems are stable.Comment: 14 pages, 6 figures, accepted for publication in MNRA

    Study of the impact of tourists and local visitors / feeders on free-ranging Hanuman langur population in and around Jodhpur, Rajasthan (India)

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    The Jodhpur city of Rajasthan has many tourist places where Hanuman langurs habitually feed on the food given by the visitors to them. The interactions were studied between Hanuman langurs and the visitors in and around Jodhpur by means of interviewing the visitors and direct observations of the behaviour of Hanuman langurs and visitors. Most (82.2%) of the observed interactions involved the presence of food; only in 17.8% of the interactions we observed langurs threatening or chasing the visitors. Some differences, however, emerged between what the visitors reported in the interviews and what we observed. Most respondents (76.1%) reported in the interviews that hostile interactions were started by monkeys, whereas analysis of the direct interactions showed that 47.3% of such interactions were initiated by visitors and only 39.6% by Hanuman langurs. Moreover, 83.9% of the visitors affirm them to feed Hanuman langurs, while 70.2% of them report having seen other visitors feeding them. On the basis of the above results, it would be beneficial to establish an educational program, providing information about the behaviour of Hanuman langurs and the consequences that feeding them could have on their behaviour and on their interactions with visitors

    Latitudinal Pigmentation Variation Contradicts Ultraviolet Radiation Exposure: A Case Study in Tropical Indian Drosophila melanogaster

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    The effects of ultraviolet radiation (UV) on the animal body have been reported in many studies, and melanin has emerged as a protective mechanism. In smaller insects such as Drosophila, replicated patterns of geographical variation in pigmentation have been observed on multiple continents. Such patterns are particularly pronounced on the Indian subcontinent where several species show a parallel cline in pigmentation traits. However, the potential role of UV exposure in generating the observed patterns of pigmentation variation has not been addressed. Here, we examine the association between UV intensity and body pigmentation in D. melanogaster natural populations collected along the latitudinal gradient of the Indian subcontinent. A strong negative relationship was observed between UV intensity and body pigmentation. This analysis clearly indicates that, in the sampled populations, pigmentation variation is independent of UV exposure and related selection pressures. Patterns of pigmentation in natural populations from the Indian subcontinent are better predicted by latitude itself and temperature-related climatic variables
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