TNT Schedule

Cycle 7 (2019-2020)

ID	Title, PI	Abstract
C07_001	A study of solar-type contact binaries with orbital period less than 0.3 days   PI: Thawicharat Sarotsakulchai (NARIT)	Contact binary system is a late type of close binary stars with short orbital period less than 1 day. They consist of two components with spectral type of F, G or K. Most of them show a strong magnetic activities with spots and light curve variations. In addition, they are commonly found to have an additional companion moving around the central binary. Many statistical studies also show that if contact binaries have short period less than 0.3 days, they are high frequency to have third companions. Most of contact binaries with period between 0.27 to 0.29 days are solar-type components. Therefore, we focus on solar-type contact binaries with high possibility to find their third bodies.
C07_002	Time-series Spectroscopy of the Eclipsing Binary stars with a Pulsating component   PI: Kyeongsoo Hong (KASI)	We will measure the radial velocities and atmospheric parameters for eclipsing binaries (EBs) with a pulsating star to obtain their physical properties. Pulsating EBs that show both eclipses and pulsations are very interesting subjects for investigating the structure and evolution of stars though their binary components, such as δ Sct, γ Dor, red giant, and subdwarf B. The systems can be considered a good astrophysical laboratory for studying mass-transfer processes and binary evolution. We will investigate the evolutionary history of selected EBs by comparing its physical parameters with stellar evolutionary models. For this study, we propose to perform follow-up spectroscopic observations for interesting oscillating EBs with a medium resolution echelle spectrograph (MRES) mounted on the 2.4m Thai National Telescope (TNT) and to study the structure and evolution of stars through asteroseismology and binary properties.
C07_003	Deep spectroscopic survey of chemically peculiar stars in the Orion OB1 association   PI: Eugene Semenko (NARIT)	This observational project is aimed to help the study of the evolution of chemical composition and parameters of young chemically peculiar (CP) stars located in Orion OB1 association. Rich in CP-stars, Orion OB1 is among the closest stellar associations and it has a distinctive and well-determined fragmentation of different parts by age. Recent researches based on GAIA and TESS gave the important insights into stellar evolution in Orion, but the medium to high-resolution spectroscopy even for the stars with V≈8m is still rare. As the spectroscopic observation is vital for determining of membership of the stars and it is the only way to deduce the information about the chemical composition, we decided to compensate this gap with a uniform analysis of spectra obtained with MRES of the 2.4-m telescope of TNO.
C07_004	Search for Raman-Scattered He II Features in Young Planetary Nebulae   PI: Pakakaew Rittipruk (NARIT)	We propose spectroscopy of 13 young planetary nebulae (PNe) in search of Raman-scattered He II features using MRES. Near the hot central white dwarf of a planetary nebula, far UV He II photons are emitted, and subsequently are incident on the circumstellar thick H I region formed through the mass-loss process in the recent asymptotic giant branch stage. They are supposed to be Raman-scattered with H I, leading to formation of Raman-scattered broad emission features in optical region. Thus far these Raman-scattered He II features have been found in only 4 young PNe that are considered to be surrounded by a thick neutral hydrogen region, supported by prominent molecular emission. Our 13 young PNe have similar physical properties with these 4 objects, and in particular, J 900 was observed with the 1.8 m Bohyunsan telescope, in which a strong hint of the presence of Raman He II features was found. Raman-scattered He II features are expected to provide crucially important physical information including kinematics and distribution of the neutral component, which will contribute to our understanding of the evolution from asymptotic giant branch to planetary nebula.
C07_005	Identifying white dwarf-pulsators in interacting binaries   PI: Amornrat Aungwerojwit (Naresuan University)	The study of stellar pulsations, asteroseismology, has the potential to probe the entire interior structure of a star, and very accurate asteroseismological parameter studies have been carried out for single stars. The same method offers an enormous potential to determine the effect that the accretion of mass, angular momentum, and energy has in interacting binaries, and to infer how common envelope evolution affects the stellar structure of the white dwarf that is left behind. However, so far we only know a handful of pulsating white dwarfs in binary stars. Here we propose to use ULTRASPEC on the TNT to increase the number of non-radial pulsators in cataclysmic variables (CVs). This exploratory study is a necessary first step that will be followed by detailed asteroseismological studies once suitable targets have been identified.
C07_006	Evolved planetary systems   PI: Amornrat Aungwerojwit (Naresuan University)	The study of evolved planetary systems is an emerging research field with considerable potential, and our aim is to carry out the first dedicated study of the full range of these systems. This project will significantly contribute to our overall understanding of the formation, architecture, and evolution of planets. We will in particular investigate the tidal disruption of rocky planetesimals and the subsequent formation and evolution of debris discs around white dwarfs through intensive follow-up of WD1145+017, the first white dwarf with detected transits. Our previous TNT observations of this system demonstrate a rapid evolution of the debris field at this white dwarf, providing real-time insight into the physical processes at work. We will also carry out a detailed search for additional systems with photometric transits by obtaining high-time resolution light curves of ~20 white dwarfs with dusty debris discs.
C07_007	Space density of Cataclysmic Variables   PI: Amornrat Aungwerojwit (Naresuan University)	Cataclysmic variables are an excellent benchmark population to test, calibrate, and develop binary population synthesis models. The Sloan Digital Sky Survey (SDSS) produced the deepest and most homogenous CV sample to date, highlighting the importance of the faintest systems to confirm and calibrate models. The spectroscopic completeness of SDSS plummets below i=19.1. However, it is exactly in this range that the composition of the Galactic CV population undergoes a major change. Towards fainter magnitudes the fraction of low-luminosity systems increase and probably dominate the space density of CVs. We propose here to extend the depth of the SDSS CV sample by obtaining TNT observations of faint CV candidates in the SDSS footprint and to measure their orbital periods with the ultimate goal of establishing a statistically representative sample which can be used to test and further develop the theory of compact binary evolution
C07_008	Rapid Multimessenger Observations of Compact Binary Mergers related Optical Transient   PI: Kanthanakorn Noysena (ARTEMIS-IRAP)	The detection of gravitational waves(GW) from LIGO and Virgo has open new era for multimessenger observation with the coincident detection between GW event and gamma-ray burst detection(GRB). The GW150914 is the first GW event detectected by LIGO/Virgo which is the merger between a compact binary mass predicted as a binary black hole merger. Significant detection was a binary neutron star merger which provided the GW, GRB, other electromagnetic(EM) waves including optical transient (OT). The GW170817 was detected with the localization 28 sq. deg of 90% credible region within a luminosity distance of 40 Mpc and GRB 170817A was reported detection by Fermi-GBM at 1.7 s after the GW coalescence. The hypothesis of a neutron star merger has provided the first direct evidence of a link between the GW merger and the short GRB, and variety of EM spectrum. The combination of EM and GW data offers the new and unique opportunity to study the last stages of binary compact systems, their hosts and their contribution to the enrichment of their environment, the processes at play during and immediately after the merger, to measure independently some physical and cosmological constants, and to test General Relativity in the strong field regime. The MRES and ULTRASPEC cameras at Thai National Observatory(TNO) have the appropriate set of characteristics for the detection and follow-up of these sources, Thanks to their fast response and sensitivity that enables the detection of the associated burst and afterglow. We propose to use MRES and ULTRASPEC in Fast Time Response mode whenever one of these instruments are mounted on the telescope and significant visible burst available.
C07_009	Investigation of circumbinary planets and accretion disk formation in three polar CVs   PI: Kittipong Wangnok (Suranaree University of Technology)	Cataclysmic Variables (CVs) are a short-period binary system that consists of a primary white dwarf and the secondary companion stars. Both stars are close to each other causing the secondary star to overflow its Roche lobe and transfers its mass and forms an accretion disk around the white dwarf. The magnetic CVs or Polars consist of a white dwarf with strong magnetic field of 10–60 MG and a main-sequence red dwarf. In such system, the magnetic field of the white dwarf is capable of locking the system into a synchronous rotation and preventing an accretion disk to form around the white dwarf. We propose to observe three polar CVs: UZ For, DP Leo and HU Aqr using 2.4m Thai National Telescope. Since the discovery of possible planets orbiting the three systems, UZ For, DP Leo and HU Aqr pose an enigma of being binaries with violent behaviour, yet able to host circumbinary planets. With this proposal, we aim to study the presence of circumbinary planets in these binaries through light travel time effect. Since the eclipse timing variation may also be caused by the Applegate mechanism, we will perform detailed modeling of the light curves to investigate how the accretion disk formation affects the long-term evolution of planets formed in these binaries. We will obtain the light curves of the three stars using ULTRASPEC in various filters. We will use sigmoid function to determine the eclipse timing of the ingress and the egress during the eclipse, while Gaussian Process will be used for eclipse profile modeling. Moreover, precise stellar and binary parameters will be obtained using Wilson-Devinney code
C07_010	Prominences and their connection to the circumstellar material formation in white dwarf main-sequence binaries   PI: Puji Irawati (NARIT)	Prominences are arcs of gas, held above the surface of the Sun by a strong magnetic field. These atmospheric features are also observed in other stars, such as in close binaries. In white dwarf binaries, evidence of slingshot prominences has been recorded spectroscopically, but the limited time resolution, compared to their rapid evolution makes them hard to study in detail. We have found what we believe to be signature of the circumstellar materials (formed by the materials ejected in the prominences) in a white dwarf / M dwarf binary star through persistent dips in flux caused by obscuration of the white dwarf in the binary system SDSS J1021+1744. This feature was first detected in 2014 (TNO-Cycle 1), but similar feature was again observed during the regular monitoring of WDMS binaries in Cycle 6. Previous observations show that these photometric signatures can lasts for 18 months. Therefore, we propose to do an extensive follow-up of this system during Cycle 7 to investigate whether there is any repeating dip pattern which may indicate a periodicity or orbit of the circumstellar materials in SDSS J1021+1744.
C07_011	A test for the single degenerate channel towards type Ia supernovae   PI: Puji Irawati (NARIT)	The progenitors of type Ia supernovae are close binaries containing white dwarfs. Of crucial importance to the evolution of these systems is how much material the white dwarf can stably accrete and grow in mass. This occurs during the super-soft source (SSS) phase. The short duration of this phase means that only a handful of SSS is known. Far more can be learned from the underlying SSS progenitor population of close white dwarf plus F,G,K type binaries. Using the GALEX and LAMOST surveys we have now identified the first large sample of F,G,K stars with significant UV excesses typical of white dwarfs. Follow-up observations at the TNT using MRES and several other telescopes have led us to the discovery of 24 binaries among our sample displaying significant radial velocity variations (published in 2017). Further search using data from LAMOST, RAVE, and TGAS has brought our samples to ~60 systems. Here we apply for 4 nights of observations at the TNT with MRES to measure the orbital periods of 6 candidates among the brightest WD+FGK binaries in our samples.
C07_012	Sub-milliarcsecond resolution measurements with ULTRASPEC through asteroid occultations   PI: Tarek Hassan (DESY)	This proposal is to use the diffraction pattern in the shadow generated by asteroid occultations of stars to measure their angular size at the sub-milliarcsecond (mas) level. When a solar-system object, such as an asteroid, occults a star, it provides a powerful tool for studying both the occulting object and the occulted star. Occultations of stars by asteroids have generally been used to extract information of the shape and structure of asteroids, by detecting the time of occultation at different points along the shadow path over the Earth. The diffraction pattern fitting technique has been successfully exploited with lunar occultation measurements to measure stellar angular diameters down to the ~1 mas level. As proven by recent measurements with VERITAS, the resolution attained by the Moon occultation technique can be improved by an order of magnitude if the occulted object is an asteroid (generally main belt). By using ULTRASPec, diffraction patterns from asteroid occultations can be measured with unprecedented sensitivity. The detection of each proposed occultation would not only allow to constrain the size and shape of the occulting asteroid, they will also allow the measurement of the occulted star down to the ~100 microarcsecond scale. With the signal to noise ratio given by ULTRASPec, we would prove that this technique is able to directly measure star diameters with relative errors at the 3% level, required as input for exoplanet diameter measurements.
C07_013	SLODAR for AO at TNT   PI: Somsawat Rattanasoon (NARIT)	The slope detection and ranging (SLODAR) technique measures atmospheric turbulence strength as a function of altitude for support of adaptive optics for astronomy. The instruments provide real-time measurements of the atmospheric turbulence strength, altitude and velocity. The TNT is the same size as the Isaac Newton Telescope (INT) on La Palma. A SLODAR instrument has previously been operated on the INT with a dichroic. The dichroic is not necessary on TNT so the full sensitivity range of the detector will be used. The TNT SLODAR had 18x18 subaperture, a pupil diameter at lenslet array of 9mm. and WFS image scale 0.387 arcsec/pixel. Durham team and TNT telescope operators had installed SLODAR at TNT on March 2019 and tested the whole system during the late observing season.
C07_014	Atmospheric Study of HAT-P-33b   PI: Sutthawee Yodmongkol (Suranaree University of Technology)	HAT-P-33b is an exoplanet orbiting around its host star, GSC2461-00988 (Hartman et al., 2011). From Morgan et al. (2019), HAT-P-33b is ranked 30 in atmospheric detectability metric. Moreover, there is no report of HAT-P-33b atmosphere using the transit method and there is no detailed study of this planet after its discovery paper. Therefore, we plan to use the TNT to study of HAT-P-33b with more filter to allow us to obtain detailed physical and also its atmospheric parameters.
C07_015	Circumbinary planet around NSVS 14256825   PI: Pranita Sappankum (Chiang Mai University)	The eclipsing binary (O-C) can be used to detect circumbinary planets, including those around NSVS 14256825 However, due to high uncertainty in the data, there are more three proposed third-body model for this system, including one-planet model and two-planet model. In this proposal, we would like to observe NSVS 14256825 with ULTRASPEC at TNT in order to obtain precise eclipse timing to confirm the presence of (a) circumbinary planet(s).
C07_016	Follow-up the transit of HAT-P-48b using 2.4m Thai National Telescope   PI: Patcharawee Munsaket (Suranaree University of Technology)	HAT-P-48b is an exoplanet super-Neptune with 0.168 Jupiter's mass. It was discovered in 2016. This exoplanet orbit around HAT-P-48 with an orbital period of 4.40865 days (Bakos et al. 2016). The host star mass is 1.009 of Sun's mass. From the discovery paper, we used the mid-transit time to calculate the ingress and egress time of observation on 18 December 2018. We found that the ingress and egress time of HAT-P-48b is differed by about 15 mins from discovered paper. Therefore, we would like to follow-up the transit of HAT-P-48b using the 2.4m Thai National Telescope to confirming the transit timing of HAT-P-48b.
C07_017	Red-dwarf Contact Binaries Searching   PI: Liying Zhu (Yunnan Observatories, Chinese Academy of Sciences)
	Transmission spectroscopy of exoplanets   PI: Supachai Awiphan (NARIT)	Todate, more than 4,000 planets, ranging in size from Earth to larger than Jupiter, have been confirmed by various methods, including over 2,300 by Kepler using the transit method (Morton et al. 2016). In addition to the discovery of new exoplanets, the characterization of planetary interiors and atmospheres is a rapidly developing area. One method that is used to study planetary atmospheres is transmission spectroscopy, which measures the variation of transit depth with wavelength (Seager & Deming 2010). From the transmission spectroscopy technique, the absorption spectrum and the composition of the planetary atmosphere can be deduced. This method has been applied to several transiting exoplanets. During 2013-16 observational seasons, we used the TNT to perform transmission spectroscopy of a hot-Neptune, GJ3470b, which provide a low mean molecular weight (1.08\pm0.20) with high particle abundance at high altitude atmosphere (Awiphan et al. 2016). In this proposal, we plan to use the TNT with ULTRASPEC and the Thai Robotic Telescopes Network (TRTN) to perform transmission spectroscopy observation of exoplanets in order to provide a better understanding of exoplanet atmosphere and statistic of planetary atmosphere. Between 2016-2019, we follow seven transiting exoplanets to obtain their transmission spectra. In 2019-2020 observational season, we select new set of targets based on our metric-based target selection approach for selecting exoplanets for their atmospheric studies (Morgan et al. 2019).
C07_019	Follow-up TESS exoplanet candidates   PI: Supachai Awiphan (NARIT)	TESS is an ongoing all-sky survey which aims to discover thousands of new transiting exoplanets that orbit stars about 10 times closer and 100 times brighter than those found by Kepler. To date, 29 new interesting transiting planets have been discovered and at least 1100 TESS Object of Interest (TOI) identified after observing the Southern hemisphere in the first half of its 2-year mission alone. Here, we propose to use TNT/ULTRASPEC to conduct efficient follow-up photometric observations to validate the planetary nature and improve the ephemeris of several interesting TOIs in the Northern hemisphere. This proposal is a natural continuation of our previous follow-up efforts to validate K2 planet candidates with TNT/Ultraspec (de Leon, in prep.).
C07_020	Testing L(H-Beta)-Sigma Relation as Distance Indicators for HII galaxies and dE with blue cores   PI: Krittapas Chanchaiworawit (NARIT, U of Florida) (NARIT, FAU, U of Florida)	HII regions are established with L(H-Beta)-Sigma relation that can be used for deriving distances if the velocity dispersion (sigma) can be measured. HII galaxies and blue star-forming cores of some dwarf ellipticals are exhibiting similar emission features and morphology to the well-established HII regions. Thus, we proposed to observe 6 extragalactic HII regions (HII galaxies and dE's blue-cores) with MRES to test their feasibility of being utilized as distance indicator and their second parameters associated with this L(H-Beta)-Sigma relation, such as age, metallicity, dust extinction, and size. The high spectral resolution of MRES will allow us to precisely measure the velocity dispersion of the Balmer and metal emission lines, and the shape of their continua, crucial for studying their chemical abundances and testing their L(H-Beta)-Sigma relation against the previously study of the Galactic HII regions. With 6 nights or 60 hours of the requested observation 3, we may achieve a new interesting, reliable distance indicator that can be used for observation cosmology in the near future.
C07_021	Reverberation Mapping of the bright AGN in MACS J1149   PI: Krittapas Chanchaiworawit (NARIT, U of Florida)	We propose to study the variation of an intermediate redshift Active Galactic Nucleus (AGN) in the rich and massive cluster, MACS J1149. The bright AGN will be monitored in optical wavelengths via broad-band filters of ULTRASEPC imager at the Thai National Telescope every 4 days for the period of 100 days. By tracking the variation of flux across all optical bands, we can perform Reverberation Mapping (RM) of this AGN (i.e., tracing the time lags of variation in one band to the next). We will find the time lags from shorter to longer wavelengths using the Discrete Correlation Functions. The time lags represent the distances to specific regions of the central Super-Massive Blackhole's accretion disk. Our goal is to test the recent findings that the size of the accretion disk of the AGNs in the local Universe seem to be ~3 times larger than theorized by the mainstreamed "thin disk model". With the total requested time of 50 hours (2 hours/epoch x 25 epochs), we will not only be able to obtain high signal-to-noise photometry of the AGN in each night, but also gain the extremely deep optical-band images (detection limit of g'~26 mag) of the cluster (MACS J1149) and its surrounding region as well. This proposed observation will provide a unique RM study of a higher redshift AGN and also a photometric sample of galaxies and potential AGNs too.
C07_022	Long-term monitor of the long-period redback pulsar J2129-0429   PI: Siraprapa Sanpa-arsa (NARIT)	PSR J2129-0429 is a “redback” pulsar binary that belongs to the more general class of “Spiders”, in which a pulsar gradually ablates a low-mass companion orbiting at close distance. Some redbacks called transitional millisecond pulsars have recently been found to occupy a key stage of binary evolution marking the transition from active accretion in a low-mass X-ray binary to a rotation-powered pulsar with an evolved companion. J2129 is the first and only formally identified Spider in which small secular optical changes have been detected so far and, while it is not a proper transitional system, it might give us very important clues about the evolution of these systems. We propose to initiate a bi-annual monitoring campaign in order to 1) track the future behaviour of this system and 2) shed light on the physical mechanism responsible for these secular changes.
C07_023	A Follow Up Spectroscopic Survey of oEA stars discovered by TESS mission.   PI: David Mkrtichian (NARIT)	Using the data from the first year of operation of TESS space telescope, PI of the proposal discovered 35 new oscillating Algol-type (oEA) stars in the southern hemisphere what is approximately the half of previously known class of oEA stars. We already did the period search analysis of the light curves of these new TESS pulsators and found their complex oscillation spectra. Our proposal is aimed to carry out the medium resolution spectroscopic survey and get accurate orbits, stellar parameters and chemical composition of part of new TESS oEA stars visible from the TNO latitudes.
C07_024	Spectroscopic studies of Young stellar objects   PI: Tirthendu Sinha (ARIES)	With this proposal, we are requesting for 8 hours on fibre-fed Medium Resolution Spectrograph (MRES) mounted on the 2.4m Thai National Telescope (TNT) to carry out optical spectroscopic study of selected Young Stellar Objects (YSO) . With MRES we can trace different emission and absorption lines like Hα, Hβ, HeI, OI, NaI, [SII] etc. This informations will be useful to calculate the accretion rate, outflow density and temperature, stellar winds, etc of these YSOs. We have been photometrically monitoring YSOs in different star-forming regions in optical (BVI) wavebands also. This along with spectroscopic data will be used to confine the nature and cause of variability in these YSOs. We can also correlate the amplitude of variation with accretion rates to understand the individual contribution of different lines in stellar variability.
C07_025	Searching for circumbinary bodies in eclipsing binary systems   PI: Ronnakrit Rattanamala (Chiang Mai University)	Eclipsing binaries are common in our universe. In order to understand their physical parameters and evolution, their light curves should be obtained. However, in some systems, the presence of third bodies in the systems might cause the change in their orbital period from the light travel time effect. The change can be detected via the O-C diagram and the residual of O-C diagram. This third body can be brown dwarf, red dwarf or planet. The aims of this study is to search for circumbinary bodies in four eclipsing binary systems. Due to the short in their orbital period (P < 0.3 days), high-time resolution photometry with ULTRASPEC on the TNT are required.
C07_026	Extended [OIII] emission as a tracer of AGN outflows from narrow-line Seyfert I   PI: Wiphu Rujopakarn (Chulalongkorn University)	Feedback from active galactic nuclei (AGN) is now a standard ingredient in galaxy formation models, yet the direct characterization of such feedback, e.g., AGN-driven outflows, is scarce. We propose to observe a sample of narrow-line Seyfert I (NLSy I) galaxies at z = 0.3 using deep narrow-band imaging to search for the redshifted, extended OIII emission in the host galaxies and search for potential signatures of galaxy wide outflows. As a pilot study, we propose to observe at least six NLSy I galaxies and constrain the geometry and size of the extended narrow-line region. The narrow-band images will complement deep imaging data from the Subaru Hyper-Suprime Cam (HSC) imaging survey which is currently used to study the host morphology and to estimate stellar masses. Given that the host galaxies are extended out to ~10 kpc we can directly compare the ionized OIII emission with the stellar component. This is a resubmission of a Cycle 6 proposal, which was approved for 3 nights on the TNO (distributed over 4 days), but no exposure was taken due to cloud and high humidity.
C07_027	Search for and investigate progenitors of luminous red novae   PI: Shengbang Qian (Yunnan Observatories, Chinese Academy of Sciences)	Luminous red novae (LRNe) are a rare type of stellar outbursts that are typically more luminous than most classical novae. Investigations have shown that they are produced from the merging of evolved deep-contact binary stars. In this project, we have selected some evolved binary stars based on the LAMOST data. Then we intend to monitor some of them photometrically with the 2.4-m TNT telescope. Based on those observations, basically physical parameters could be determined by using the W-D method and their geometrical structures and evolutionary states will be understood. Our scientific purposes are to search for extremely deep-contact binaries and then investigate the merging of deep-contact binaries and the origin of luminous red novae outbursts. These results will shed light to the formation and evolution of the progenitors of γ-ray bursts. The investigations will also help to explain several astrophysical phenomena (e.g. the origin of magnetic fields of massive stars and the formations of stellar massive black holes).
C07_028	Spectroscopic studies of FUors/EXors using MRES with Thai National Telescope   PI: Arpan Ghosh (ARIES)	We propose to carry out medium-resolution spectroscopic study of five FUors/EXors present in the Orion and Cygnus regions using Medium Resolution Spectrograph (MRES) mounted on 2.4m Thai National Telescope (TNT). FUors/EXors sources usually show outburst events (ΔV~3-5 mag) due to the episodic accretion of matter from the circumstellar disc onto the proto-star. Medium resolution spectroscopic data of multiple epochs are crucial in understanding the physical process involved in the evolution of the proto-planetary disc of these comparatively less know sources. For example, the Hα line that originate from the accretion column and jets will help us to estimate the accretion rate and fluctuations in them help us to accurately constrain the different trigger mechanisms of outbursts. Optically thin forbidden emission lines of O[I], Fe[II] will help us to understand the mass loss during different phases, outflow temperature and density and outflow nature. Equivalent width ratios of the absorption lines Fe[I], Fe[II], etc will help in the determination of surface gravity and effective temperature and their relation to magnitude variations. Recently such medium resolution study has been performed by Takagi et al in 2018. Given the spectral resolution (R~15000) and the broad spectral coverage (400-850 nm) MRES is ideal instrument to fulfill our science goal.
C07_029	Photometric Investigation of Variable Stars in Open Clusters NGC 1817 and NGC 1245   PI: Nareemas Chehlaeh (Prince of Songkla University)	Star clusters are crucial for an understanding of the formation and the evolution of both single stars and binaries. Open clusters with variable members also provide a comparative tool to study stellar structure and pulsation in great detail based on the implications of a common origin and formation of their stellar members. This research will study the population of variable stars (including also eclipsing binaries) in the well-known open cluster NGC1817 with a rich population of Delta Scuti stars and NGC 1245. We aim to perform a detailed and more accurate analysis of the pulsational properties of the pulsating stars by combining the old and the new data sets. The physical parameters including magnitudes, periods, and the masses of the binary systems in the star cluster will also be analyzed.
C07_030	Absolute parameters of spectroscopic binaries TW Cas and IM Aur   PI: Pranita Sappankum (Chiang Mai University)	Two Spectroscopic binary system of Algol-type were selected in this programmed. TW Cas and IM Aur have orbital period 1.4283 and 1.2473 days, respectively. Since their discoveries, there is no spectroscopic studies in this two systems. The spectroscopy observations on these systems will precisely constraint physical parameters of each component in the system. TW Cas and IM Aur show the cyclic variation in their O-C curves. The variation might be caused by the presence of a third body in the system. In order to precisely constraint the parameters of its primary component, secondary component and third body, we want to observe TW Cas and IM Aur with MRES on TNT.
C07_031	Searching for extrasolar planets orbiting white-dwarf binaries   PI: Shengbang Qian (Yunnan Observatories, Chinese Academy of Sciences)	One of the most interesting things that we have learnt about extrasolar planets is that they can exist almost anywhere. Investigations have shown that white-dwarf binaries could be planetary hosting stars. In this project, we intend to monitor some white-dwarf eclipsing binary photometrically with the 2.4-m TNT telescope. Based on those observations, mid-eclipse times of the sample stars will be determined. Our scienti¡c purposes are to search for and to investigate circumbinary planets orbiting white-dwarf binary stars by analyzing the light travel[1]time effect. These results will shed light to the formation and evolution of circumbinary planets, and will help to understand the ultimate fate of planets and the late evolutionary stage of binary stars. Our data can also be used to study magnetic activity of the red-dwarf component stars that can provide some information on CV evolution and outburst.