| ID | Title, PI | Abstract |
|
TNTC011_001 |
Optical Counterparts and follow up Gravitational Wave Events during the fourth observing run of LIGO and Virgo PI: Dr. Kanthanakorn Noysena (NARIT) |
The initial identification of gravitational waves (GWs) through GW150914 provided undeniable evidence for the existence of both gravitational waves and the phenomenon of binary black hole (BBH) mergers. The detection of the binary neutron star (BNS) merger GW170817, associated with both a short Gamma-Ray Burst (sGRB) and a Kilonova (KN) led to the beginning of the multi-messenger era of astrophysics. GW170817 answered many questions, but still left many open and gave rise to a large number of new ones. Therefore, more counterparts and follow-up GW events will need to be observed in the fourth scientific observing run (O4) of LIGO and Virgo. The 2.4-meter Thai national telescope (TNT) can play an important role in the field by following-up optical transients discovered by wide-field telescopes, such as the Thai Robotic Telescope (TRT), the Gravitational-Wave Optical Transient Observer (GOTO), and the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA) in all of which the PI of this proposal is an active member. Here we propose to use TNT for a multi-observatory campaign that will be coordinated with observations from TRT, GOTO, GRANDMA. The trigger for ToO programme will only respond to significant alerts from GWs, sGRBs, and optical transients discovered during the O4 run and will aim at the characterization of the counterparts using multi-band photomety. |
| TNTC011_002 |
Absolute Properties of Eclipsing Binaries with Pulsating Components
PI: Dr. Kyeongsoo Hong |
Eclipsing binaries (EBs) allow for direct and independent determination of the absolute dimensions of each component without any assumptions from time-series photometry and spectroscopy, while pulsating stars are capable of probing their interiors from cores to envelopes and placing rigorous constraints on stellar theory through their pulsation features. Most stars in binary and multiple systems are born almost simultaneously and evolved by interaction between their components. The pulsating variables such as δ Sct and γ Dor stars in such systems are very useful for probing the impacts of mass transfer and tides on stellar evolution and interior structure. Recently, the EB stars with multiple pulsations have increased significantly in number thanks to space missions such as Transiting Exoplanet Survey Satellite (TESS). However, accurate physical properties have been only determined for about 20 pulsating EBs. Therefore, high-resolution spectroscopic observations for these stars are needed. We will investigate the evolutionary history of selected EBs by comparing their physical parameters with stellar models. For this, we propose to perform follow-up spectroscopic observations of interesting oscillating EBs using the 2.4m Thai National Telescope (TNT) with Medium Resolution Echelle Spectrograph (MRES), and to study their structure and evolution through asteroseismology and binary properties. |
| TNTC011_003 |
Observational study on evolution of the ultrashort-period cataclysmic variables
PI: Prof. Shengbang Qian |
In the field of stellar astrophysics, the minimum period cut-off of cataclysmic binaries (CVs) is an unsolved problem. The standard model proposes that the donor will transit from a star to a degenerate brown dwarf after reaching the period minimum. The donor's structure changes, resulting in a reversal in the orbital period evolution's direction. The systems evolving back towards longer periods are referred to as period bouncers. The evolution theory also predicts that about 70% of CVs should be period bouncers. However, until recently, only a few candidate period bouncers were known, posing a serious challenge to the standard model. This also makes the ultrashort-period cataclysmic binaries around the period minimum into the important objects for studying the evolution of CVs. In this project, our scientific purposes are to monitor some eclipsing CVs photometrically with the 2.4-m TNT telescope. Based on those observations, coupled with the historical data, we plan to analyze systematically the law of orbital period changes in these binaries, and search for the potential period bouncers with long-term period increase. In the meantime, systems with secular period decreases will be investigated, and angular momentum loss mechanisms will be discussed. Our data can also be used to study the period changes of candidate bouncers with sub-stellar donors and to test the standard model. These results can enrich our understanding and knowledge of the evolution and outburst of CVs. |
| TNTC011_005 |
Space density of Cataclysmic Variables
PI: Dr. Amornrat Aungwerojwit |
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. |
| TNTC011_006 |
Identifying white dwarf-pulsators in interacting binaries PI: Dr. Amornrat Aungwerojwit |
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. |
| TNTC011_007 |
Evolved planetary systems
PI: Dr. Amornrat Aungwerojwit |
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. In addition in cycle 8-9, we obtained the light curves of two debris disc systems, ZTF J0328–0129, and ZTF J0923+4236 which reveal very diverse behaviour compared to WD 1145+017. We then propose here (a) to obtain intense high-speed follow-up of both systems, during Cycle 10 to characterise in detail the morphology, and temporal variability of the light curves, including (9 nights required), and (b) to carry out a detailed search for additional systems with photometric transits by obtaining high-time resolution light curves of ~3-4 (out of ~20) white dwarfs with dusty debris discs (9 nights required). |
| TNTC011_008 |
Long-term monitoring of the long-period redback pulsar PSR J2129-0429
PI: Dr. Siraprapa Sanpa-arsa |
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 a 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 significant clues about the evolution of these systems. Further investigation is warranted as there appears to be a relative flux change in the z band of TNT data from 2017 to 2021. We propose to initiate a bi-annual monitoring campaign in order to 1) track the future behavior of this system and 2) shed light on the physical mechanism responsible for these secular changes. |
| TNTC011_009 |
Doppler imaging of non-radial pulsations of the fast rotating A-type pulsators in the solar neighborhood. PI: Dr. David Mkrtichian |
The project for the TNT telescope is aimed to detect and study high-degree nonradial pulsations using the Doppler imaging of pulsations in A-type fast rotating pulsators close to the Sun. The survey is ongoing and successful, we plan to get during a winter-spring 2023/24 at TNT+MRES continuous and high-time resolution spectral time series for the new sample of fainter (and more distant) fast-rotating bright A-type stars. The photometric variability of selected targets was detected by us using precise light curves from the TESS space telescope. The spectroscopic series will be analyzed using the 2D DFT analysis of spectral line profiles and identification of modal degree and azimuthal number will be obtained. |
| TNTC011_010 |
Search for the progenitors of the stellar merger
Prof. Liying Zhu |
Stellar mergers are estimated to be common events in the Galaxy. However, those phenomena have not been efficiently probed by the Galactic surveys. Till now, V1309 Sco is the only confirmed non-compact stellar merger, which is identified mainly by its pre-outburst light curve. The modeling of the pre-outburst light curves of V1309 Sco reveals that its progenitor is a low mass ratio contact binary with high fill-out factor. This link opens the window to investigate the stellar merger and the final fate of the contact binaries. In order to search for such progenitors of the stellar merger, we have investigated the LAMOST data and monitored a group of contact binaries for years photometrically and derived dozens of candidates of stellar merger progenitor with obvious period change. However, most of them are partial eclipsing binaries and show strong asymmetric light curves probably due to magnetic activities, which prevent us derive the reliable mass ratio based on the light curves only. So we need to combine the radial velocity curves to obtain the precise mass ratio. Furthermore, the third body orbiting around the binary may play an import role to the merger of the central binary. In this project, we apply the observational time of TNT to do the spectroscopic observations for their radial velocity curves and the evidence of the third bodies. |
| TNTC011_011 |
Are rapidly rotating M dwarfs flare inactive or are those objects dominated by UV micro-flaring?
Dr. Puji Irawati |
This proposal is a resubmission of TNTC10_001. Observations made using TESS have revealed that the majority of low mass stars which have rotation periods shorter than 0.3d show very few (if any) flares. Given that rapid rotation is the usual sign for high levels of stellar activity this is a surprise. Various explanations have been put forward for this discrepancy but it is currently unresolved. Here we propose to observe a small selection of these low mass stars with a rotation period <0.2 d and show fewer than 1 flare every 27 days (the duration of a TESS sector). Our observations would allow us to determine whether micro-flaring (and/or ultra-violet dominated events) are present which can not be seen by TESS due to their short duration and emission in the ultra-violet. This will allow us to better constrain the interplay between the magnetic energy, stellar rotation, activity level and underlying dynamo action. |
| TNTC011_012 |
Searching for non-accreting compact objects in binaries
Prof. Shengbang Qian |
The demographic and physical properties of compact objects like neutron stars (NSs) and black holes (BHs) hold essential information about the stellar evolution and chemical enrichment history of our Galaxy. Most of the NSs and stellar-mass BHs have been identified by X-rays emitted from gas that is accreting onto the BH or NS from a companion star. Recently, a few non-accreting stellar-mass BHs and NSs have been detected through radial-velocity (RV) measurements of the motion of the companion star, which indicates the optical time-domain surveys can unveil and characterize exciting but less explored non-accreting NSs and stellar-mass BHs in binaries. Based on the LAMOST and TESS data, we have detected a group of variables with large radial velocities, high metallicity, ellipsoidal light curve, or even pulsating ellipsoidal light curve, which are potential candidates of non-accreting NSs and stellar-mass BHs. In this project, we apply to use medium resolution spectrograph of TNT to get the companions 'RV curves of these potential candidates of non-accreting compact objects. Our purpose is searching for non-accreting NSs and stellar-mass BHs in binaries based on their companions 'RV curves and ellipsoidal light curves. |
| TNTC011_013 |
Peculiar Velocity Distribution Analysis of Galactic High-mass X-ray Binaries in Gaia DR3
Ms. Pornisara Nuchvanichakul |
This resubmission is for proposal ID: 20 in cycle 8, ID: 04 in cycle 9. High-mass X-ray binaries (HMXBs) are systems in which a neutron star or black hole accretes material from a massive companion. Companions typically have masses of more than 10 M_⨀. They are divided into three main classes: (i) wind-fed compact objects with supergiant donors (SgXRBs); (ii) compact objects that accrete from a Be star. (BeXRBs); (iii) compact objects accreting via a disc from a Roche-lobe filling companion (RLOs). Most HMXBs are expected to have experienced a supernova in their evolution. The impulsive kick associated with this event should affect the space velocity of the system in a way that depends on the nature and state of the progenitor binary. Interestingly, previous studies with the Hipparcos mission found very high transverse (Vt) sky velocities for the OB supergiant binaries (Chevalier & Ilovaisky 1998) of order Vt ~60 km s-1, much larger than for Be systems. This result suggests a distinct formation channel for these most massive binary systems, which may originate in distinct fractional Helium core masses between the two groups (van den Heuvel et al., 2000). Here, we test whether the different evolutionary histories of HMXBs have left a detectable imprint on their peculiar velocities (Vpec). Using 5-astrometric data from Gaia Data Release 3 (Gaia DR3), we first calculate the peculiar velocities for 60 well-known HMXBs hosting a black hole or neutron star and estimate the associated uncertainties via Monte Carlo re-sampling. We then analyse their distribution and check for differences between classes. The overall range of Vpec values is between ≈2-97 km s-1, but with Be/X-ray binaries (BeXRBs) favouring Vpec < 40 km s-1 and supergiant X-ray binaries (SgXRBs) favouring Vpec > 40 km s-1. Based on a Kolmogorov–Smirnov (K-S) test, the null hypothesis that the peculiar velocities of both classes are drawn from the same parent distribution is rejected at a significance level of 0.05. However, Vr values are not available for all systems, and this is what we would like to measure with the observations proposed. |
| TNTC011_014 |
Transmission spectroscopy and transit timing variations analyses of Jovian planets in the TESS era
Dr. Supachai Awiphan |
As of the present date, more than 5,000 planets have been officially confirmed using a variety of techniques. Among these, over 2,300 planets were identified through the Kepler mission, primarily utilizing the transit method (Morton et al. 2016). Beyond the mere detection of new exoplanets, there is a rapidly advancing field centered on characterizing the atmospheres and properties of these celestial bodies. One technique employed for the study of planetary atmospheres is known as transmission spectroscopy. This method involves measuring changes in transit depth across different wavelengths (Seager & Deming 2010). By utilizing transmission spectroscopy, scientists can infer the absorption spectrum and compositional makeup of a planet's atmosphere. Various transiting exoplanets have been investigated through this approach. Additionally, the transit light curves obtained from these observations can serve to detect other entities within planetary systems through the transit timing variations technique. This proposal is a fundamental component of the global initiative known as SPEARNET (Spectroscopy and Photometry of Exoplanet Atmospheres Research Network). This collaborative effort employs a distributed network of telescopes to analyze exoplanetary atmospheres. Within this proposal, we intend to focus on observing 14 specific targets: WASP-11b, WASP-36b, WASP-143b, WASP-161b, WASP-183b, HAT-P-33b, HAT-P-36b, HAT-P-39b, HAT-P-43b, HAT-P-47b, HAT-P-48b, NGTS-5b, V1298 Tau and K2-237b These targets have been under continuous observation since 2014, utilizing both NARIT facilities and our collaborative telescope network. In the upcoming observational cycle, our plan involves utilizing the TNT for Transmission Spectroscopy and Transit Timing Variations analyses with the ULTRASPEC instrument on the 1.0-meter telescope at TNO, as well as the Thai Robotic Telescopes Network (TRTN). These observations will be focused on conducting transmission spectroscopy and monitoring transit timing variations of the aforementioned exoplanets. This effort is aimed at enhancing our understanding of exoplanetary atmospheres and their surrounding environments. |
| TNTC011_015 |
Atmospheric turbulence profile measurements in the El Niño weather phase
Dr. Timothy Butterley |
The TNT SLODAR instrument has been installed on the telescope since 2019. It has been used to measure statistical turbulence profile data at the site which will be invaluable for future adaptive optics projects on the TNT. All of the data so far has been taken during the La Niña weather phase. The weather pattern has now changed to the El Niño phase, meaning the behaviour of the turbulence profile could be substantially different. We are requesting further SLODAR observing time to investigate the effect of this change. |
| TNTC011_016 |
Radial velocity measurements of ZTF-selected redback pulsar candidates
Dr. Pak-Hin Thomas Tam |
Redbacks are compact binaries being composed of a pulsar and a non-degenerate star with masses of ~0.2 - 1.0 solar mass, and only 14 Galactic field redbacks are known until 2019. Some redbacks (known as “transitional pulsars”, by now only two are known in the field) have been observed to transit between the rotational-powered state and a state with an accretion disk, which are important evolutionary link between X-ray binaries and radio millisecond pulsars (MSPs). Expanding the redback population is an effective way to discover new MSPs (in particular, transitional MSPs and massive neutron stars), which ultimately will help us to understand the recycling of MSPs and to constrain the EoS of neutron stars. Through high-precision ZTF photometric g- and r-band data, we selected the best candidates of redback pulsars. Here, we ask for spectroscopic observations of these best candidates. Such observations will result in radial velocity curves which will serve as a critical step to constrain the system parameters like the orbital geometry as well as the unseen companion masses (in turn, their nature). |
| TNTC011_017 |
Study of variability on spectroscopic data of Wolf-Rayet stars
Mr. Bakuh Danang Setyo Budi |
Massive stars have an important role as metal factories in the Universe. One type of massive star is the Wolf-Rayet star, which has an emission line on its spectrum that exhibits an unusual abundance of helium, nitrogen, carbon, and oxygen elements when compared to the spectrum of other stars in general. A Wolf-Rayet progenitor is a class O star that evolves into a red or yellow supergiant star (RSG or YSG) or a luminous blue variable (LBV), depending on the star's initial mass. Massive stars as well as Wolf-Rayet are known to exhibit photometric and spectroscopic variability, either intrinsic (e.g., pulsational or rotational modulation), or extrinsic (e.g., binary sources or circumstellar dust). In this proposal, we will carry out spectroscopic observations of the Wolf-Rayet stars that exhibit variability in their TESS light curve. We would measure several line parameters, then conduct atmosphere modeling with PoWR for each spectrum. Furthermore, several time series analyses will be conducted to characterize periodicity in Wolf-Rayet spectroscopic data. |
| TRTC011_001 |
Long-term monitoring of the long-period redback pulsar PSR J2129-042 PI: Dr. Siraprapa Sanpa-arsa |
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 a 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 significant clues about the evolution of these systems. Further investigation is warranted as there appears to be a relative flux change in the z band of TNT data from 2017 to 2021. We propose to initiate a bi-annual monitoring campaign in order to 1) track the future behavior of this system and 2) shed light on the physical mechanism responsible for these secular changes. |
| TRTC011_002 |
Transmission spectroscopy and transit timing variations analyses of Jovian planets in the TESS era PI: Dr. Supachai Awiphan |
As of the present date, more than 5,000 planets have been officially confirmed using a variety of techniques. Among these, over 2,300 planets were identified through the Kepler mission, primarily utilizing the transit method (Morton et al. 2016). Beyond the mere detection of new exoplanets, there is a rapidly advancing field centered on characterizing the atmospheres and properties of these celestial bodies. One technique employed for the study of planetary atmospheres is known as transmission spectroscopy. This method involves measuring changes in transit depth across different wavelengths (Seager & Deming 2010). By utilizing transmission spectroscopy, scientists can infer the absorption spectrum and compositional makeup of a planet's atmosphere. Various transiting exoplanets have been investigated through this approach. Additionally, the transit light curves obtained from these observations can serve to detect other entities within planetary systems through the transit timing variations technique. This proposal is a fundamental component of the global initiative known as SPEARNET (Spectroscopy and Photometry of Exoplanet Atmospheres Research Network). This collaborative effort employs a distributed network of telescopes to analyze exoplanetary atmospheres. Within this proposal, we intend to focus on observing 14 specific targets: WASP-11b, WASP-36b, WASP-143b, WASP-161b, WASP-183b, HAT-P-33b, HAT-P-36b, HAT-P-39b, HAT-P-43b, HAT-P-47b, HAT-P-48b, NGTS-5b, V1298 Tau and K2-237b These targets have been under continuous observation since 2014, utilizing both NARIT facilities and our collaborative telescope network. In the upcoming observational cycle, our plan involves utilizing the TNT for Transmission Spectroscopy and Transit Timing Variations analyses with the ULTRASPEC instrument on the 1.0-meter telescope at TNO, as well as the Thai Robotic Telescopes Network (TRTN). These observations will be focused on conducting transmission spectroscopy and monitoring transit timing variations of the aforementioned exoplanets. This effort is aimed at enhancing our understanding of exoplanetary atmospheres and their surrounding environments. |
| TRTC011_003 |
Photometric Variability and Frequency Analysis of High Amplitude Delta Scuti Stars (HADS) PI: Dr. Nareemas Chehlaeh |
This research aims to study photometric variability and Fourier analysis of High Amplitude Delta Scuti stars (HADS), which are interesting short-period variable stars with spectral types between A2V and FOV. They are in the classical cepheid instability strip, which crosses the main-sequence (MS) on the Hertzsprung-Russell (H-R) diagram. Time-series light curve data was accomplished using discrete Fourier transformation. The pulsating properties of the selected HADS stars were analyzed using the Period04 astronomical program. We are going to calculate for new light maximum times, magnitude changes, and pulsation frequencies for each star. Studying the pulsation frequencies, O-C diagram, and period change of HADS stars can estimate their pulsation modes and evolution. Moreover, HADS stars are very important as standard candles that can be used to measure galactic distances. |
