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Home > Recent Colloquia
Title: ALMA Observations of Protostellar Disks and Jets in the Early Stages of Star Formation
Speaker: Chin-Fei Lee 李景輝 (Institute of Astronomy and Astrophysics, Academia Sinica)
Time: 15:30pm 24th Nov. 2017 (Friday)
Venue: R521, IoA, 2nd General Building 綜二館R521

Title: Measuring the magnetic fields in IC5146 cloud

Speaker: Jia-Wei Wang 王嘉瑋 (NTHU)
Time: 15:30pm 10th Nov. 2017 (Friday)
Venue: R521, IoA, 2nd General Building 綜二館R521
Title: The Spiral Structure of the Milky Way Galaxy: A New Picture
Speaker: Prof. Uri (Evgeny) Griv (Ben-Gurion University, Israel)
Time: 15:30pm 3rd Nov. 2017 (Friday)
Venue: R521, IoA, 2nd General Building 綜二館R521
Time: 2PM, October 31, 2017
Venue: R521, IoA, 2nd General Building 綜二館R521
Speaker: Prof. Toshifumi Futamase (Kyoto Sangyo University)
Title: Constraints on neutrino masses from the lensing dispersion of Type Ia supernovae
Title: The circumstellar matter ditribution of MYSOs
Speaker: Dr. Olguin Choupay, Fernando Andres (NTHU)
Time: 15:30pm 27th Oct. 2017 (Friday)
Vanue: R521, IoA, 2nd General Building 綜二館R521
Title: Observing the Orion-KL region with ALMA
Speaker: Dr. Laurent Pagani (The National Center for Scientific Research & Observatoire de Paris, France)
Time: 15:30pm 20th Oct. 2017 (Friday)
Vanue: R521, IoA, 2nd General Building 綜二館R521
Title: Physics of the first Stars, Supernovae, and Galaxies
Speaker: Dr. Chen, Ken 陳科榮 (Institute of Astronomy and Astrophysics, Academia Sinica)
Time: 15:30pm 13th Oct. 2017 (Friday)
Vanue: R521, IoA, 2nd General Building 綜二館R521
Title: Our Place in the Universe
Speaker: Prof. Sun Kwok 郭新 (The University of Hong Kong)
Time: 15:30pm 6th Oct. 2017 (Friday)
Vanue: R521, IoA, 2nd General Building 綜二館R521


Title: The Challenges and Joy of Doing Astronomy
Speaker: Professor Kong, Albert 江國興 (NTHU)
Time: 15:30pm 29nd Sep. 2017 (Friday)
Vanue: R521, IoA, 2nd General Building 綜二館R521

Title: Cosmological simulation with Dust Formation and Destruction with ISM physics

Speaker: Dr. Aoyama, Shohei 青山尚平 (Academia Sinica Institute of Astronomy and Astrophysics)

Time: 3:30pm 22nd Sep. 2017 (Friday)

Vanue: R521, IoA, 2nd General Building 綜二館R521


Time: 2pm, Monday, August 14
Venue: R521, IoA, 2nd General Building
Speaker: Prof. Alex Lazarian (University of Wisconsin-Madison) 
Title: New way to study interstellar magnetic fields: velocity gradients



Special Seminar

Title:  Large Millimeter Bolometric Arrays for Cosmic Microwave Background Observations


Shuay-Pwu Patty Ho (Princeton University)


2pm-3pm, Thursday, August 3 at General Building II R521, IoA


The cosmic microwave background (CMB) continues to reveal new aspects of the large scale universe. For example, current projects are searching for evidence of primordial gravitational waves, for signatures sensitive to the sum of the neutrino masses, and for further understanding of the formation and growth of large structures under the influence of gravity in the accelerating universe. Technologies for ground-based and balloon-borne instruments measuring the polarization of the CMB have been well established and advanced in the last decade.

Two upgraded bolometric polarimeters on the Atacama Cosmology Telescope (ACT), the ACT Polarimeter (ACTPol) and the Advanced ACTPol, have made and will make sensitive measurements of the temperature and polarization in the Cosmic Microwave Background (CMB) with arcminute resolution.  In this talk, I will focus on the instrumentation of these state-of-the-art arrays, especially the Advanced ACTPol ones. I will conclude with the results coming from the two-season cosmological results presented in Louis et al. (2016) and describe the current progress on the all three ACTPol seasons.


Special Seminar

Title:  Evolutionary Description of Giant Molecular Cloud Mass Functions on Galactic Disks

Masato Kobayashi (Nagoya University, Japan)

2pm-3pm, Monday, July 10 at GEN II R521


Recent radio observations show that giant molecular cloud (GMC) mass functions noticeably vary across galactic disks (e.g., Colombo et al. 2014). High-resolution magnetohydrodynamics simulations show that multiple episodes of compression are required for creating a molecular cloud in the magnetized interstellar medium (e.g., Inoue et al. 2012). To understand time evolution of GMC mass functions, we formulate the evolution equation for the GMC mass function to reproduce the observed profiles, for which multiple compressions are driven by a network of expanding shells due to H II regions and supernova remnants. We also introduce the cloud-cloud collision (CCC) terms in the evolution equation in contrast to previous work. In this seminar, I would like to present computed time evolutions and the following two suggestions:

(1) the GMC mass function slope is governed by the ratio of GMC formation timescale to its dispersal timescale whereas the CCC effect is limited only in the massive end of the profile,

(2) almost all of the dispersed gas contributes to the mass growth of pre-existing GMCs in arm regions whereas less than 60 percent contributes in inter-arm regions. Our results suggest that measurement of the GMC mass function slope provides a powerful method to constrain those GMC timescales and the gas resurrecting factor in various environments across galactic disks.

Time Coordinate: 3:30 pm 9th June 2017 (Friday)

Space Coordinate: NTHU General Building II, R521

Speaker: He-Feng Hsieh and Ing-Guey Jiang (NTHU)

Title: Imaging the Exoplanets


Imaging method is a viable pathway to detect exoplanet and characterize the planetary atmosphere. However, imaging exoplanets is challenging due to the small angular separation and extreme intensity contrast between the exoplanet and its host star (~1e-4 for self-luminous giant planets and ~1e-10 for rocky planets). Collaborating with Nanjing Institute of Astronomical Optics & Technology, Chinese Academy of Sciences, we are developing next generation Adaptive Optic (AO) systems aiming to detect and characterize rocky exoplanets. The design of AO systems, the observation strategy, data reduction techniques, and the method for retrieving physical properties of imaged objects will be introduced in this talk.


Time Coordinate: 3:30 pm 2nd June 2017 (Friday)

Space Coordinate: NTHU General Building II, R521


Speaker A: Chia-Hsuan Cheng (NTHU)

Title: Variations of the x-ray flux from the globular cluster black hole


Speaker B: Ren-Yi Deng (NTHU)

Title: Predicting the spectrum of ejection velocities of hypervelocity stars

Time Coordinate: 3:30 pm 26th May 2017 (Friday)

Space Coordinate: NTHU General Building II, R521


Speaker A: Hao-Yuan Duan (NTHU)

Title: Kinematics of a Young Low-mass Star-forming Core


Speaker B: Sheng-Jun Lin (NTHU)

Title: Detection of Interstellar Ortho-D2H+ with SOFIA

Title: Statistical analysis of the observational data of Gamma Ray Bursts (GRBs)

Speaker: Dr. Jakub Ripa  (Leung Center for Cosmology and Particle Astrophysics National Taiwan University)

Time: 12:20pm, May 25 (Thu), 2017

Location: Room 501, The 2nd General Building

Time Coordinate: 3:30 pm 12th May 2017 (Friday)

Space Coordinate: NTHU General Building II, R521


Speaker A: Pou-Ieng Cheong (NTHU)

Title: ALMA Observations of Spiral Accretion Flows Towards Extremely Young Protostars


Studying the accretion flows toward extremely young protostars is an important step for understanding how the protostars and the protoplanetary disks are assembled in the early stage of star formation. The accretion flows are commonly seen in the MHD numerical simulations; however, it is rarely observed toward young protostars. Here we present our ALMA observations of the accretion flows around the extremely young protostar VLA1623A with a Keplerian disk likely just formed (Murillo, Lai, et al. 2013). "Dendrogram" algorithm (Goodman et al. 2009) are used to identify the accretion flows, and we find the three brightest "branches" and their associated "leaves" likely correspond to the spiral structure flowing toward the central young cluster. We further compare the three accretion flows in the position-position-velocity cube to the CMU model (Ulrich 1976; Cassen & Moosman 1981) which describe the velocity structure of the gas accreting to the central protostar with constant angular momentum. We find that our identified branch structures well match with the CMU model.


Speaker B: Li-Wen Liao (NTHU)

Title: Anatomy of the internal bow shocks in protostellar jet

Time Coordinate: 3:30 pm 5th May 2017 (Friday)

Space Coordinate: NTHU General Building II, R521

Speaker: Dr. Lung-Yih Chiang (ASIAA)

Title: Excessive shift of the CMB acoustic peaks of the Cold Spot area


Measurement of the acoustic peak positions of the cosmic microwave background (CMB) temperature anisotropies has been instrumental in deciding the geometry and content of the universe. Acoustic peak positions vary from patch to patch in different parts of the sky due to statistical fluctuation. We present the statistics of the peak positions of small patches from ESA Planck data. It is found that the peak positions have significantly high variance compared to the 100 CMB simulations with best-fit LambdaCDM model with lensing and Doppler boosting effects included, both of which can significantly shift the peaks of small patches. 

Examining individual patches, we find the one containing the mysterious "Cold Spot", an area near the Eridanus constellation where the temperature is lower than Gaussian theory predicts, displays large synchronous shift of peak positions towards smaller multipole numbers (i.e. larger scales) with significance lower than 1.11 x 10^{-4}. The combination of large synchronous shifts in acoustic peaks and lower than usual temperature at the Cold Spot area results in a 4.73 sigma detection (significance p~1.11 x 10^{-6}) against the LambdaCDM model, prompting us to propose one of the possible accounts for both anomalies: some localised unknown force to stretch the space around the Cold Spot area so that the acoustic peak positions are shifted towards large scales and the temperature is dragged down.