Xihe Liu (刘羲和)

About me

Hi there! My name is Xihe Liu(刘羲和). I am an undergraduate student in the Physics Department at Shandong University, class of 2025. I am working in ATOMS(ALMA Three-millimeter Observations of Massive Star-forming regions) group. (PI: Dr.Tie Liu) Currently, I'm working in ATOMS group with Prof. Guido Garay at Department of Astronomy, University of Chile.

I'm interested in studying ISM and Star formation using continuum and molecular lines, mainly analyze the data from the (sub)millimeter observations with interferometers (e.g., SMA and ALMA). Besides, I am also interested in using numerical simulation to study the star formation.

During my spare time, I enjoy indulging in life's pleasures, such as playing saxophone, reading, watching movies, and traveling.

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Research

Keywords: Star formation, ISM, CMZ, Continuum, Molecular lines, Magnetic field, Numerical simulation

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Analysis of the CMZ Cloud 'e' using ALMA Band 3&6

The Central Molecular Zone (CMZ) , being close to Sgr A* at Milky Way center, is characterized by high temperatures, elevated densities, and strong magnetic fields, rendering it an ideal laboratory for studying star formation in extreme environments. Besides, the SFR within the CMZ is ten times lower than expected from the dense gas star formation relation extrapolated from the nearby molecular clouds(Longmore et al. 2013a; Kruijssen et al. 2014; Barnes et al. 2017). This unanticipated attribute, coupled with the dearth of associated research investigations, has rendered the exploration of the CMZ region a prominent subject in recent years.

In preceding studies, a distinct area referred to as "Cloud 'e'" in CMZ was identified as harboring numerous dense cores. Consequently, this investigation employed higher resolution observations (0.3''*0.2'') obtained from ALMA bands 3 & 6 to identify these cores. As shown in the figure on the left, we identify 33 dense cores simultaneously in both two bands (indicated by purple contours) using 5 rms. Additionally, 9 cores are only detected in band3 (indicated by red contours), and 75 cores are exclusively detected in band6 (indicated by cyan contours).

In addition, as shown in the right figure, we also obtain the flux at each pixel and core of this region and calculate the spectral index. We find that most of the spectral indices are greater than 2, indicating a good fit to optically thin dust emission. We also analyze the fragmentation of filaments, spatial distribution of cores, and mass segregation in Cloud 'e'.

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Outreach

I chase the boundless stars, also try to protect the shimmering starlight in others' eyes.

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Astrophysics Party

Emulating Astrobites, I established Chinese first academic exchange community specifically for undergraduats majoring in astrophysics. We discuss the latest papers on arXiv every week, supporting each other and solving academic problems together. Every Saturday night, I invite Chinese astronomers from different institutions to present their work to help undergraduates gain understanding of research in different topic. Through our efforts, scattered Chinese astrophysics undergraduates have transformed into a tightly-knit community. Today, there are over 400 members including undergraduats as well as PhD candidates and faculty members participating in this community.

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Astronomy Science Popularization

During my undergrad, I participated in numerous astronomy outreach, writing my teaching plans and delivering astronomy popularization courses at elementary schools. These efforts were well-received by children.

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Astronomy by The Road

On clear nights, there is always a group of people on the campus of Shandong University who set up telescopes in some areas away from light pollution and continuously invite passing students to admire the beautiful night sky, and I am also one of the organizers of this activity. On those wonderful evenings, we gaze at the stars together, chat happily, and hope that the night will last a little longer.

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Activities

2024.03 - Present : Undergraduate Research Program

Dapartment of Astronomy, Universidad de Chile
Advisor : Prof. Guido Garay and Dr. Tie Liu

Currently, we selected four sources in ATOMS project data(I13484-6100, I16272-4837, I18182-1433, I18264-1152) and using molecular lines(SiO(1-0), HCN(1-0), CCH(1-0), etc..) to analyse the hub-filament structure in these sources.

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2024.06 : 244th Meeting of the American Astronomical Society

Madsion, WI, USA

Poster (ALMA-ATOMS IRAS13484 source: Gas Inflow along HFSs and Outflows)

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2023.11 - 2024.01 : Undergraduate Research Program

Shanghai Astronomical Observatory, Chinese Academy of Sciences
Advisor : Prof. PakShing Li and Dr. Tie Liu

During this period, I learned the use of numerical simulations in investigating ISM and Star formation. We focus on studying a filament-shaped structure, analyzing its magnetic field, and optimizing the DCF function in our research.

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2023.10 : 2023 Annual Symposium on Molecular Clouds and Star Formation

Chongqing, China

Poster (DUET: The Band3 and Band6 Continuum Emission and Dense Cores in the Dust Ridge Cloud ‘e’)

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2023.09 : 2023 Peking University Undergraduate Astronomy Symposium (Linbridge Scholarship)

Beijing, China

Oral Presentation (Analysis of Dense Cores and Filamentary Structures within CMZ cloud ‘e’ using ALMA Band 3 & 6)

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2023.09 : 2023 Annual Meeting of the Chinese Astronomical Society

Weihai, China

Participate without Report

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2022.09 - 2024.09 : Undergraduate Research Program

Shanghai Astronomical Observatory, Chinese Academy of Sciences
Advisor : Dr. Xing Lu and Dr. Tie Liu

I processed the continuum spectral index of ALMA's band 3 & band 6 in the Cloud 'e' region of the Central Molecular Zone (CMZ) in our Milky Way. By calculating spectral indices, we identified optically thin dust emission in this region. Additionally, we also identified dense cores and analyzed filament fragmentation.

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CV

ALMA Array from above. © Liam Young

If you want to view my CV, please Check here.

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