內容. 蝘蜓—蒼蠅座分子雲的低質量恆星形成區距離太陽約 200 秒差距。前人
文獻已經多次普查這些年輕恆星族群，但研究的範圍幾乎只聚焦在分子雲本
身。
目標. 為了診斷蝘蜓—蒼蠅座分子雲的恆星形成歷史，我們除了尋找在分子雲
上的年輕成員星之外，也調查雲以外的區域。
方法. 我們研究比前人文獻廣上許多的區域12◦ × 12◦，利用 Gaia DR3 提供
的高度精確測光以及天體測量數據，加上近紅外波段 2MASS 與中紅外波段
ALLWISE 的顏色，尋找年輕恆星成員。
結果. 我們確認蝘蜓 I 的恆星形成是這個區域中最活躍的，有近 200 顆的年輕
恆星成員。蝘蜓 II 擁有 50 幾顆年輕恆星，而其中三顆位在蝘蜓 III 的北邊，但
蝘蜓 III 本身沒有自己的恆星形成。蒼蠅座分子雲也沒有年輕恆星，但根據文獻
它孕育了原恆星核，表示正處於誕生恆星的前期狀態。Cha I 的成員可以從距
離分為南邊 189−5
+5 秒差距與北邊 193−3
+2 秒差距，而 Cha II 的成員星大約落在
197−5
+5 秒差距，這兩個年輕恆星族群的年齡大約是三百萬年。位在我們研究的
恆星形成區的前景(約 110 秒差距)，我們找到一些 ε Cha 和下半人馬-南十字座
的星協成員，他們是演化更久的年輕恆星或是主序星，年齡分佈廣從五百萬至
兩千萬年。
總結. 在分子雲裡的已知成員星，與我們新找到的雲外的成員星，有一致的距
離與年齡，推測這可能是附近的 OB 星協影響蝘蜓—蒼蠅座分子雲的恆星誕
生。

Context. The Chamaeleon-Musca dark cloud complex is a known low-mass
star-forming region at a distance of ∼200 pc. The young stellar populations
have been investigated in previous works, but mostly focused toward the main
clouds.
Aims. We searched for young members not only associated with the main
clouds but also in intercloud regions in order to diagnose the star formation
history of the entire complex.
Method. By using Gaia DR3 data, which provide unprecedentedly precise
photometry and astrometry for membership, and near- and mid-infrared photometry from 2MASS and ALLWISE for stellar youth, we investigate a sky area
of 12◦ × 12◦
toward the cloud complex, much larger than previously reported in
the literature.
Results. We confirm that Cha I is active in star formation, with nearly 200
young members. There are more than 50 young members in Cha II, among
which three are projected in northern Cha III which itself lacks any star-forming
activity. The Musca cloud harbors no young star, though it is known to host
prestellar cores. Cha I indeed as known has two subclusters, with the northern
group at 193+2
−3 pc and the southern group at 189+5
−5 pc. Cha II is at 197+5
−5 pc,
and has an age of about 3 Myr as in Cha I. Some members of ϵ Cha and Lower
Centaurus-Crux associations projected in the foreground (∼110 pc) toward our
studied region are found to be evolved young stars or dwarfs, with a wide age
spread of ∼5–20 Myr.
Conclusions. Our reliable sample of young stellar members provides accurate diagnosis of distance, age, and their relation to parental molecular clouds,
including those already known in the literature, plus a few newly found offcloud members, suggesting a coeval star formation likely influenced by nearby
OB stars.
Thesis Supervisor: Wen-Ping Chen
Title: Professor

Alcalá, J. M. et al. (Mar. 2000). “A ROSAT pointed observation of the
Chamaeleon II dark cloud”. In: Astronomy and Astrophysics 355, pp. 629–638.
Alcalá, Juan M. et al. (Mar. 2008). “The Spitzer c2d Survey of Large, Nearby,
Interstellar Clouds. X. The Chamaeleon II Pre-Main-Sequence Population as
Observed with IRAC and MIPS”. In: Astrophysical Journal 676.1, pp. 427–463.
DOI: 10.1086/527315. arXiv: 0802.1424 [astro-ph].
Bertout, C., N. Robichon, and F. Arenou (Dec. 1999). “Revisiting Hipparcos data
for pre-main sequence stars”. In: Astronomy and Astrophysics 352, pp. 574–
586. DOI: 10.48550/arXiv.astro- ph/9909438. arXiv: astro- ph/
9909438 [astro-ph].
Bessell, M. S. and J. M. Brett (Sept. 1988). “JHKLM Photometry: Standard Systems,
Passbands, and Intrinsic Colors”. In: Publications of the ASP 100, p. 1134.
DOI: 10.1086/132281.
Bonne, L. et al. (Dec. 2020). “Formation of the Musca filament: evidence for
asymmetries in the accretion flow due to a cloud-cloud collision”. In: Astronomy
and Astrophysics 644, A27, A27. DOI: 10 . 1051 / 0004 - 6361 /
202038281. arXiv: 2010.12479 [astro-ph.GA].
Bressan, Alessandro et al. (Nov. 2012). “PARSEC: stellar tracks and isochrones
with the PAdova and TRieste Stellar Evolution Code”. In: Monthly Notices of
the RAS 427.1, pp. 127–145. DOI: 10.1111/j.1365-2966.2012.21948.x.
arXiv: 1208.4498 [astro-ph.SR].
Cambrésy, L. (May 1999). “Mapping of the extinction in giant molecular clouds
using optical star counts”. In: Astronomy and Astrophysics 345, pp. 965–976.
DOI: 10 . 48550 / arXiv . astro - ph / 9903149. arXiv: astro - ph /
9903149 [astro-ph].
Cambresy, L. et al. (Aug. 1997). “Extinction map of Chamaeleon I molecular
cloud with DENIS star counts.” In: Astronomy and Astrophysics 324, pp. L5–
L8. DOI: 10.48550/arXiv.astro- ph/9706035. arXiv: astro- ph/
9706035 [astro-ph].
Chen, H. et al. (Mar. 1997). “Comparison of Star Formation in Five Nearby
Molecular Clouds”. In: Astrophysical Journal 478.1, pp. 295–312. DOI: 10 .
1086/303769.
Cohen, J. G. et al. (Oct. 1981). “Bolometric luminosities and infrared properties
of carbon stars in the Magellanic Clouds and the galaxy.” In: Astrophysical
Journal 249, pp. 481–503. DOI: 10.1086/159308.

Comerón, F., G. H. Rieke, and R. Neuhäuser (Mar. 1999). “Faint members of the
Chamaeleon I cloud”. In: Astronomy and Astrophysics 343, pp. 477–495.
Cutri, R. M. et al. (Nov. 2013). Explanatory Supplement to the AllWISE Data Release
Products. Explanatory Supplement to the AllWISE Data Release Products, by
R. M. Cutri et al.
Dobashi, Kazuhito et al. (Feb. 2005). “Atlas and Catalog of Dark Clouds Based
on Digitized Sky Survey I”. In: Publications of the ASJ 57, S1–S386. DOI: 10.
1093/pasj/57.sp1.S1.
Dougherty, S. M. et al. (Oct. 1994). “Near-IR excess of Be stars.” In: Astronomy
and Astrophysics 290, pp. 609–622.
Esplin, T. L. et al. (Aug. 2017). “A Survey for Planetary-mass Brown Dwarfs
in the Chamaeleon I Star-forming Region”. In: Astronomical Journal 154.2,
46, p. 46. DOI: 10 . 3847 / 1538 - 3881 / aa74e2. arXiv: 1706 . 00058
[astro-ph.SR].
Feigelson, Eric D. and Warrick A. Lawson (Oct. 2004). “An X-Ray Census of
Young Stars in the Chamaeleon I North Cloud”. In: Astrophysical Journal
614.1, pp. 267–283. DOI: 10.1086/423613. arXiv: astro- ph/0406529
[astro-ph].
Feigelson, Eric D. et al. (Oct. 1993). “ROSAT X-Ray Study of the Chamaeleon I
Dark Cloud. I. The Stellar Population”. In: Astrophysical Journal 416, p. 623.
DOI: 10.1086/173264.
Fernández, D., F. Figueras, and J. Torra (Mar. 2008). “On the kinematic evolution
of young local associations and the Scorpius-Centaurus complex”. In:
Astronomy and Astrophysics 480.3, pp. 735–751. DOI: 10.1051/0004-6361:
20077720. arXiv: 0801.0605 [astro-ph].
Franco, G. A. P. (Nov. 1991). “The interstellar extinction towards selected area
203 : a distance estimation to the Chamaeleon-Musca dark clouds complex.”
In: Astronomy and Astrophysics 251, p. 581.
Gaia Collaboration et al. (Nov. 2016). “Gaia Data Release 1. Summary of the
astrometric, photometric, and survey properties”. In: Astronomy and Astrophysics
595, A2, A2. DOI: 10.1051/0004-6361/201629512. arXiv: 1609.
04172 [astro-ph.IM].
Gaia Collaboration et al. (June 2023). “Gaia Data Release 3. Summary of the
content and survey properties”. In: Astronomy and Astrophysics 674, A1,
A1. DOI: 10 . 1051 / 0004 - 6361 / 202243940. arXiv: 2208 . 00211
[astro-ph.GA].
Galli, P. A. B. et al. (Feb. 2021). “Chamaeleon DANCe. Revisiting the stellar
populations of Chamaeleon I and Chamaeleon II with Gaia-DR2 data”. In:
Astronomy and Astrophysics 646, A46, A46. DOI: 10 . 1051 / 0004 - 6361 /
202039395. arXiv: 2012.00329 [astro-ph.GA].

Gavras, Panagiotis et al. (June 2023). “Gaia Data Release 3. Cross-match of Gaia
sources with variable objects from the literature”. In: Astronomy and Astrophysics
674, A22, A22. DOI: 10 . 1051 / 0004 - 6361 / 202244367. arXiv:
2207.01946 [astro-ph.IM].
Gavrilchenko, Tatyana et al. (June 2014). “A mid-infrared study of RR Lyrae
stars with the Wide-field Infrared Survey Explorer all-sky data release”. In:
Monthly Notices of the RAS 441.1, pp. 715–725. DOI: 10 . 1093 / mnras /
stu606. arXiv: 1312.4643 [astro-ph.SR].
Goldman, Bertrand et al. (Nov. 2018). “A Large Moving Group within the Lower
Centaurus Crux Association”. In: Astrophysical Journal 868.1, 32, p. 32. DOI:
10.3847/1538-4357/aae64c. arXiv: 1807.02076 [astro-ph.SR].
Gregorio Hetem, J. C., G. C. Sanzovo, and J. R. D. Lepine (Dec. 1988). “Star
counts and IRAS sources in the southern dark clouds.” In: Astronomy and
Astrophysics, Supplement 76, pp. 347–363.
Hartigan, Patrick (Apr. 1993). “New T Tauri Stars in Chamaeleon I and
Chamaeleon II”. In: Astronomical Journal 105, p. 1511. DOI: 10 . 1086 /
116530.
Hayakawa, Takahiro et al. (Dec. 2001). “CO Column Density and Extinction in
the Chamaeleon II–III Dark-Cloud Complex”. In: Publications of the ASJ 53.6,
pp. 1109–1118. DOI: 10.1093/pasj/53.6.1109.
He, Zhihong et al. (Sept. 2022). “A Blind All-sky Search for Star Clusters in
Gaia EDR3: 886 Clusters within 1.2 kpc of the Sun”. In: Astrophysical Journal,
Supplement 262.1, 7, p. 7. DOI: 10.3847/1538-4365/ac7c17. arXiv:
2206.12170 [astro-ph.GA].
Henize, Karl G. (Jan. 1963). “Emission-Line Stars in an Obscured Region in
Chamaeleon.” In: Astronomical Journal 68, p. 280. DOI: 10.1086/109141.
Hernández, Jesús et al. (Feb. 2005). “Herbig Ae/Be Stars in nearby OB Associations”.
In: Astronomical Journal 129.2, pp. 856–871. DOI: 10.1086/426918.
arXiv: astro-ph/0410494 [astro-ph].
Hunt, Emily L. and Sabine Reffert (May 2023). “Improving the open cluster census.
II. An all-sky cluster catalogue with Gaia DR3”. In: Astronomy and Astrophysics
673, A114, A114. DOI: 10.1051/0004-6361/202346285. arXiv:
2303.13424 [astro-ph.GA].
Jayasinghe, T. et al. (Oct. 2020). VizieR Online Data Catalog: ASAS-SN catalog of
variable stars (Jayasinghe+, 2018-2020). VizieR On-line Data Catalog: II/366.
Originally published in: 2018MNRAS.477.3145J.
Knude, J. and E. Hog (Oct. 1998). “Interstellar reddening from the HIPPARCOS
and TYCHO catalogues. I. Distances to nearby molecular clouds and star
forming regions”. In: Astronomy and Astrophysics 338, pp. 897–904.

Koenig, X. P. and D. T. Leisawitz (Aug. 2014). “A Classification Scheme for
Young Stellar Objects Using the Wide-field Infrared Survey Explorer All-
WISE Catalog: Revealing Low-density Star Formation in the Outer Galaxy”.
In: Astrophysical Journal 791.2, 131, p. 131. DOI: 10.1088/0004-637X/791/
2/131. arXiv: 1407.2262 [astro-ph.GA].
Kubiak, K. et al. (June 2021). “New low-mass members of Chamaeleon I and
Cha”. In: Astronomy and Astrophysics 650, A48, A48. DOI: 10.1051/0004-
6361/202039899. arXiv: 2102.05589 [astro-ph.SR].
Lada, Charles J. (Jan. 1987). “Star formation: from OB associations to protostars.”
In: Star Forming Regions. Ed. by Manuel Peimbert and Jun Jugaku. Vol. 115,
p. 1.
Lightkurve Collaboration et al. (Dec. 2018). Lightkurve: Kepler and TESS time series
analysis in Python. Astrophysics Source Code Library, record ascl:1812.013.
Lopez Martí, B. et al. (Mar. 2013). “Proper motions of young stars in
Chamaeleon. I. A Virtual Observatory study of spectroscopically confirmed
members”. In: Astronomy and Astrophysics 551, A46, A46. DOI: 10.1051/
0004-6361/201220128. arXiv: 1302.7167 [astro-ph.SR].
Luhman, K. L. (Jan. 2022). “A Census of the Stellar Populations in the Sco-Cen
Complex”. In: Astronomical Journal 163.1, 24, p. 24. DOI: 10.3847/1538-
3881/ac35e2. arXiv: 2111.13946 [astro-ph.GA].
— (2008). “Chamaeleon”. In: Handbook of Star Forming Regions, Volume II. Ed. by
B. Reipurth. Vol. 5, p. 169. DOI: 10.48550/arXiv.0808.3207.
— (Nov. 2007). “The Stellar Population of the Chamaeleon I Star-forming Region”.
In: Astrophysical Journal, Supplement 173.1, pp. 104–136. DOI: 10 .
1086/520114. arXiv: 0710.3037 [astro-ph].
Machaieie, Dinelsa A. et al. (Feb. 2017). “Properties of Dense Cores Embedded
in Musca Derived from Extinction Maps and 13CO, C18O, and NH3 Emission
Lines”. In: Astrophysical Journal 836.1, 19, p. 19. DOI: 10.3847/1538-4357/
836/1/19.
Maíz Apellániz, J. et al. (Sept. 2023). “Stellar variability in Gaia DR3. I. Threeband
photometric dispersions for 145 million sources”. In: Astronomy and Astrophysics
677, A137, A137. DOI: 10.1051/0004-6361/202346759. arXiv:
2304.14249 [astro-ph.SR].
Marton, G. et al. (June 2016). “An all-sky support vector machine selection of
WISE YSO candidates”. In: Monthly Notices of the RAS 458.4, pp. 3479–3488.
DOI: 10.1093/mnras/stw398. arXiv: 1602.05777 [astro-ph.IM].
Meyer, Michael R., Nuria Calvet, and Lynne A. Hillenbrand (July 1997). “Intrinsic
Near-Infrared Excesses of T Tauri Stars: Understanding the Classical T
Tauri Star Locus”. In: Astronomical Journal 114, pp. 288–300. DOI: 10.1086/
118474.

Mizuno, Akira et al. (Dec. 2001). “A Large Scale 12CO (J = 1 – 0) Survey toward
the Chamaeleon Region with NANTEN”. In: Publications of the ASJ 53.6,
pp. 1071–1080. DOI: 10.1093/pasj/53.6.1071.
Mizuno, Akira et al. (Dec. 1999). “Dense Cores and Star-Formation Activities in
the Chamaeleon Dark-Cloud Complex”. In: Publications of the ASJ 51, pp. 859–
870. DOI: 10.1093/pasj/51.6.859.
Mowlavi, N. et al. (Apr. 2021). “Large-amplitude variables in Gaia Data Release
2. Multi-band variability characterization”. In: Astronomy and Astrophysics
648, A44, A44. DOI: 10 . 1051 / 0004 - 6361 / 202039450. arXiv: 2009 .
07746 [astro-ph.SR].
Murphy, Simon J., Warrick A. Lawson, and Michael S. Bessell (Oct. 2013). “Reexamining
the membership and origin of the Cha association”. In: Monthly
Notices of the RAS 435.2, pp. 1325–1349. DOI: 10.1093/mnras/stt1375.
arXiv: 1305.4177 [astro-ph.SR].
Nardiello, D. (Nov. 2020). “A PSF-based Approach to TESS High quality data
Of Stellar clusters (PATHOS) - III. Exploring the properties of young associations
through their variables, dippers, and candidate exoplanets”. In:
Monthly Notices of the RAS 498.4, pp. 5972–5989. DOI: 10.1093/mnras/
staa2745. arXiv: 2009.02330 [astro-ph.SR].
Nardiello, D. et al. (Dec. 2019). “A PSF-based Approach to TESS High quality
data Of Stellar clusters (PATHOS) - I. Search for exoplanets and variable stars
in the field of 47 Tuc”. In: Monthly Notices of the RAS 490.3, pp. 3806–3823. DOI:
10.1093/mnras/stz2878. arXiv: 1910.03592 [astro-ph.SR].
Nguyen, C. T. et al. (Sept. 2022). “PARSEC V2.0: Stellar tracks and isochrones
of low- and intermediate-mass stars with rotation”. In: Astronomy and Astrophysics
665, A126, A126. DOI: 10.1051/0004-6361/202244166. arXiv:
2207.08642 [astro-ph.SR].
Prisinzano, L. et al. (Aug. 2022). “Low-mass young stars in the Milky Way unveiled
by DBSCAN and Gaia EDR3: Mapping the star forming regions within
1.5 kpc”. In: Astronomy and Astrophysics 664, A175, A175. DOI: 10.1051/
0004-6361/202243580. arXiv: 2206.00249 [astro-ph.GA].
Ratzenböck, Sebastian et al. (Oct. 2023). “The star formation history of the Sco-
Cen association. Coherent star formation patterns in space and time”. In:
Astronomy and Astrophysics 678, A71, A71. DOI: 10 . 1051 / 0004 - 6361 /
202346901. arXiv: 2302.07853 [astro-ph.SR].
Riello, M. et al. (May 2021). “Gaia Early Data Release 3. Photometric content
and validation”. In: Astronomy and Astrophysics 649, A3, A3. DOI: 10.1051/
0004-6361/202039587. arXiv: 2012.01916 [astro-ph.IM].
Robrade, J. and J. H. M. M. Schmitt (Jan. 2007). “A deep XMM-Newton X-ray
observation of the Chamaeleon I dark cloud”. In: Astronomy and Astrophysics

461.2, pp. 669–678. DOI: 10.1051/0004-6361:20066250. arXiv: astroph/
0610778 [astro-ph].
Roccatagliata, V. et al. (Sept. 2018). “The double population of Chamaeleon I
detected by Gaia DR2”. In: Astronomy and Astrophysics 617, L4, p. L4. DOI: 10.
1051/0004-6361/201833890. arXiv: 1808.06931 [astro-ph.SR].
Schwartz, R. D. (Oct. 1977). “A survey of southern dark clouds for Herbig-Haro
objects and H-alpha emission stars.” In: Astrophysical Journal, Supplement 35,
pp. 161–170. DOI: 10.1086/190473.
Shu, Frank H., Fred C. Adams, and Susana Lizano (Jan. 1987). “Star formation
in molecular clouds: observation and theory.” In: Annual Review of Astronomy
and Astrophysics 25, pp. 23–81. DOI: 10.1146/annurev.aa.25.090187.
000323.
Skrutskie, M. F. et al. (Feb. 2006). “The Two Micron All Sky Survey (2MASS)”.
In: Astronomical Journal 131.2, pp. 1163–1183. DOI: 10.1086/498708.
Spezzi, Loredana et al. (June 2008). “The Young Population of the Chamaeleon II
Dark Cloud”. In: Astrophysical Journal 680.2, pp. 1295–1318. DOI: 10.1086/
587931. arXiv: 0802.4351 [astro-ph].
te Lintel Hekkert, P. et al. (Oct. 1991). “1612 MHz OH survey of IRAS point
sources. I. Observations made at Dwingloo, Effelsberg and Parkes.” In: Astronomy
and Astrophysics, Supplement 90, p. 327.
Tritsis, A. et al. (Aug. 2022). “The musca molecular cloud: The perfect ’filament’
is still a sheet”. In: Monthly Notices of the RAS 514.3, pp. 3593–3603. DOI: 10.
1093/mnras/stac1572. arXiv: 2206.04074 [astro-ph.GA].
Villenave, M. et al. (Sept. 2021). “Probing protoplanetary disk evolution
in the Chamaeleon II region”. In: Astronomy and Astrophysics 653, A46,
A46. DOI: 10 . 1051 / 0004 - 6361 / 202140496. arXiv: 2106 . 13847
[astro-ph.SR].
Voirin, Jordan, Carlo F. Manara, and Timo Prusti (Mar. 2018). “A revised estimate
of the distance to the clouds in the Chamaeleon complex using the
Tycho-Gaia Astrometric Solution”. In: Astronomy and Astrophysics 610, A64,
A64. DOI: 10 . 1051 / 0004 - 6361 / 201731153. arXiv: 1710 . 04528
[astro-ph.SR].
Wang, Shu and Xiaodian Chen (June 2019). “The Optical to Mid-infrared Extinction
Law Based on the APOGEE, Gaia DR2, Pan-STARRS1, SDSS, APASS,
2MASS, and WISE Surveys”. In: Astrophysical Journal 877.2, 116, p. 116. DOI:
10.3847/1538-4357/ab1c61. arXiv: 1904.04575 [astro-ph.GA].
Whittet, D. C. B. et al. (Jan. 1987). “A study of the Chamaeleon dark cloud and
T-association -I.Extinction, distance and membership.” In: Monthly Notices of
the RAS 224, pp. 497–512. DOI: 10.1093/mnras/224.2.497.
Whittet, D. C. B. et al. (Nov. 1997). “On the distance to the Chamaeleon I and II
associations”. In: Astronomy and Astrophysics 327, pp. 1194–1205.

Wright, Edward L. et al. (Dec. 2010). “The Wide-field Infrared Survey Explorer
(WISE): Mission Description and Initial On-orbit Performance”. In: Astronomical
Journal 140.6, pp. 1868–1881. DOI: 10.1088/0004-6256/140/6/1868.
arXiv: 1008.0031 [astro-ph.IM].
Zari, E. et al. (Dec. 2018). “3D mapping of young stars in the solar neighbourhood
with Gaia DR2”. In: Astronomy and Astrophysics 620, A172,
A172. DOI: 10 . 1051 / 0004 - 6361 / 201834150. arXiv: 1810 . 09819
[astro-ph.SR].