The study about the prop-erties of the Gould Belt
Keun-Hong ParkSeoul National University
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
별과 우주 (Star & Universe) 1999, 11 월호
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
소백산천문대 (Sobaeksan Observatory), 2006
Contents
• Introduction• Targets• Result– Study 1: ISM– Study 2: Abundance
• Summary
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
Introduction
• What is the Gould Belt?– Discovered by Herschel and Gould– Ongoing star forming complex
• 1 kpc-sized flat structure• Inclined about 20° to Galactic Plane• Early-type stars, open clusters, YSOs…
• Several Survey Projects– JCMT Legacy Survey of the Gould Belt Project– The Spitzer survey of interstellar clouds in the Gould Belt– Herschel Gould Belt Survey Project
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
Introduction
• Similar structures are found in extra-galaxies.– M 83 (NGC 5236)– NGC 6946
• The origin of the Gould Belt is not clear.– The stellar feedback effect?– Impact of a high-velocity clouds?– Impact of a dark matter clump?
• Find the clues for the origin in this study
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
Introduction
• Select nearby young open clusters inside the Gould Belt and the Galactic Plane.
• Take the high resolution spectra of the stars in the clusters.– BOES at BOAO• R ~ 45,000
– UVES POP archive data• R ~ 80,000
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
Introduction
• Study 1: ISM–Measure E.W. of interstellar lines in the spectra of
early-type stars and derive column densities.– Find interstellar clouds and their distributions.– Improve our knowledge about the LISM.
• Study 2: Abundance– Derive the stellar atmospheric parameters– Derive the abundance from the metal lines.
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Target
Name l (°) b (°) d (pc)
G.B Name l (°) b (°) d (pc)
G.B
Collinder 359 30 13 249 O Platias 6 205 -6 348 X
IC 4665 31 17 352 O Alessi 12 67 -12 537 X
Stephenson 1 67 16 390 O Roslund 5 71 0 389 X
ASCC 123 105 -4 250 O ASCC 23 168 14 600 X
Collinder 69 195 -12 400 O Stock 10 172 4 380 X
ASCC 21 200 -16 500 O NGC 2264 203 2 667 X
ASCC 20 202 -18 450 O Collinder 97 205 -2 630 X
ASCC 18 202 -18 500 O ASCC 104 55 -2 800 X
Collinder 70 205 -17 387 O
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
IC 2391 270 -7 175 O NGC 6475 356 -5 301 X
ISM
• Targets– IC 2391 – NGC 6475– Collinder 70– IC 4665, Collinder 359, Stephenson 1, Roslund 5
• Lines– Ti II (3383.76 Å)– Ca II (3933.66 Å)– Na I D (5889.95 Å, 5895.92 Å)– K I (7698.96 Å)
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
ISM
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
IC 2391
15km/s
ISM
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
IC 2391
15km/s23km/s
ISM
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
IC 2391 (~ 150 pc)
Ca II Na I
ISM
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
NGC 6475
-3 km/s
ISM
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
NGC 6475
-3 km/s
ISM
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
NGC 6475 (~300pc)
Ca II Na I
ISM
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
Collinder 70
25 km/s11 km/s
ISM
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
IC 4665, Collinder 359
-15 km/s
ISM
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Stephenson 1, Roslund 5
-15 km/s
Abundance
• Almost observed target is early-type star.– A few metal lines -> detailed analysis is impossible– Consider non-LTE effect
• More study is needed in this part.
• Non-LTE effect is ignored in follow examples.
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Star Cluster Mag.(V) Sp_Type Exp. (s)
HD 175538 Stephen-son 1 7.6 B9 3600 * 2
HD 191530 Roslund 5 7.9 B9II 3600 * 2
Abundance• T, gravity : H line profile fitting
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
star Hγ Hδ Hε Tlog g
HD17553
8
12750
4.25
HD19153
0
12500
3.75
Abundance• Mg
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
star Mg lines [X/H]
HD17553
8-0.50
HD19153
00.00
Abundance• Si
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
star Si lines [X/H]
HD17553
8-0.50
HD19153
00.00
Abundance• O
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement
star O lines [X/H]
HD17553
80.25
HD19153
00.25
Summary
• Gould Belt is one of the most interesting structure• However, origin of it is not investigated.• Aim to find the clues of the origin from this study• Found the ISM clouds and their distributions from
the spectra of early-type spectra.• Try to derive the abundance of the stars in each clus-
ter, and to find the existence of the difference be-tween the Gould Belt members and non-members.
Work shop on Stars, Planets, and Life: Current Issues on Stellar AstronomyIn Honor of Professor Sang-Gak Lee’s Retirement