Nearly 30,000 Late-Type Main-Sequence Stars with Stellar Age from LAMOST DR5

Jiajun Zhang; Terry D. Oswalt; Jingkun Zhao; Xilong Liang; Xianhao Ye; Gang Zhao

Nearly 30,000 Late-Type Main-Sequence Stars with Stellar Age from LAMOST DR5

Jiajun Zhang, Terry D. Oswalt, Jingkun Zhao, Xilong Liang, Xianhao Ye, Gang Zhao

Physical Sciences

University of Chinese Academy of Sciences

Research output: Contribution to journal › Article › peer-review

Abstract

<p> We construct a sample of nearly 30,000 main-sequence stars with 4500K < Te&fflig; < 5000K and stellar ages estimated by the chromospheric activity−age relation. This sample is used to determine the age distribution in the R − Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the height above the disk midplane. As |Z| increases, the percentage of old stars becomes larger. It is known that scale-height of Galactic disk increases as R increases, which is called &fllig;are. A mild &fllig;are from R &sim; 8.0 to 9.0 kpc in stellar age distribution is found. We also &filig;nd that the velocity dispersion increases with age as con&filig;rmed by previous studies. Finally we present spiral-shaped structures in Z − υZ phase space in three stellar age bins. The spiral is clearly seen in the age bin of [0, 1] Gyr, which suggests that a vertical perturbation to the disk probably took place within the last &sim; 1.0 Gyr.</p>

Original language	American English
Journal	Default journal
State	Published - Nov 26 2020

Keywords

Stellar activity
Stellar ages
Stellar kinematics
Late-type dwarf stars

Disciplines

Astrophysics and Astronomy
Stars, Interstellar Medium and the Galaxy

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title = "Nearly 30,000 Late-Type Main-Sequence Stars with Stellar Age from LAMOST DR5",

abstract = " We construct a sample of nearly 30,000 main-sequence stars with 4500K < Te&fflig; < 5000K and stellar ages estimated by the chromospheric activity−age relation. This sample is used to determine the age distribution in the R − Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the height above the disk midplane. As |Z| increases, the percentage of old stars becomes larger. It is known that scale-height of Galactic disk increases as R increases, which is called &fllig;are. A mild &fllig;are from R &sim; 8.0 to 9.0 kpc in stellar age distribution is found. We also &filig;nd that the velocity dispersion increases with age as con&filig;rmed by previous studies. Finally we present spiral-shaped structures in Z − υZ phase space in three stellar age bins. The spiral is clearly seen in the age bin of [0, 1] Gyr, which suggests that a vertical perturbation to the disk probably took place within the last &sim; 1.0 Gyr.",

keywords = "Stellar activity, Stellar ages, Stellar kinematics, Late-type dwarf stars",

author = "Jiajun Zhang and Oswalt, {Terry D.} and Jingkun Zhao and Xilong Liang and Xianhao Ye and Gang Zhao",

year = "2020",

month = nov,

day = "26",

language = "American English",

journal = "Default journal",

}

TY - JOUR

T1 - Nearly 30,000 Late-Type Main-Sequence Stars with Stellar Age from LAMOST DR5

AU - Zhang, Jiajun

AU - Oswalt, Terry D.

AU - Zhao, Jingkun

AU - Liang, Xilong

AU - Ye, Xianhao

AU - Zhao, Gang

PY - 2020/11/26

Y1 - 2020/11/26

N2 - We construct a sample of nearly 30,000 main-sequence stars with 4500K < Te&fflig; < 5000K and stellar ages estimated by the chromospheric activity−age relation. This sample is used to determine the age distribution in the R − Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the height above the disk midplane. As |Z| increases, the percentage of old stars becomes larger. It is known that scale-height of Galactic disk increases as R increases, which is called &fllig;are. A mild &fllig;are from R &sim; 8.0 to 9.0 kpc in stellar age distribution is found. We also &filig;nd that the velocity dispersion increases with age as con&filig;rmed by previous studies. Finally we present spiral-shaped structures in Z − υZ phase space in three stellar age bins. The spiral is clearly seen in the age bin of [0, 1] Gyr, which suggests that a vertical perturbation to the disk probably took place within the last &sim; 1.0 Gyr.

AB - We construct a sample of nearly 30,000 main-sequence stars with 4500K < Te&fflig; < 5000K and stellar ages estimated by the chromospheric activity−age relation. This sample is used to determine the age distribution in the R − Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the height above the disk midplane. As |Z| increases, the percentage of old stars becomes larger. It is known that scale-height of Galactic disk increases as R increases, which is called &fllig;are. A mild &fllig;are from R &sim; 8.0 to 9.0 kpc in stellar age distribution is found. We also &filig;nd that the velocity dispersion increases with age as con&filig;rmed by previous studies. Finally we present spiral-shaped structures in Z − υZ phase space in three stellar age bins. The spiral is clearly seen in the age bin of [0, 1] Gyr, which suggests that a vertical perturbation to the disk probably took place within the last &sim; 1.0 Gyr.

KW - Stellar activity

KW - Stellar ages

KW - Stellar kinematics

KW - Late-type dwarf stars

UR - https://commons.erau.edu/publication/1493

M3 - Article

JO - Default journal

JF - Default journal

ER -

Nearly 30,000 Late-Type Main-Sequence Stars with Stellar Age from LAMOST DR5

Abstract

Keywords

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