The LAMOST Red Clump Catalog

银河下的郭守敬望远镜 (LAMOST) — 摄影苏晨 Brief introduction to red clump (RC) star

NGC 7789 Clump – can be used to determine distance of cluster

Cannon 1970 Brief introduction to red clump (RC) star

Udalski, Stanek and Paczynski 1998 Propose red clump as standard candle with absolute I-band magnitude calibrated with those stars having Hipparcos distances. Measure distance to Galactic center, Galatcic bar’s structure, LMC, SMC. The distance of LMC by RC is shorter 15% than other tracers.

Girardi et al. 1998-2002 The nature of RC: helium-burning phase The population effects (age, [Fe/H]) can’t be ignored for RC’s aboslute magnitude. Brief introduction to red clump (RC) star

Udalski, Stanek and Paczynski 1998 Propose red clump as standard candle with absolute I-band magnitude calibrated with those stars having Hipparcos distances. Measure distance to Galactic center, Galatcic bar’s structure, LMC, SMC. Indicate the distance of LMC is shorter 15% than other tracers.

Girardi et al. 1998-2002 The nature of RC: helium-burning phase The population effects (age, [Fe/H]) can’t be ignored for RC’s aboslute magnitude. Brief introduction to red clump (RC) star

Udalski, Stanek and Paczynski 1998 Propose red clump as standard candle with absolute I-band magnitude calibrated with those stars having Hipparcos distances. Measure distanceMain RCto Galactic Secondary center, Galatcic bar’s structure, LMC,RC SMC. Indicate the distance of LMC is shorter 15% than other tracers.

Girardi et al. 1998-2002 The nature of RC: helium-burning phase The population effects (age, [Fe/H]) can’t be ignored for RC’s aboslute magnitude. Brief introduction to red clump (RC) star Percival et al. 2003 Brief introduction to red clump (RC) star Percival et al. 2003

Grocholski et al. 2002 Brief introduction to red clump (RC) star Both stellar model and observations show:

Ø When the RC age > 2Gyr, the absolute magnitude (I, K) is not sensitive to age. It also slightly depend on the metallicity.

Ø When the RC age < 2Gyr, the sbosulte magnitude (I, K) is sensitive to age.

Brief introduction to red clump (RC) star

How to select filed RC?

(1) Box in Teff/Color – log g diagram (High contamination)

Williams et al. 2013 Brief introduction to red clump (RC) star

How to select filed RC?

(2) Asteroseismic classification

Δ P: median period spacing for l = 1 Bedding et al. 2011 • 50 < Δ P < 90 s: red giant branch stars • 200 < Δ P < 250 s: red clump stars (< 1.8 Msun) • 150 < Δ P < 200 s: secondary red clump stars (> 1.8 Msun)

Determine Δ P for 3326 Kepler red giant stars and thus give evolution state of those stars.

Stello et al. 2013 Brief introduction to red clump (RC) star

How to select filed RC?

(3) Teff-logg diagram for different [Fe/H] slices

Step I: Separate RC and RGB

Bovy et al. 2014 Brief introduction to red clump (RC) star

How to select filed RC?

(3) Teff-logg diagram for different [Fe/H] slices

Step II: separate main and secondary RC Bovy et al. 2014 Brief introduction to red clump (RC) star

How to select filed RC?

(3) Teff-logg diagram for different [Fe/H] slices 80,000 unique RCs have been selected in LAMOST DR2

Huang et al. 2015 Brief introduction to red clump (RC) star

How to select filed RC?

(3) Teff-logg diagram for different [Fe/H] slices 80,000 unique RCs have been selected in LAMOST DR2

Huang et al. 2015 Brief introduction to red clump (RC) star

How to select filed RC?

(3) Teff-logg diagram for different [Fe/H] slices 80,000 unique RCs have been selected in LAMOST DR2

Huang et al. 2015 Brief introduction to red clump (RC) star

How to select filed RC? 80,000 unique RCs have been selected in (3) Teff-logg diagram for different [Fe/H] slices LAMOST DR2

Huang et al. 2016 Brief introduction to red clump (RC) star

How to select filed RC?

(4) HR diagram by Gaia (still within 4 kpc)

Gaia DR2 The LAMOST red clump catalog in DR4

• Using the same method developed by Bovy et al. 2014 & Huang et al. 2015

• With the method, ~ 0.17 (0.15) million RC stars are selected for SNR > 10 (20). The LAMOST red clump catalog in DR4

• Examination of the sample completeness and purity

6100 red giants with classifications by Varad et al. (2016) The LAMOST red clump catalog in DR4

• Examination of the sample completeness and purity

6100 red giants with classifications by Varad et al. (2016) The LAMOST red clump catalog in DR4

• The spatial coverage The LAMOST red clump catalog in DR4

• Mass & age of RC

Martig et al. 2016 Ness et al. 2016 (Cannon) The LAMOST red clump catalog in DR4

• Mass & age of RC • Over 16,000 accurate seismologic mass has been derived by Yu et al. (2018) using Kepler data.

• Over 4000 LAMOST-Kepler common stars with the above mass ate used to derive stellar ages (by PARSEC isochrones assuming η=0.2). The LAMOST red clump catalog in DR4

• Mass & age of RC

Choice of number of PC: Npc = 100 is best The LAMOST red clump catalog in DR4

• Mass & age of RC The LAMOST red clump catalog in DR4

• Validation of the derived stellar ages of RC The LAMOST red clump catalog in DR4

• Applications I: Validation of the parallax estimated by Gaia DR2

39 uas offset Parallax error smaller than 15%

Lindgen et al. 2018

Huang et al. in prep. The LAMOST red clump catalog in DR4

• Applications II: Study the structures of the MW’s disk

Number density distribution of stellar populations with age younger than 5 Gyr The LAMOST red clump catalog in DR4

• Applications III: Study the chemical properties of the MW’s disk The LAMOST red clump catalog in DR4

• Applications IV: Study the kinematical properties of the MW’s disk (We now have very accurate proper motions from the Gaia DR2) Summary

• We have selected out over 150,000 (170,000) main RC stars with SNR > 20 (10) from the LAMOST DR4, with precise distances (better than 10%), chemical abundances ([Fe/H], [α/Fe], [C/H] and [N/H]), masses & ages (better than 30%), and precise 3D velocities (RV from LAMOST and proper motions from Gaia DR2), Huang et al. to be submitted

• This sample could be used to yield an exquisite picture of unprecedented detail of the Galactic disk (e.g. structures, chemical and kinematic properties and their evolutions).