2nd LAMOST-Kepler workshop

31 Jul 2017, 09:00 → 3 Aug 2017, 17:35 UTC

Meridian Room (Royal Observatory of Belgium)

Joan Vandekerckhove (Royal Observatory of Belgium), Peter De Cat (Royal Observatory of Belgium)

Book of abstracts 17lamost_Abstracts.pdf

Pictures 17lamost_WorkshopPicture.jpg 17lamost_WorkshopPictureWithNames.jpg

Scientific programme 17lamost_ScientificProgramme.pdf

Slides

• 17lamost_Presentation_CT01_MintsAlexey.pdf
• 17lamost_Presentation_CT02_KahramanAlicavusFiliz.pdf
• 17lamost_Presentation_CT03_FoxMachadoLester.pdf
• 17lamost_Presentation_CT04_UlusoyCeren.pdf
• 17lamost_Presentation_CT05_CatanzaroGiovianni.pdf
• 17lamost_Presentation_CT06_ZongWeikai.pdf
• 17lamost_Presentation_CT07_JinMengqi.pdf
• 17lamost_Presentation_CT08_YuJie.pdf
• 17lamost_Presentation_CT09_AguadoDavid.pdf
• 17lamost_Presentation_CT10_HuangLiChing.pdf
• 17lamost_Presentation_CT11_XiangMaosheng.pdf
• 17lamost_Presentation_CT12_HuangYang.pdf
• 17lamost_Presentation_IR01_ZhangHaotong.pdf
• 17lamost_Presentation_IR02_ShiJianrong.pdf
• 17lamost_Presentation_IR03_LuoAli.pdf
• 17lamost_Presentation_IR04_FeltzingSofia.pdf
• 17lamost_Presentation_IR05_FuJianning.pdf
• 17lamost_Presentation_IR06_MolendaZakowiczJoanna.pdf
• 17lamost_Presentation_IR07_XieJiwei.pdf
• 17lamost_Presentation_IR08_ZhaoYongheng.pdf
• 17lamost_Presentation_IR09_LiuChao.pdf
• 17lamost_Presentation_IT01_RenAnbing.pdf
• 17lamost_Presentation_IT02_FrascaAntonio.pdf
• 17lamost_Presentation_IT03_CorballyChrisGrayRichard.pdf
• 17lamost_Presentation_IT05_ZhangRuyuan.pdf
• 17lamost_Presentation_IT06_NotsuYuta.pdf
• 17lamost_Presentation_IT07_LiHaining.pdf
• 17lamost_Presentation_IT08_MuldersGijs.pdf
• 17lamost_Presentation_IT09_CarlinJeff.pdf
• 17lamost_Presentation_RoundTableDiscussion.pdf
• 17lamost_Presentation_ST01_LampensPatricia.pdf
• 17lamost_Presentation_ST02_VermeylenLore.pdf
• 17lamost_Presentation_ST03_SamadiGhadimAnya.pdf
• 17lamost_Presentation_ST04_SodorAdam.pdf
• 17lamost_Presentation_ST05_MaJun.pdf

Venue 17lamost_Venue.pdf

Monday, 31 July

Registration & Opening ceremony

Convener: Dr Peter De Cat (Royal Observatory of Belgium)

1 Opening words

Some words to welcome the participants of the 2nd LAMOST-Kepler workshop.

Speaker: Dr Peter De Cat (Royal Observatory of Belgium)

10:30 Coffee/Tea break

1 Current Status of the LAMOST and the LAMOST-Kepler Project

2 Current status of the LAMOST Survey Strategy System and 2D pipeline

I will review the current status of LAMOST Survey Strategy System(SSS) and the 2D data reduction pipeline. LAMOST SSS is a pipeline to allocate the fibers to the targets on the sky, it is designed to obtain the best survey efficiency, considering the limitation of the telescope and user requirement(such as the object priority). LAMOST SSS has been working steadily for five years, most of the structures are fixed but minor features are kept updating to make the software more easy to use. LAMOST 2D pipeline is the software to extract 1D spectra from the 2D image. As the pipeline is closely related to the hardware and observation, we have spent a lot of time to understand the hardware characteristics in order to improve the software. I will introduce the recent improvement and the corresponding test results of the 2D pipeline.

Speaker: Dr Haotong Zhang (National Astronomical observatories of China, CAS)

Slides 17lamost_Presentation_IR01_ZhangHaotong.pdf

3 The LAMOST observations

I will introduce the observations of the LAMOST survey, the magnitudes and exposure times of the VB, V, B, M and F plates. I will also present some test observations of medium resolution spectra, and will describe the future medium resolution survey.

Speaker: Prof. Jianrong Shi (National Astronomical Observatories, Chinese Academy of Sciences)

Slides 17lamost_Presentation_IR02_ShiJianrong.pdf

4 The LAMOST data reduction and release (update)

In this talk, a review of the current status of data reduction pipeline of LAMOST and an overview of the updates to the 2D and 1D reduction procedures and the LAMOST stellar parameter pipeline (LASP) will be given. The different versions of the data releases will be compared, the access to the data will be introduced and the details of the data quality will be presented. Stellar parameters are measured for 5 million stars during the first phase of the LAMOST survey. Based on this large database, we performed a serious statistical study regarding the instrumental stability and intrinsic errors. Through machine learning and with the information from multi wavelength bands, we have discovered some interesting outliers in the large stellar parameter data base.

Speaker: Prof. Ali Luo (National Astronomical Observatories, Chinese Academy of Scienes)

Slides 17lamost_Presentation_IR03_LuoAli.pdf

13:00 Lunch break

2.1 The LAMOST as a large spectroscopic survey: Relation with other large spectroscopic surveys

Relation with other large spectroscopic surveys

5 LAMOST compared to future large spectroscopic surveys: application to studies of the Milky Way.

The Milky Way was for a long time regarded as a relatively well-understood and almost static entity with fixed stellar populations. However, starting in around 1990 we have found that the Milky Way stellar structure is very diverse and indeed very dynamic. The European Hipparcos satellite clearly showed how intricately the stars move in the solar neighbourhood. With Gaia’s first full data release coming in 2018 we are sitting on the brink of a revolution in Milky Way studies. However, Gaia on its own is not enough for understanding the nature of the stars or their full 3D movements. For that we need stellar spectra to characterize the stars and to obtain the radial velocities. This can be done from ground-based observations. LAMOST is a major spectroscopic survey encompassing most stellar components of the Milky Way. In this talk I will contrast LAMOST with future large spectroscopic surveys and discuss how the data from these surveys can be combined with Gaia data to deepen our understanding of the Milky Way as a galaxy. I will in particular compare with 4MOST, WEAVE and DESI.

Speaker: Prof. Sofia Feltzing (Lund Observatory)

Slides 17lamost_Presentation_IR04_FeltzingSofia.pdf

6 Ages and distances for LAMOST stars with Gaia parallaxes.

In an effort to unify the spectroscopic data of different surveys for Galactic archaeology purposes we developed and made public our Unified tool for Distance, Age and Mass estimation (UniDAM). This tool is based on a Bayesian method to compute probability density functions of distance modulus, log(age) and mass using spectroscopic parameters (effective temperature, surface gravity and metallicity), infrared photometry (2MASS and AllWISE) and PARSEC isochrones. Here we present the result from UniDAM with Gaia parallaxes incorporated consistently. For over 100,000 LAMOST stars we have Gaia-TGAS parallaxes that we can use to improve distance modulus and log(age) estimates. The use of parallaxes allows us to improve our age and distance estimates substantially - by about 30% in log(age) and about 50% in distance modulus. We also show that further improvements can be expected from further Gaia data releases, bringing log(age) uncertainties to about 0.1 dex and distance modulus uncertainties downto 0.01 mag. We show that for the most distant stars in LAMOST, spectrophotometric estimates of distance modulus will have higher precision even than those from end-of-mission Gaia parallaxes.

Speaker: Dr Alexey Mints (Max Planck Institute for Solar System Research)

Slides 17lamost_Presentation_CT01_MintsAlexey.pdf

7 Interest in LAMOST

Short introduction of my scientific interests and how my work could benefit from LAMOST observations.

Speaker: Dr Patricia Lampens (Koninklijke Sterrenwacht van België)

Slides 17lamost_Presentation_ST01_LampensPatricia.pdf

8 Interest in LAMOST

Short introduction of my scientific interests and how my work could benefit from LAMOST observations.

Speaker: Ms Lore Vermeylen (Royal Observatory of Belgium)

Slides 17lamost_Presentation_ST02_VermeylenLore.pdf

9 Interest in LAMOST

Short introduction of my scientific interests and how my work could benefit from LAMOST observations.

Speaker: Mrs Anya Samadi Ghadim (PhD researcher , university of Tabriz)

Slides 17lamost_Presentation_ST03_SamadiGhadimAnya.pdf

16:00 Coffee/Tea break

2.2 The LAMOST as a large spectroscopic survey: Parameter determination

Parameter determination

10 Analysis of the stellar parameters measured with the LASP code based on the LAMOST-Kepler data

All of the 14 subfields of the Kepler field have been observed at least once with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST, Xinglong Observatory, China) during the 2012-2014 observation seasons. There are 88,628 reduced spectra with SNR$g$ (signal-to-noise ratio in $g$ band) ≥ 6 in the database of the LAMOST-Kepler project (LK-project). By adopting the upgraded version of the LAMOST Stellar Parameter pipeline (LASP), we have determined the atmospheric parameters (Teff, log $g$, and [Fe/H]) and heliocentric radial velocity vrad for 51,406 stars with 61,226 spectra. Compared with atmospheric parameters derived from both high-resolution spectroscopy and asteroseismology method for common stars in Huber et al. (2014), an external calibration of LASP atmospheric parameters was made, leading to the determination of external errors for the giants and dwarfs, respectively. Multiple spectroscopic observations for the same objects were used to estimate the internal uncertainties of the atmospheric parameters as a function of SNRg with the unbiased estimation method. The LASP atmospheric parameters were calibrated based on both the external and internal uncertainties for the giants and dwarfs, respectively. A general statistical analysis of the stellar parameters leads to discovery of 106 candidate metal-poor stars, 9 candidate very metal-poor stars, and 18 candidate high-velocity stars. Fitting formulae were obtained segmentally for both the calibrated atmospheric parameters of the LK-project and the KIC parameters with the common stars. The calibrated atmospheric parameters and radial velocities of the LK-project will be useful for studying stars in the Kepler field.

Speaker: Dr Anbing Ren (Beijing Normal University)

Slides 17lamost_Presentation_IT01_RenAnbing.pdf

11 Activity indicators and stellar parameters of LAMOST-Kepler targets

We present the results of the analysis of LAMOST spectra in the Kepler field with the ROTFIT pipeline. The application of our code to these spectra has allowed us to perform an MK spectral classification and to derive the atmospheric stellar parameters (Teff, logg and [Fe/H]). Moreover, we have also measured the radial velocity of the targets and provide an estimate of the projected rotational velocity for the very rapid rotators in the analyzed sample. The use of low-activity real-star spectra with a negligible rotational broadening as templates has allowed us to detect H-alpha emission also when it is only filling the line core. This emission arises from chromospheres or circumstellar environments, depending on the targeted sources. We have also used the CaII infrared triplet lines as diagnostics of chromospheres or accretion with the same analysis technique. The atmospheric parameters and activity diagnostics for such a large star sample are of fundamental importance for several lines of research. The main results of our work, focusing on the advantages and drawbacks of our technique applied to the LAMOST low-resolution spectra, and on future perspectives will be discussed.

Speaker: Dr Antonio Frasca (INAF - Osservatorio Astrofisico di Catania)

Slides 17lamost_Presentation_IT02_FrascaAntonio.pdf

12 Science with the LAMOST-Kepler spectra based on an analysis with the MKCLASS code

We have reported the accurate two-dimensional spectral classifications obtained with the expert code, MKCLASS, for the first set of Kepler region spectra from LAMOST (Gray et al. 2016). Here we update how these classifications have been used since for science. In particular, we note how they have led to four confirmed lambda Bootis-type stars with pulsation in both p- and g-modes. These have excellent potential in helping solve the lambda-Bootis star enigma. We also give preliminary analysis of the additional 97,641 LAMOST-Kepler spectra observed in 2015.

Speakers: Dr Christopher Corbally (Vatican Observatory), Dr Richard Gray (Department of Physics and Astronomy, Appalachian State University)

Slides 17lamost_Presentation_IT03_CorballyChrisGrayRichard.pdf

Tuesday, 1 August

2.2 The LAMOST as a large spectroscopic survey: Parameter determination

Parameter determination

13 Low-metallicity pulsating stars in the LAMOST DR1

In this study, the results of low-metallicity pulsating stars' research are presented. The stars were selected from the LAMOST DR1 catalogue considering the ranges of [6500:8600] K, [3.6:4.8] dex, and [-2.4:-0.5] dex of effective temperature T_eff, surface gravity logg, and metallicity [Fe/H], respectively. Photometric data of the selected stars were taken from WASP. The stars showing light variation were determined and the frequency analysis was performed. The spectral types, T_eff, and projected rotational velocities vsini of the stars were derived. Additionally, the proper motions of the stars were obtained to check whether the stars belong to the thick disc or halo. As a result of the research, five confirmed, two candidate RR Lyrae stars, and three candidate SX Phe stars were found.

Speaker: Mrs Filiz Kahraman Alicavus (Canakkale Onsekiz Mart University)

Slides 17lamost_Presentation_CT02_KahramanAlicavusFiliz.pdf

14 OAN-SPM spectroscopic observations of a number of stars in the Kepler field: Comparison with LAMOST database.

We present low and medium resolution spectroscopy of a number of stars in the kepler-field-of-view obtained in the past few years during several runs at the Observatorio Astronomico Nacional-San Pedro Martir (OAN-SPM) in Baja California, Mexico. The Boller & Chivens spectrograph installed in the Cassegrain focus of the 2.12-m telescope has been used. The atmospheric parameters of the stars have been computed using the iSpec tool for the analysis of stellar spectra (Blanco-Cuaresma et al. 2014). A comparison between derived physical parameters and those listed in the LAMOST public database is presented.

Speaker: Dr Lester Fox-Machado (Instituto de Astronomia-Universidad Nacional Autonoma de Mexico (UNAM))

Slides 17lamost_Presentation_CT03_FoxMachadoLester.pdf

15 Investigating Oscillations in 16,000 Red Giants using Kepler and LAMOST

The Kepler mission has provided exquisite data to perform ensemble asteroseismic analysis on evolved stars. In this work we systematically characterize the oscillation power excess for 16,136 oscillating red giants, using full-length long-cadence data. We produced a homogeneous catalog of seismic masses, radii, and surface gravities and investigated the properties of the oscillation power excess as a function of seismic mass and metallicity provided by LAMOST. We find that low mass helium-core burning (HeB) stars show the same oscillation amplitude while higher mass HeB stars show lower amplitude compared to RGB stars. We also discovered that the power excess width is an increasing function of stellar mass. We furthermore provide the first evidence for a dependence of the oscillation amplitude and power excess width on metallicity, with metal-rich red giants having higher oscillation and background-granulation amplitudes and narrower excess width. Our asteroseismic stellar properties can be used as reliable distance indicators and age proxies for dating and mapping stellar populations observed by Kepler. It will also provide an excellent opportunity to test asteroseismology using Gaia parallaxes, and lift degeneracies in deriving atmospheric parameters in large spectroscopic surveys such as APOGEE and LAMOST.

Speaker: Mr Jie Yu (University of Sydney)

Slides 17lamost_Presentation_CT08_YuJie.pdf

11:00 Coffee/Tea break

2.3 The LAMOST as a large spectroscopic survey: Ground-based support for space missions

Ground-based support for space missions

16 LAMOST as a ground-based support facility for the space missions

In the era of space missions such as Kepler and K2 which can provide extremely high duty-cycle, high-precision time-series photometric observations for a large number of stars in multiple stellar populations, ground-based spectroscopic observations are needed to characterize hundreds of thousands of stars in a homogeneous way, to support the research of exoplanets, asteroseismology, Galactic archaeology, etc. In 2010, we initiated the LAMOST-Kepler project which aimed at collecting low-resolution spectra for as many objects from the KIC10 catalogue as possible with LAMOST. Since the end of 2015, a number of K2 fields have been observed with LAMOST. In the presentation, I shall introduce the updated progress of the observations of the two projects, summarize the existing scientific work based on the data provided by this project, and discuss the prospects of using LAMOST for the stars in the fields of future missions such as TESS and PLATO.

Speaker: Prof. JIANNING FU (BEIJING NORMAL UNIVESITY)

Slides 17lamost_Presentation_IR05_FuJianning.pdf

17 Analysis of the stellar parameters based on the LAMOST-K2 project data

Massive photometric data of different parts of the galaxy were obtained by covering 16 campaigns around the eclipse through K2, the second phase of the Kepler mission. Unlike the Kepler space telescope K2 mainly focuses on the data of more bright stars. Applying the ground based survey it is way more competent to observe those bright stars. LAMOST, a very influential ground based facility initiated the "LAMOST-K2 " project at the end of 2015. Due to the fact that LAMOST is located at the northern hemisphere, only 8 K2 field can be observed by it. By analyzing the statistics of the LAMOST stellar parameters, some special targets in the LAMOST-K2 field are found: around 65 samples of those have high radial velocity (|Vr| > 300 km/s), 2061 stars were identified as metal poor candidates ([Fe/H]<-1 dex) and 138 stars were recognized as very metal poor candidates ([Fe/H]<-2 dex). Among more than 10 K2 fields, campaign one, which lies in the northern galactic cap, never observed high precise huge photometric data and spectral before. Calibration of the input catalog of K2 has been done by combining the large surface data obtained from the asterseimic method with data of LAMOST atmospheric parameters. Finally by using the stellar parameters and the location in the Hertzsprung-Russel diagram classification of the red giant in K2-C1 field is also done in this work.

Speaker: Mrs Ruyuan Zhang (Beijing normal university)

Slides 17lamost_Presentation_IT05_ZhangRuyuan.pdf

18 Asteroseismic analysis of selected High Amplitude Delta Scuti Candidates in the Kepler field

We present preliminary results on the analysis of the *Kepler* light curve of selected HADS candidates. Initially, *Kepler* data are used to derive frequency content of the variability of the stars. Then, the frequency analysis has been performed for each star using the software package SigSpeC (Reegen, 2007). The period ratios for the modes of highest amplitude are therefore discussed in the Petersen Diagram (Petersen, 1973).

Speaker: Dr Ceren Ulusoy (1.Girne American University, University Drive, PO Box 5, 99428 Karmi Campus, Karaoğlanoğlu, Kyrenia, Turkey 2.College of Graduate Studies, University of South Africa, PO Box 392, Unisa, 0003, Pretoria, South Africa)

Slides 17lamost_Presentation_CT04_UlusoyCeren.pdf

13:00 Lunch Break

3.1 Science with the LAMOST: Stellar astronomy

Stellar astronomy

19 The scientific impact of LAMOST on stellar astronomy.

Since several years, the LAMOST instrument keeps providing us with detailed knowledge about various astrophysical objects. The extra-galactic part of the LAMOST survey allows us to get understanding about the large-scale structure of the Universe. The stellar part of the LAMOST survey provides information about stars in the Milky Way and the nearby galaxies, allowing us to study the structure and evolution of our Galaxy. In this talk, I will focus on the influence of LAMOST on our knowledge and understanding of the properties of stars treated as individual objects as well as of stars which are representative for different samples. Among those, I will discuss stars belonging to globular and open clusters, stars located in selected areas of the sky (e.g. the Kepler and the K2 fields of view), the metal-poor stars, the hyper-velocity stars, and the stars showing pulsations of different types.

Speaker: Dr Joanna Molenda-Zakowicz (University of Wroclaw, Poland)

Slides 17lamost_Presentation_IR06_MolendaZakowiczJoanna.pdf

20 Studies of close binary systems triggered by the LAMOST-Kepler survey

The Kepler four-years space mission and its K2 extension provide photometric time series with unprecedented accuracy. Given the relevance of these data, the introduction of large databases, as homogeneous as possible, collecting important astrophysical parameters such as temperature, gravity and metallicity became necessary. The LAMOST-Kepler project, based on LAMOST spectroscopy of Kepler targets, aims at providing the atmospheric parameters and other basic data for thousands of stars, which fall in the field of view of the Kepler telescope. In the framework of LAMOST-Kepler project, a recent paper by Frasca et al. (2016) focused on the determination of activity indicators, atmospheric parameters, radial and rotational velocities with the code ROTFIT for a sample of about 60000 stars in the Kepler field that were observed with LAMOST from 2011 to 2014. In that paper, a comparison with data from the literature for a few hundred targets allowed the authors to assess the accuracy of the parameters and to identify objects with discrepant values. We know the importance of binary systems as benchmark for a lot of studies in astrophysics, for the determination of masses or as laboratory for evolutionary studies, just to quote some. From the sample of radial velocity by Frasca et al. (2016), two stars (KIC5219533 =HD226766; KIC7599132 = HD180757) have been extracted and observed more carefully with the CAOS spectrograph attached to the 0.91-m telescope at Serra La Nave (Sicily, Italy). The preliminary results of these studies are the subject of this talk.

Speaker: Dr Giovanni Catanzaro (INAF - Catania)

Slides 17lamost_Presentation_CT05_CatanzaroGiovianni.pdf

21 Compact pulsators and Delta Scuti stars with the LAMOST data

The LAMOST survey provides more than seven million spectra of stars which brings key information of basic parameters for those targets, building the largest stellar spectra library now and onward. Precise constraints on a great number of pulsating stars can be given by combining the LAMOST data with the photometric data from ground and space. In this talk, we first present the result of the discovery of four new DA pulsating white dwarf stars from the LAMOST survey. The followed-up observations from ground suggest that the detected pulsations in all these four stars are above the typical S/N~4. We then show the result of a Delta Scuti star, observed by Kepler and LAMOST together, which is possibly a long period binary system as revealed by the time pulsation technique. We finally propose some related projects aiming at mode behaviours (amplitude and frequency modulations) in the compact (white dwarf and hot subdwarf) stars observed by Kepler and LAMOST.

Speaker: Dr Weikai Zong (Department of Astronomy, Beijing Normal University)

Slides 17lamost_Presentation_CT06_ZongWeikai.pdf

15:50 Coffee/Tea break

3.1 Science with the LAMOST: Stellar astronomy

Stellar astronomy

22 Active stars in the Kepler field of view

Superflares are flares that release total energy $10$-$10^{4}$ times greater than that of the biggest solar flares with energy of $\sim10^{32}$ erg. Recent Kepler observations found more than 1000 superflares on a few hundred solar-type stars (e.g., Maehara+2012 Nature). Such superflare stars show quasi-periodic brightness variations with the periods from one to a few tens of days. Rotation period and starspot coverage can be estimated from these brightness variations (Notsu+2013 ApJ). These values are used for discussing detailed properties such as the relation between spot size and flare frequency (Maehara+2017 PASJ), but spectroscopic observations are needed in order to know to what extent estimated values of rotation period and spot sizes are right. Using LAMOST-Kepler Survey spectra, Karoff et al. (2016, Nature Communications) measured intensity of Ca II H&K lines of 5,648 solar-type stars, including 48 superflare stars. The results suggest that there is a good correlation between starspot coverage (from Kepler) and Ca II intensities, and in particular, superflare stars (including slowly-rotating stars) are generally characterized by larger chromospheric emissions than other stars. We are now comparing activity measurements using Ca II H&K lines with measurements using other chromospheric lines in LAMOST spectra (especially Ca II 8542 line). We have also conducted high-dispersion spectroscopic observations of more than 50 superflare stars by using grand-base telescopes like Subaru 8.2m (Notsu+2015a&b PASJ). Similar correlations between starspot coverage and chromosheric emissions can be seen, and we can say that the results from LAMOST (lower resolution but large number of samples) are consistent with those from high-dispersion spectroscopic observations. In this talk, we first briefly summarize statistical study results of superflares from Kepler data, and then overview our spectroscopic studies mentioned above.

Speaker: Mr Yuta Notsu (Kyoto University)

Slides 17lamost_Presentation_IT06_NotsuYuta.pdf

23 Oscillations of Li-rich giant stars in LAMOST-Kepler fields

About 1% of giant stars have been found to have high surface Li abundances, which is unexpected according to the standard stellar evolution models. Asteroseismology may help to understand the internal structures and evolutionary stages of the Li-rich giant stars, if stellar oscillations could be observed. Among 53 candidates of Li-rich giant stars in the LAMOST-Kepler fields, several stars are found to be oscillating. We use asteroseismic analysis to derive detailed information about these stars and constrain their evolution states.

Speaker: Mengqi Jin (department of astronomy of Beijing Normal University)

Slides 17lamost_Presentation_CT07_JinMengqi.pdf

24 Follow-up observations of extremely metal-poor stars identified from SDSS and LAMOST

The most metal-poor stars in the Milky Way witnessed the early phases of the formation of the Galaxy, and have chemical compositions close to the pristine mixture from the Big Bang nucleosynthesis, polluted by one or very few supernovae. Here we present a program to search for and characterize new ultra metal-poor stars in the Galactic halo. These stars are extremely rare: despite significant efforts, only a handful of stars have been identified with a metallicity [Fe/H]< -5 dex. We select candidates from SDSS and LAMOST. Dozens of them have already been observed with the ISIS spectrograph on the 4.2-m William Herschel Telescope. The most interesting objects have been confirmed with the Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) on the 10.4-m Gran Telescopio Canarias (GTC) and the High Resolution Spectrograph (HRS) on the 9.2-m Hobby-Eberly Telescope (HET). Our analysis is highly automated, and based on the FERRE code (Allende Prieto et al. 2006, ApJ, 636, 804).

Speaker: Mr David S. Aguado (Instituto de Astrofísica de Canarias)

Slides 17lamost_Presentation_CT09_AguadoDavid.pdf

Wednesday, 2 August

3.1 Science with the LAMOST: Stellar astronomy

Stellar astronomy

25 Exploring the early evolution of the Milky Way with LAMOST

Surveys of very metal-poor (VMP) stars and follow-up spectroscopic studies for them in the past decade have provided with abundant information on the nature of first stars and early chemical evolution of the Milky Way. LAMOST will soon accomplish its first 5-year spectroscopic survey, and has already observed over 6 million Galactic stars. Such huge database will provide an unprecedented chance to enlarge the currently limited VMP star sample. In 2013, we started to obtain follow-up high-resolution spectroscopy for candidate VMP stars selected from LAMOST database. So far, the project has obtained a success rate of >90% in searching for VMP stars, resulting in chemical abundances for about 230 VMP stars including more than 70 EMP stars and a number of chemically interesting objects such as: (1) Three UMP (ultra metal-poor) stars with [Fe/H] ~ -4.0. One of them is the second UMP turnoff star with Li detection. (2) A dozen Li-rich VMP/EMP stars, including six super Li-rich (A(Li) > +3) stars. They distribute in wide range of evolutionary stage and metallicity (-3.1 < [Fe/H] < -1.7). (3) Other peculiar VMP/EMP stars including r-process enhanced stars, etc. The follow-up project has also observed a number of member stars of halo moving groups and low-alpha abundance halo stars, which would shed light on the merging history of our Galaxy. Statistics of the large sample of VMP stars, together with abundance patterns of these peculiar objects, will be of great interest and importance to probe the early Galaxy and low-mass star evolution with very low metallicities.

Speaker: Dr Haining Li (NAOC)

Slides 17lamost_Presentation_IT07_LiHaining.pdf

26 Physical Properties and Flare Activities of the G-type Eclipsing Binaries from the Kepler Observations

The Kepler space telescope has observed more than 2000 eclipsing binary (EB) systems during its primary mission between 2009 and 2013. According to the effective temperatures measured by Huber et al. (2014), we have selected about 131 systems with G-type primary stars characterized with Teff ~ 5000K-6000K for a statistical study. These classifications are compared to the spectral measurements of LAMOST. Many of the binaries are characterized by the EA (Algol)-type light curves of detached systems. To calculate their spectral types, mass ratio, radius, system incline angles, and orbital distance between the two components in individual EBs, we measured their primary and secondary eclipsing transit depths and effective temperature ratios according to the Kepler data. In some test cases, we can find a best fit of two spectral components from LAMOST spectra. A fraction of the EBs in this sample displayed flare activities. We found 11 systems showing flare events in their Kepler light curves. Then we compare the S-indices of EB systems with and without flare activities. Similar with the single stars with and without flares, systems with flare events usually have a higher S-index than those without. The S-index differences between binary systems are lager than that of single stars, although there are no big S-index difference between EB and single stars.

Speaker: Ms Li-Ching Huang (Institute of Astronomy, National Central University, Taiwan)

Slides 17lamost_Presentation_CT10_HuangLiChing.pdf

27 Interest in LAMOST

Short introduction of my scientific interests and how my work could benefit from LAMOST observations.

Speaker: Dr Ádám Sódor (Konkoly Observatory, Hungarian Academy of Sciences CSFK CSI)

Slides 17lamost_Presentation_ST04_SodorAdam.pdf

28 Interest in LAMOST

Short introduction of my scientific interests and how my work could benefit from LAMOST observations.

Speaker: Prof. Jun Ma (National Astronomical Observatories, Chinese Academy of Sciences)

Slides 17lamost_Presentation_ST05_MaJun.pdf

11:10 Coffee/Tea break

3.2 Science with the LAMOST: Exoplanets

Exoplanets

29 The scientific impact of the LAMOST on exoplanet research

With the discoveries of thousands of planets, the Kepler mission has brought revolutions to the exoplanet researching field, which is advancing from studying individual exoplanets to characterizing planet populations. However, making any reliable statistical inference with a large Kepler planet sample is seriously limited by the lack of accurate stellar parameters for the majority of the targets. With 4000 fibers and 5 degrees of diameter field of view, the LAMOST is uniquely positioned to perform a systematic spectroscopic survey of Kepler target stars. The LAMOST-Kepler survey provides a complete and unbiased sample to perform statistical inference on planet distribution and correlations with host properties, which provides new insights on planet formation and evolution. This talk will review several such statistical studies, showing the impact of LAMOST on the study of Kepler planets. In the future, LAMOST will continue to play such a crucial role in the TESS era.

Speaker: Dr Ji-Wei Xie (Nanjing University)

Slides 17lamost_Presentation_IR07_XieJiwei.pdf

30 Exoplanet Populations as a Function of Stellar Properties

Exoplanets around different type of stars provide a window into the diverse environments in which planets form. The mass and metallicity of exoplanet host stars reflect the conditions in the protoplanetary disks where these planets once formed. The relation between exoplanet populations and their host stars provide strong constraints on the planet formation process. Giant planets occur more frequent around more massive and more metal-rich stars, as predicted by the core-accretion scenario for giant planet formation. Sub-Neptunes, those found in abundance with Kepler, occur around stars with a wide range of metallicities and, curiously, occur more frequently around low-mass M dwarfs than around solar-mass stars, challenging current paradigms in planet formation theory. I will indicate areas where the LAMOST-Kepler project can continue to contribute to characterizing trends between exoplanets and their host stars, in particular in understanding how the population of the smallest exoplanets depends on stellar metallicity.

Speaker: Dr Gijs Mulders (University of Arizona)

Slides 17lamost_Presentation_IT08_MuldersGijs.pdf

12:50 Workshop picture

13:00 Lunch break

14:30 Social Events

19:30 Workshop dinner

Thursday, 3 August

3.3 Science with the LAMOST: Regular surveys

regular surveys

31 The scientific impact of the LAMOST regular surveys

The regular survey of LAMOST began in September 2012 and will end in June 2017 after the completion of 5 observation seasons. In the first regular survey, the projects of the LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) and the LAMOST Extra-GAlactic Survey (LEGAS) have obtained many scientific achievements. The LEGUE project yields a unique data set of more than 6 million stellar spectra and allows one to study the stellar populations, chemical composition, kinematics and structure of the disk and the halo, the gravitational potential and dark matter distribution, the interstellar dust extinction, rare objects (e.g. extremely metal-poor or hyper-velocity stars), and ultimately advance our understanding of the assemblage of the Milky Way and other galaxies and the origin of regularity and diversity of their properties.

Speaker: Prof. Yongheng Zhao (National Astronomical Observatories of China)

Slides 17lamost_Presentation_IR08_ZhaoYongheng.pdf

32 The merging history of the Milky Way as seen by LAMOST

Although the majority of stars observed by LAMOST are brighter than 17th magnitude, the spectroscopic stellar parameters can be used to select more than 10,000 red giant stars in the Milky Way halo from among the more numerous foreground dwarfs. In this talk, I will discuss some efforts to use LAMOST-selected distant RGB stars to probe the merging history of the Galaxy via tidal debris in the halo. I will detail results from our method to statistically detect stellar excess structures (which we call ``SHARDS,'' or Stellar Halo Accretion-Related Debris Structures). This technique uses correlations in velocity-distance phase space, accounting for the LAMOST selection function, to statistically identify stellar excesses relative to a smooth underlying model of Galactic populations. We find that at least 10% of the Milky Way halo stars from LAMOST are part of SHARDS, and that the LAMOST data contain excess substructure over all Galactocentric radii less than 40 kpc, beyond what is expected due to statistical fluctuations and incomplete sampling of a smooth halo. The level of substructure is consistent with the fraction of stars in SHARDS from model halos created entirely from accreted satellites. I will also discuss insights into the nature of the Sagittarius tidal stream gleaned from late-type giants observed by LAMOST, as well as perturbations in the Galactic disk that may be signatures of the effects of dwarf galaxies merging with the Milky Way. Finally, I will speculate about future avenues toward characterizing known tidal substructures via their LAMOST detections, and extending the statistical characterization of SHARDS in the Galactic stellar halo to include velocities and stellar metallicities (and possibly alpha abundances) as additional signatures of the merging history of our Galaxy.

Speaker: Jeff Carlin (LSST)

Slides 17lamost_Presentation_IT09_CarlinJeff.pdf

11:10 Coffee/Tea break

3.3 Science with the LAMOST: Regular surveys

regular surveys

33 Revealing the assemblage and evolution history of the Galactic disk with LAMOST

The talk will introduce our efforts on studying the assemblage and evolution history of the Galactic disk with LAMOST. This includes a brief introduction to the LAMOST value-added catalogues, which contain robust estimates of stellar atmospheric parameters (Teff, logg, [Fe/H]), absolute magnitudes Mv, alpha-element to iron abundance ratio [a/Fe], carbon [C/H] and nitrogen abundance [N/H] yielded by LSP3, as well as interstellar extinction, distance, and kinematic parameters inferred based on the LSP3 parameters. I will then present robust stellar age estimates for millions of LAMOST stars. Finally, I will introduce scientific explorations on the stellar mass distribution, spatial structure and metallicity distribution of the Galactic disk using mono-age stellar populations from LAMOST.

Speaker: Dr Maosheng Xiang (NAOC)

Slides 17lamost_Presentation_CT11_XiangMaosheng.pdf

34 Galactic kinematics and dynamics from the LAMOST Galactic Spectroscopic Surveys (presentation via Skype)

As a milestone of ‘near-field cosmology’ to fulfill the quest for understanding galaxy formation and evolution, the LAMOST Galactic Spectroscopic Surveys have hitherto collected quality spectra of over 7.5M stars, and this number is still increasing at a rate of 1M per annum. Benefitted from this single largest spectroscopic dataset as well as data from other photometric and spectroscopic surveys, significant progresses have been made on the studies of the kinematics and dynamics of the Milky Way, including 1) Accurate estimates the peculiar velocities of the Sun that define the Local Standard of Rest, the starting point of all Galactic kinematic and dynamic studies; 2) A detailed investigation of the bulk motion of nearby disk stars, in 3-dimension for the first time; 3) Accurate determinations of the Galactic rotation curve out from 8 to 100 kpc and the escape velocity curve from 5 to 14 kpc, as well as of the mass surface density in the solar neighborhood. The above newly obtained accurate measurements allow us to derive the mass distribution of the Milky Way with an unprecedented precision, and thus to map out the potential and (dark) matter distribution of our Galaxy. The accurate local dark matter density delivered by these studies bears on the interpretation of any signals that the ongoing dark matter search experiments are expected to detect; 4) Finally, by combining the LAMOST measurements and the first Gaia data release, a sample of nearly ten thousand local main-sequence turn-off stars has been selected, with very accurate 3-dimensional positions and velocities, as well as chemical composition and age information. The sample allows us to study the local disc(s) in multi-dimensional phase space, yielding pivotal information that help constraint the formation and evolution of the Galactic disc(s).

Speaker: Dr Yang Huang (Peking University)

Slides 17lamost_Presentation_CT12_HuangYang.pdf

35 The [α/Fe] distributions of the Galactic disk stars from the spectroscopic survey of LAMOST

The Galactic disk is the main structural component of the Milky Way, but whether there is a sub-structure of the so-called thin- and thick- disks has always been a controversial issue. Using the stellar spectra from the LAMOST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC), we obtained the distributions of [α/Fe] ratios in the R-z space for about 1 800 000 disk stars from the DR4 of LAMOST, connecting with the star kinematics characteristics. The results indicate that the Galactic disk truly consist of two substructures with different [α/Fe] abundances, but there is no a distinct separation between the thin and thick disk (not in metallicity or the [α/Fe] ratios, nor in the space position). Moreover, there is an apparent “warp” in the edge of the Galactic disk.

Speaker: Prof. Ji Li (Department of Space Science and Astronomy, Hebei Normal University)

4 Future of the LAMOST

36 Future plan of LAMOST

LAMOST spectroscopic survey has been operated for 5 years and will be end this year. From 2018, the next 5-year plan, the LAMOST-II survey will be started. My talk will be separated into two parts. Firstly, I will highlight some progresses based on the current LAMOST survey data. In particular, I will talk about the current works on the stellar parameter estimations. Two approaches are used for estimation of the stellar parameters: The Cannon and SLAM. The Cannon uses the LAMOST spectra with APOGEE stellar parameters as the training dataset. It can successfully derive alpha-elements, carbon, and nitrogen abundances as well as the effective temperature, surface gravity, and metallicity for the late type giant stars. As an upgrading method, SLAM uses a machine-learning non-linear forward model to replace the oversampled quadratic model in The Cannon. This allows SLAM to be used in a broader parameter space, not only for giant, but also for dwarf stars. The performance of the two methods are quite similar, namely, reach about 0.04 dex for alpha, carbon, and nitrogen abundance. I will also show some interesting test on estimating primary stellar parameters for binary stars with SLAM. This method will be used to derived elemental abundance from the intermediate resolution spectra in the LAMOST-II survey. In the second part, I will introduce the specific plan of the LAMOST-II survey, which is not simply the extension of the current survey, but include some new things, such as the time-domain survey and the intermediate-resolution spectroscopic survey. I will talk about the details of the new intermediate-resolution spectrograph and also some scientific goals.

Speaker: Dr Chao Liu (NAOC)

Slides 17lamost_Presentation_IR09_LiuChao.pdf

13:20 Lunch break

4 Future of the LAMOST

37 Round table discussions

Slides 17lamost_Presentation_RoundTableDiscussion.pdf

15:50 Coffee/Tea break

5 Workshop summary & Closing ceremony

38 Workshop summary with some thoughts on the future expectations

Workshop summary with some thoughts on the future expectations.

Speaker: Prof. Marc Pinsonneault (Ohio State University, Dept. of Astronomy)

39 Closing words

Some words to thank and to say goodbye to the participants of the 2nd LAMOST-Kepler workshop.

Speaker: Dr Peter De Cat (Royal Observatory of Belgium)