A chemical and kinematical analysis of the intermediate-age open cluster IC 166 from APOGEE and Gaia DR2

IC 166 is an intermediate-age open cluster ($\sim 1$ Gyr) which lies in the transition zone of the metallicity gradient in the outer disc. Its location, combined with our very limited knowledge of its salient features, make it an interesting object of study. We present the first high-resolution spectroscopic and precise kinematical analysis of IC 166, which lies in the outer disc with $R_{GC} \sim 12.7$ kpc. High resolution \textit{H}-band spectra were analyzed using observations from the SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. We made use of the Brussels Automatic Stellar Parameter (BACCHUS) code to provide chemical abundances based on a line-by-line approach for up to eight chemical elements (Mg, Si, Ca, Ti, Al, K, Mn and Fe). The $\alpha-$element (Mg, Si, Ca and whenever available Ti) abundances, and their trends with Fe abundances have been analysed for a total of 13 high-likelihood cluster members. No significant abundance scatter was found in any of the chemical species studied. Combining the positional, heliocentric distance, and kinematic information we derive, for the first time, the probable orbit of IC 166 within a Galactic model including a rotating boxy bar, and found that it is likely that IC 166 formed in the Galactic disc, supporting its nature as an unremarkable Galactic open cluster with an orbit bound to the Galactic plane.


INTRODUCTION
Galactic open clusters (OCs) have a wide age range, from 0 to almost 10 Gyr, and they are spread throughout the Galactic disc; therefore, they are widely used to characterize the properties of the Galactic disc, such as the morphology of the spiral arms of the Milky Way (MW) (Bonatto et al. 2006;van den Bergh 2006;Vázquez et al. 2008), the stellar metallicity gradient (e.g., Jacobson et al. 2016;Frinchaboy et al. 2013;Geisler et al. 1997;Janes 1979), the agemetallicity relation in the Galactic disc (Magrini et al. 2009;Salaris et al. 2004;Carraro & Chiosi 1994;Carraro et al. 1998), and the Galactic disc star formation history (de la Fuente Marcos & de la Fuente Marcos 2004). OCs are thus crucial in developing a more comprehensive understanding of the Galactic disc.
OCs are generally considered to be archetypal examples of a simple stellar population (Deng & Xin 2007), because individual member stars of each OC are essentially homogeneous, both in age, dynamically (similar radial velocities and proper motions) and chemically (similar chemical patterns), greatly facilitating our ability to derive global cluster parameters from studying limited samples of stars. However, possible small inhomogeneous chemical patterns in OCs have been recently suggested, though only at the 0.02 dex level (e.g. Hyades; Liu et al. 2016).
IC 166 (l = 130.071 • , b = −0.189 • ) is an intermediateage OC (∼1.0 Gyr, Vallenari et al. 2000;Subramaniam & Bhatt 2007) located in the outer part of the Galactic disc (R GC ≈13 kpc). Previous literature studies of this cluster used mainly photometric and low-resolution spectroscopic data. Detailed photometric studies were carried out by Subramaniam & Bhatt (2007); Vallenari et al. (2000) and Burkhead (1969) in order to estimate its age, extinction, and distance. In addition, Dias et al. (2014Dias et al. ( , 2002; Loktin & Beshenov (2003) and Twarog et al. (1997) have derived proper motions in the IC 166 field. Friel & Janes (1993) and Friel et al. (1989) have estimated the radial velocity and metallicity of IC 166 from low-resolution spectroscopic data. In this work, we will for the first time provide an extensive, detailed investigation of its chemical abundances as well as its orbital parameters.
OCs are continuously influenced by destructive effects such as (1) evaporation (Moyano Loyola & Hurley 2013), where some members reach the escape velocity after intracluster stellar encounters with other members, and/or via interaction with the Galactic tidal field, and (2) close encounters with giant interstellar clouds (Gieles & Renaud 2016). Interactions with giant molecular clouds along their orbit in the Galactic disc have a high probability to eventually disrupt star clusters (Lamers et al. 2005;Gieles et al. 2006;Lamers & Gieles 2006). These effects can lead to the dissolution of a typical open cluster in ∼10 8 years (Friel 2013). Thus, intermediate-age and old OCs (≥1.0 Gyr) are rare by nature and are of great interest (Friel et al. 2014;Donati et al. 2014;Magrini et al. 2015;Tang et al. 2017). As these effects are generally less severe in the outer disc, OCs there have a higher chance of survival, providing a great opportunity to study this part of the Galaxy both chemically and dynamically. Moreover, IC 166 is located close to the region where a break in the metallicity gradient is suggested (between 10 kpc and 13 kpc from the Galactic center; Frinchaboy et al. 2013;Yong et al. 2012;Reddy et al. 2016). Accurate determination of the cluster's metallicity is helpful to constrain the nature of this possible break.
Large scale multi-object spectroscopic surveys, such as the Apache Point Observatory Galactic Evolution Experiment (APOGEE: Majewski et al. 2017) provide a unique opportunity to study a wide gamut of light-/heavy-elements in the H-band in hundreds of thousands of stars in a homogeneous way (García Pérez et al. 2016;Hasselquist et al. 2016;Cunha et al. 2017). In this work, we provide an independent abundance determination of several chemical species in the open cluster IC 166 using the Brussels Automatic Code for Characterizing High accUracy Spectra (BACCHUS: Masseron et al. 2016), and compare them with the Apogee Stellar Parameter and Chemical Abundances Pipeline (ASPCAP: García Pérez et al. 2016).
This paper is organized as follows. Cluster membership selection is described in Section 2. In Section 3 we determine the atmospheric parameters for our selected members. In Section 4 we present our derived chemical abundances. A detailed description of the orbital elements is given in Section 5. We present our conclusions in Section 6.

TARGET SELECTION
The Apache Point Observatory Galactic Evolution Experiment (APOGEE: Majewski et al. 2017) is one of the projects operating as part of the Sloan Digital Sky Survey IV (Abolfathi et al. 2018;Blanton et al. 2017), aiming to characterize the Milky Way Galaxy's formation and evolution through a precise, systematic and large scale kinematic and chemical study. The APOGEE instrument is a near-infrared (λ = 1.51 − 1.70 µm) high resolution (R ≈ 22, 500) multi-object spectrograph (Wilson et al. 2012) mounted at the SDSS 2.5 m tele-scope (Gunn et al. 2006), with a copy now operating in the South at Las Campanas Observatory -the 2.5-meter Irénée du Pont telescope. The APOGEE survey has observed more than 270,000 stars across all of the main components of the Milky Way (Zasowski et al. 2013(Zasowski et al. , 2017, achieving a typical spectral signal to noise ratio (S/N) >100 per pixel. The latest data release (DR14: Abolfathi et al. 2018) includes all of the APOGEE-1 data and APOGEE data taken between July 2014 and July 2016. A number of candidate member stars of the open cluster IC 166 were observed by the APOGEE survey, and their spectra were released for the first time as part of the DR14 (Abolfathi et al. 2018).
We selected a sample of potential stellar members for IC 166 using the following high quality control cuts: 1. Spatial Location: We focus on stars that are located inside half of the tidal radius (r t /2), where r t = 35.19 ± 6.10 pc (Kharchenko et al. 2012). This can minimize Galactic foreground stars. Figure 1 shows the spatial distribution of 21 highest likelihood cluster members inside half of the tidal radius, highlighted with red dots, for our final sample of likely cluster members. Stars with projected distances from the center larger than half of the tidal radius were removed, in order to obtain a cleaner sample, relatively uncontaminated by disc stars.
2. Radial Velocity and Metallicity: We further selected member stars using their radial velocities (RVs). Figure 2 shows the RV versus [Fe/H] distribution of the stars in the APOGEE observation field of IC 166. Clearly, twenty out of twentyone likely cluster members that we selected using only spatial information show a RV peak around −40 km s −1 , except one with much lower RV (≈ −96 km s −1 ). The other 20 cluster members show a mean RV of −40.50 ± 1.66 km s −1 . Applying a 3σ limit, we excluded stars outside of −40.50 ± 3 × 1.66 km s −1 (gray region in Figure  2). Twenty stars were selected as likely members. After the spatial location and RV selection, their membership status is further scrutinized by filtering out all stars failing to meet the metallicity criteria. We adopt the calibrated metallicity from DR14 APOGEE/ASPCAP as a first guess in order to derive a cleaner sample of cluster stars. We identified a metallicity peak at −0.06 dex; thus stars with metallicities differing by more than 0.03 dex from this mean were removed. Fifteen stars were left as likely members.
3. CMD Location: The left panel of Figure 3 shows the 2MASS (K s , J-K s ) Color-Magnitude diagram, for all stars lying inside one half of the tidal radius. Our selected APOGEE sample clearly lies near the red clump, consistent with the red clump observed in the T eff vs. log(g) plane (right panel of Figure 3). Interestingly, Vallenari et al. (2000) also reported a clear red clump in IC 166, but did not find evidence of RGB stars. Two out of the fifteen stars selected previously were located away from the red clump of IC 166. These stars were also removed from further consideration, although isochrones indicate they could well be upper RGB members. There is a small discrepancy in the location of dereddened red clump stars found using the optical photometry and the T ef f vs. log(g) diagram.
Lastly, we examine the newly-measured proper motions from Gaia DR2 (Gaia Collaboration et al. Lindegren et al. 2018) of the APOGEE/IC 166 candidates. Figure 5 shows the proper motion diagram for IC 166. The dashed lines show the estimated mean proper motion value for IC 166. Gaia DR2 reveals that the selected stars in this study exhibit similar proper motions to each other, with a relatively small spread (< 0.2 mas yr −1 ; see Figure 5), which are good enough for a precise orbit predictions of IC 166. Table 1 shows the basic parameters of the stars which satisfy all the criteria previously mentioned, where raw T eff and log(g) have been considered. These 13 stars will be considered as likely members of IC 166 and constitute our final cluster sample.

ATMOSPHERIC PARAMETERS AND ABUNDANCE DETERMINATIONS
For the stars observed with APOGEE and identified as members in §2, atmospheric parameters (T eff , log g, [M/H] and ξ) were determined using the code FERRE (Allende Prieto et al. 2006) that compares theoretical spectra computed from MARCS atmosphere models (Gustafsson et al. 2008;Zamora et al. 2015) using the entire wavelength range, and minimizes the difference with the observed spectrum via a χ 2 minimization. Our synthetic spectra were based on 1D Local Thermodynamic Equilibrium (LTE) model atmospheres calculated with MARCS (Gustafsson et al. 2008). The derived atmospheric parameters are listed in Table 2.  Figure 1: On-sky distribution of the 13 highest likelihood cluster members analyzed in this work (red symbols) and within 17.6 arcmin (half of the tidal radius) of the center (red dashed line). The inner "x" symbol is the center of the cluster. Indicated with black open circles are field stars that were also observed by APOGEE.
The large blue dashed circle shows the tidal radius of the cluster (35.19 arcmin), while the inner green dashed circle shows the core radius of the cluster.
It is important to note that we chose not to estimate the Teff values from any empirical color-temperature relation; this would be highly uncertain due to relatively large and likely differential reddening along the line-of-   Figure 4 displays the main stellar parameters determined from FERRE/MARCS against those computed from ASPCAP/KURUCZ (raw values), overplotted on the PARSEC isochrones (Bressan et al. 2012) with ages of 0.8, 1.0 and 1.2 Gyr. We notice that the raw (not post-calibrated) stellar parameters obtained Small gray points represent stars observed by 2MASS inside of the r core . Red dots represent our potential members observed by APOGEE and black dots the two stars not passing our high quality cuts (see text). Isochrones for 0.8 Gyr (sky-blue line), 1.0 Gyr (blue line) and 1.2 Gyr (magenta line) from PARSEC are also plotted.
via ASPCAP/KURUCZ are in fairly good agreement with the stellar parameters derived in this study using FERRE/MARCS. After deriving the stellar parameters we used the code BACCHUS (see Masseron et al. 2016;Hawkins et al. 2016) to fit the spectral features of the atomic lines for up to eight chemical elements (Fe, Mg, Al, Si, Ca, Ti, K, and Mn). We did not analyze OH, CN, and CO, because these molecular lines are weak in the typical range of T eff and metallicity for the stars studied in this work, and such an analysis would lead to unreliable abundance results for carbon, nitrogen and oxygen. The line list used in this work is the latest internal DR14 atomic/molecular line list (linelist.20150714: Holtzmman et al. in preparation). For each atomic line, the abundance determination proceeded in the same fashion as described in Hawkins et al. (2016), i.e., we computed spectrum synthesis, using the full set of atomic lines to find the local continuum level via a linear fit; the local S/N was estimated and the abundances were then determined by comparing the observed spectrum with the set of convolved synthetic spectra for different abundances. The BACCHUS code determines line-by-  (2018) we adopted the χ 2 diagnostic as the most robust abundance determination. The selected atomic lines were then visually inspected to ensure that the spectral fits were adequate. The spectral regions used in our analysis are listed in Table A1.
In this study, we derived the abundances of the elements Mg, Si, Ca and Ti (α-elements); Al and K (light odd-Z elements); and Mn and Fe (iron-peak elements). Our abundances were scaled relative to solar abundances (Asplund et al. 2005), in order to provide a direct comparison with the ASPCAP determinations. As mentioned above, we derived chemical abundances manually for our sample stars using the BACCHUS code and using the stellar parameters obtained with FERRE/MARCS. Line-by-line abundance determinations were done for each element for each studied star (Appendix A). The wavelengths of the selected transitions (in air wavelength) for each element are listed in the second column of Table A1. Both abundances A(X) and the solar scaled abundances are given. The '...' symbol is used to indicate that it was not possible to measure a line due to effects such as saturation, weak line, noise, or blending.
Fe, Mg, and Si are the elements having both stronger and more numerous lines in the APOGEE spectra, with 9, 3 and 14 measured lines, respectively. For potassium, we could only identify one K I line in a few of the stars, which is also the case for Ti. We decided to eliminate from further study the Ti abundances due to large uncertainties. In addition, the derived K abundances should be used with caution. Table 4 shows the average abundances of Mg, Si, Ca, Al, K, Mn and Fe, from our manual analysis against the ASPCAP determinations. These results will be compared below: In general, there is good agreement between the mean abundances obtained manually in this work and the AS-PCAP values with comparable dispersion, except for Mg. For Al it is clear that there is a problem with the ASPCAP abundances in this cluster; these issues will be corrected in DR15.

Uncertainties
The uncertainties of chemical abundances are estimated by perturbing the input stellar parameters. We chose star 2 as a representative of our sample stars. We vary each stellar parameter individually according to it own uncertainty (∆T eff =+50 K, ∆log(g)=+0.20 dex, ∆[Fe/H]=+0.20 dex, ∆ξ=+0.20 km s −1 ) in a similar way as described by Souto et al. (2016), and measure the chemical abundances again.   The differences in chemical abundances measured assuming perturbed stellar parameters and unperturbed ones are listed in Table 5. Overall, the chemical abundance uncertainties caused by stellar parameter uncertainties are around 0.1 dex, with slightly larger uncertainties for Mg and K. Mg is mostly affected by variation of T eff and log g, while K is mostly affected by variation of T eff and [Fe/H].  To compare with our results (see Figure 6), we have assembled (1)  • α-elements: Magnesium, silicon and calcium are generally considered as α-elements, because they are formed by fusion involving α-particles. These elements can be produced in large quantities by Type II supernovae (Samland 1998 • Light odd-Z elements: Potassium is primarily the result of oxygen burning in massive stellar explosions (Clayton 2007), so it is related to α−element formation (Zhang et al. 2006), expelled from Type II supernovae (Samland 1998). Although there is not much observational data for K, the available data indicate that its abundance increases as metallicity decreases. Figure 6 shows that the results from Chen et al. (2000) are shifted to higher abundances with respect to that of Hawkins et al. (2016), probably due to differences in the adopted solar abundances.
Our results follow the expected trend for field stars at this metallicity. Aluminum is formed during carbon burning in massive stars, mostly by the reactions between 26 Mg and excess neutrons (Clayton 2007). The Al abundances may also be changed through the Mg-Al cycle at extremely high temperature, e.g., inside AGB stars (Samland 1998;Arnould et al. 1999). Literature values indicate that the Al abundance decreases as metallicity increases, and it stays relatively constant for metallicity greater than solar. The large dispersion found in the AS-PCAP Al abundance results for IC 166 are not found in the literature for any open cluster, nor in our manual results. As discussed above this is due to problems in the ASPCAP analysis. Four Galac-tic anti-center OCs from Yong et al. (2005), together with IC 166 form a similar [Al/Fe] − [Fe/H] trend as field stars.
• Iron-peak elements: Manganese is thought to form in explosive silicon burning (Woosley & Weaver 1995;Clayton 2007;Battistini & Bensby 2015). Significant amounts of Manganese are produced by both SN type II and SN type Ia (Clayton 2007

OC Metallicity trend around R GC of IC 166
Studies of the Galactic radial metallicity gradient (Friel 1995;Frinchaboy et al. 2013;Jacobson et al. 2016;) are critical to understand the chemical evolution of the Galactic disc. Open clusters are one of the best tracers for this purpose, because they are located along the whole Galactic disc and they provide relatively easily measured chemical and kinematic properties. Most works agree that the metallicity decreases with increasing Galactic radius, at least for older OCs. However, the exact value of the metallicity gradient slope is still unclear (Jacobson et al. 2016;, nor the location of a possible break in the metallicity trend (Yong et al. 2012;Reddy et al. 2016).
In this work, we analyze the high-resolution spectra of IC 166 stars, and derive a metallicity of [Fe/H] = −0.08 ± 0.05 dex. Since IC 166 (R GC ≈12.7 kpc) is located near the possible transition zone around R GC ≈ 10 − 13 kpc Yong et al. 2012;Reddy et al. 2016), it may be enlightening to compare our results to the other high-resolution chemical abundance analysis on OCs near this region. For example, at R GC ≈10.5 kpc, Sales Silva et al. (2016) derived a metallicity of −0.02 ± 0.05 dex for Tombaugh 1; Souto et al. (2016) reported a metallicity of −0.16 ± 0.04 dex for NGC 2420 at R GC ≈11 kpc. More strikingly, Reddy et al. (2016) showed that the metallicities of OCs between 10 − 13 kpc (including about 15 OCs) vary be-tween 0 and −0.4 (their Figure 4). They suggested this region is the transition zone between thin disc OCs and thick disc OCs. Therefore, IC 166, Tombaugh 1, and NGC 2420 safely fit in the metallicity range defined by other OCs in this region. A discussion about the existence of this break requires a large number of OCs at different R GC , which is certainly beyond the scope of this single OC concentrated work. Readers are referred to Yong et al. (2012); Reddy et al. (2016) for discussion about this topic.

[α/Fe] versus [Fe/H]
As noted above, α-elements are formed from reactions with α-particles (He nuclei), which are active in Type II SNe. On the other hand, Fe is generated in SN Ia (although also, in smaller amounts, in SNe II); therefore [α/Fe] is related to the ratio of Type II over Type Ia SNe that have enriched a particular star-forming environment.
Because the main polluters of the ISM in the early stages of galaxy formation are Type II SNe, we see enhanced α-element abundances at low metallicities. After ∼ 1 Gyr, Type Ia SNe start to explode, generating a significant amount of iron-peak elements but insignificant amounts of α-elements, and the iron-peak element fraction in the ISM increases quickly (Bensby et al. 2005); [α/Fe] decreases as the metallicity increases. Figure 7 shows stars from APOGEE DR14 as gray dots. Results from ASPCAP DR13 for five OCs (M67, NGC 7789, NGC 6819, NGC 6791, NGC 188 in green, red, yellow, blue and pink dots, respectively) studied by Linden et al. (2017) are added, and also the results from this study for IC 166 (purple dots). The α-elements in this plot are an average of the elements Mg, Si and Ca. All of the IC 166 stars are close to the expected trend for thin disc stars (with a mean [α/Fe]∼-0.05), although our abundance results are slightly more scattered when compared to the results for the other clusters.
IC 166 falls within the region of low α-sequence. Thus the chemical signatures of IC 166, appear to follow the same abundance trends as thin disc field stars (see Figure 7); very similar to other know disc OCs like NGC 7062, IC1369, FSR 942, FSR 821 and FSR 941 studied in Frinchaboy et al. (2013).

THE ORBIT OF IC 166
In order to estimate for the first time a probable Galactic orbit for IC 166, the positional information of IC 166, (α J2000 , δ J2000 ) = 01 h 46 m , 61 • 23 , was combined with the newly-measured proper motions and parallaxes from Gaia DR2 (Gaia Collaboration et al. 2018;Lindegren et al. 2018) as well as with the existing lineof-sight velocities from the APOGEE survey. There were 13 stars in our sample, which were in the Gaia  Chen et al. (2000) and Battistini & Bensby (2015), respectively. The Galactic anti-center OCs from Carraro et al. (2007) and Yong et al. (2005) are shown as black stars and black pluses, respectively.
DR2 catalogue and had a good parallax signal-to-noise (π/π ω > 3; see Table 3). For the 13 members surveyed by APOGEE (for which the membership is most certain) we estimate the mean proper motion of IC 166 as (µ α , µ δ ) = (-1.429±0.083 , 1.139±0.075) mas yr −1 , a radial velocity of -40.58±1.59 km s −1 , and a median parallax, ( π ± σ π )= (0.18466 ± 0.05095) , distance of 5.415±1.494 kpc, our distance estimated from parallax tend to agree with the mean distance estimated from a Bayesian approach using priors based on an assumed density distribution of the Milky Way (e.g., Bailer-Jones et al. 2018), 4.485±0.89 kpc. It is important to note that our assumed Monte Carlo approach to compute the orbital elements are similars adopting both distance estimates, and therefore do not affect the results presented in this work. For the Galactic model we employ the Galactic dynamic software GravPot16 1 (Fernández-Trincado et al. 2018, in preparation), a semi-analytic, steady-state, three dimensional gravitational potential based on the mass density distributions of the Besançon Galactic model (Robin et al. 2003(Robin et al. , 2012(Robin et al. , 2014, observationally and dynamically constrained. The model is constituted by seven thin disc components, two thick discs, an in-1 https://fernandez-trincado.github.io/GravPot16/ terstellar medium (ISM), a Hernquist stellar halo, a rotating bar component, and is surrounded by a spherical dark matter halo component that fits fairly well the structural and dynamical parameters of the Milky Way to the best we know them. A description of this model and its updated parameters appears in a score of papers (Fernández-Trincado et al. 2016Tang et al. 2017Tang et al. , 2018Libralato et al. 2018).
The Galactic potential is scaled to the Sun's galactocentric distance, 8.3±0.23 kpc, and the local rotation velocity, 239±7 km s 1 (e.g., Brunthaler et al. 2011 (Schönrich et al. 2010). A long list of studies in the literature has presented different ranges for the bar pattern speeds. For our computations, the values Ω bar = 35, 40, 45, and 50 km s −1 kpc −1 are employed. These values are consistent with the recent estimate of Ω bar given by Portail et al. (2017); Monari et al. (2017a,b);Fernández-Trincado et al. (2017b). We consider an angle of φ = 20 • for the present-day orientation of the major axis of the Galactic bar and the Sun-Galactic center line. The total mass of the bar taken in this work is 1.1×10 10 M , which corresponds to the dynamical constraints towards the Milky Way bulge from massless particle simulations (Fernández-Trincado et al. 2017b) and is consistent with  Linden et al. (2017) (M67, NGC 7789, NGC 6819, NGC6791, NGC 188 in green, red, yellow, pink, and cyan dots, respectively) are also shown. A sample of five new OCs (NGC 7062, IC1369, FSR 942, FSR 821, FSR 941 in brown, blue, orange, purlple and white triangles, respectively) studied by Frinchaboy et al. (2013) poorly alpha-enriched. Stars of IC 166 are shown as black "x" symbols. The colored crosses show the mean abundances and the standard deviation for each cluster. the recent estimate given by Portail et al. (2017).
The probable orbit of IC 166 is computed adopting a simple Monte Carlo procedure for different bar pattern speeds as mentioned above. For each of 10 3 simulations, we time-integrated backwards the orbits for 2.5 Gyr under variations of the initial conditions (proper motions, radial velocity, heliocentric distance, Solar position, Solar motion and the velocity of the local standard of rest) according to their estimated errors, where the errors are assumed to follow a Gaussian distribution. The results of these computations are showed in Figure B1. The same figures display the probability densities of the resulting orbits projected on the meridional and equatorial Galactic planes in the non-inertial reference frame where the bar is at rest. The yellow and red colors correspond to more probable regions of the space, which are crossed more frequently by the simulated orbits. The final point of each of these orbits has a very similar position to the current one of IC 166.
The median values of the orbital elements for the 10 3 realizations are listed in Table 6. Uncertainties in the orbital integrations are estimated as the 16th (lower limit) where r apo is the apogalactic distance and r peri the perigalactic distance. We find the orbit of IC 166 lies in the Galactic disc and it appears to be an unremarkable typical Galactic open cluster.

CONCLUSIONS
We have presented the first high resolution spectroscopic observations of the stellar cluster IC 166, which was recently surveyed in the H -band of APOGEE. Based on their sky distribution, radial velocity, metallicity, CMD position and proper motions, we have identified 13 highest likelihood cluster members. We derived for the first time manual abundance determinations for up to 8 chemical species (Mg, Ca, Ti, Si, Al, K, Fe, Mn). High-resolution spectra are consistent with the cluster having a metallicity of [Fe/H]= -0.08±0.05 dex. Isochrone fits indicate that the cluster is about 1.0±0.2 Gyr in age.
The results presented here show the cluster lies in the low-α sequence near the solar neighborhood, i.e., the cluster lies in the locus dominated by the low-α sequence of the canonical thin disc. We also found excellent agreement between our chemical abundances and general Galactic trends from large scale studies.
It is important to note that our manual analysis was able to reduce the dispersion found by APOGEE/ASPCAP pipeline for most of the chemical species studied in this work. The most notable improvement was for [Al/Fe] abundance ratios.
Lastly, numerical integration of the possible orbits of IC 166 shows that the cluster appears to be an unremarkable standard Galactic open cluster with an orbit bound to the Galactic plane. The maximum and min-imum Galactic distance achieved by the cluster as well as its orbital eccentricity suggest star formation at large Galactocentric radii. These results suggest that IC 166 could have formed nearer the solar neighborhood, fully compatible with the majority of known Galactic open clusters at similar metallicity. However, the derived orbital eccentricity (∼ 0.13) of the cluster is found be compatible with thin disc populations, but the maximum height above the plane, Zmax, larger than 1.5 kpc like IC 166 is too high for the thin disc and more compatible with the thick disc. It is important to note that, because the orbital excursions in our simulations are in the external part of the Galaxy (up to 16.5 kpc), it is in a region where the disc of the Milky Way is know to exhibit a significant flare (e.g., Reylé et al. 2009) and warp (Momany et al. 2006;Carraro et al. 2007). Such dynamical behaviour have been also observed in anticenter old open clusters, like Gaia 1 (e.g., Koposov et al. 2017;Koch et al. 2018;Carraro 2018).