# RAVE stars tidally stripped/ejected from *omega Centauri* globular cluster

J.G. Fernández-Trincado, A. C. Robin, K. Vieira, E. Moreno, O. Bienaymé, C.

Reylé, O. Valenzuela, B. Pichardo, F. Robles-Valdez, A. M. M. Martins

► To cite this version:

J.G. Fernández-Trincado, A. C. Robin, K. Vieira, E. Moreno, O. Bienaymé, et al. RAVE stars tidally stripped/ejected from *omega Centauri* globular cluster. Astronomy and Astrophysics - A&A, 2015, 583 (A76), 10.1051/0004-6361/201526575. [hal-01292743](https://hal.science/hal-01292743)

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# RAVE stars tidally stripped or ejected from the ω Centauri globular cluster*,**

J. G. Fernández-Trincado<fnref n="1" />, A. C. Robin<fnref n="1" />, K. Vieira<fnref n="2" />, E. Moreno<fnref n="3" />, O. Bienaymé<fnref n="4" />, C. Reylé<fnref n="1" />, O. Valenzuela<fnref n="3" />, B. Pichardo<fnref n="3" />, F. Robles-Valdez<fnref n="5" />, and A. M. M. Martins<fnref n="1" />

Received 20 May 2015 / Accepted 10 August 2015

## ABSTRACT

Using six-dimensional phase-space information from the Fourth Data release of the RA Dial Velocity Experiment (RAVE) over the range of Galactic longitude 240° < *l* < 360° and *V*<sub>LSR</sub> < −239 km s<sup>−1</sup>, we computed orbits for 329 RAVE stars that were originally selected as chemically and kinematically related to ω Centauri. The orbits were integrated in a Milky-Way-like axisymmetric Galactic potential, ignoring the effects of the dynamical evolution of ω Centauri due to the tidal effects of the Galaxy disk on the cluster along time. We also ignored secular changes in the Milky Way potential over time. In a Monte Carlo scheme, and under the assumption that the stars may have been ejected with velocities greater than the escape velocity (*V*<sub>rel</sub> > *V*<sub>esc,0</sub>) from the cluster, we identified 15 stars as having close encounters with ω Centauri: (i) 8 stars with relative velocities *V*<sub>rel</sub> < 200 km s<sup>−1</sup> may have been ejected ~200 Myr ago from ω Centauri; (ii) another group of 7 stars were identified with high relative velocity *V*<sub>rel</sub> > 200 km s<sup>−1</sup> during close encounters, and it seems unlikely that they were ejected from ω Centauri. We also confirm the link between J131340.4-484714 as a potential member of ω Centauri, and probably ejected ~2.0 Myr ago, with a relative velocity *V*<sub>rel</sub> ~ 80 km s<sup>−1</sup>.

**Key words.** stars: abundances – stars: kinematics and dynamics – Galaxy: structure – globular clusters: individual: ω Centauri

## 1. Introduction

Known as the most massive and luminous globular cluster of the Milky Way halo, ω Centauri also shows unique physical properties in its structure, chemical enrichment, and internal kinematics (Freeman & Rodgers 1975; Norris et al. 1997; Lee et al. 1999; Hughes & Wallerstein 2000; Gnedin et al. 2002; Mizutani et al. 2003; Pancino et al. 2003; Hilker et al. 2004; Bedin et al. 2004; Sollima et al. 2007, 2009; Bellini et al. 2009, 2010; Johnson & Pilachowski 2010; Moriya & Shigeyama 2010; Da Costa 2012). The nature and origin of ω Centauri is still controversial. It has been proposed that ω Centauri is the remnant core of a tidally disrupted satellite galaxy, which was possibly destroyed long ago by the Milky Way (Lee et al. 1999; Majewski et al. 2000; Bekki & Freeman 2003; Mizutani et al. 2003; Ideta & Makino 2004; Tsuchiya et al. 2004; Romano et al. 2007; Sollima et al. 2009), and some recent works suggest that it could have originated from an even more massive system of about 10⁹ M⊙ (Valcarce & Catelan 2011).

In this scenario it is expected that the orbit of such progenitor would have evolved over time because of the interaction with the Milky Way (Tsuchiya et al. 2003; Bekki & Freeman 2003; Zhao 2004; Ideta & Makino 2004) and part of its residual material would be distributed in the Galactic halo. Several efforts have been made, with various degrees of success, to detect the relics of ω Centauri’s progenitor. Among those studies that have explored the surroundings of the cluster, looking for the controversial pair of tidal tails extending from it and reported by Leon et al. (2000), are one showing that the effects of differential reddening as spurious effects on the detection of tidal tails (Law et al. 2003), the spectroscopy survey of 4000 stars selected from the cluster red giant branch done by Da Costa & Coleman (2008), and the more recent photometric survey of RR Lyrae stars over ~50 square degrees around the cluster by Fernández-Trincado et al. (2013, 2015). None of these works found evidence of stellar overdensities beyond the tidal radius of ω Centauri. However, different results are inferred from the photometric analysis of the STREGA survey (Marconi et al. 2014, Structure and Evolution of the Galaxy), whose tracers are mainly variable stars (RR Lyrae and long-period variables) and main-sequence turn-off stars. These authors found evidence of stellar overdensities at ~1° from the cluster in the direction perpendicular to what was explored in the STREGA

<footnote n="1">¹ Institut Utinam, CNRS UMR 6213, Université de Franche-Comté, OSU THETA Franche-Comté-Bourgogne, Observatoire de Besançon, BP 1615, 25010 Besançon Cedex, France
e-mail: jfernandez@obs-besancon.fr</footnote>

<footnote n="2">² Centro de Investigaciones de Astronomía, AP 264, 5101-A Mérida, Venezuela</footnote>

<footnote n="3">³ Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70264, 04510 México D.F., Mexico</footnote>

<footnote n="4">⁴ Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l'Université, 67000 Strasbourg, France</footnote>

<footnote n="5">⁵ Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ap. 70-543, 04510 D.F., México, Mexico</footnote>

<footnote>* Appendix A is available in electronic form at
http://www.aanda.org</footnote>

<footnote>** Full Table A.1 is only available at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/583/A76</footnote>
<figure><img src="image_2.png" /><figcaption>Fig. 2. RAVE stars in the Galactocentric radial velocity ($V_{GRV}$) vs. Galactic longitude space. The top panel refers to RAVE data, the middle and bottom panels refer to Besançon-galaxy model-simulated RAVE data. ω Centauri is shown with the green cross. Majewski et al. (2012) stellar “streams” are plotted with blue symbols. Probable members found in this work are represented by orange symbols and are the same as in Fig. 1 with their size proportional to the probability of close encounter with the cluster (see Sect. 4), and RAVE halo stars having a negligible probability of encountering with ω Centauri are shown with red dots. The black contours show the full RAVE sample and simulations, respectively. The colored contours refer to the Galactic components from the simulation as in Fig. 1. The gray scale refers to the logarithm of the number of stars in it, as indicated by the color bar. (A color version of this figure is available in the online journal.)</figcaption></figure>

as kinematical membership selection and helps us to obtain a sample of 329 stars that is mostly free of contamination by the Galaxy’s thin and thick disks. Given the magnitudes of these stars, we have been able to explore past dynamic links between these RAVE stars and ω Centauri. For these stars we computed orbits using an axisymmetric model of the Galaxy scaling the model of Allen & Santillan (1991). (Gravitational potential details can be seen in Sect. 4.)

### 3. Kinematic contaminants from the Milky Way

To estimate the kinematical contamination in our sample by stars from the Galaxy, we simulated the RAVE data with the Besançon Galaxy model. We used the new version described in Robin et al. (2014) where the thick-disk and halo characterizations have been revised according to SDSS and 2MASS data. Moreover, the kinematics of the different populations is computed using a corrected asymmetric drift formula (Robin et al., in prep.) reliable outside the Galactic plane. The velocity ellipsoid of the halo is assumed to be (131, 106, 85) km s⁻¹ with the major axis pointing toward the Galactic center. To simulate the RAVE data, we ran a simulation for all the directions, and then a subsample of stars was randomly chosen in each magnitude bin in the I filter, containing exactly the same number of stars observed by

RAVE. A full comparison of this new Besançon Galaxy model with RAVE will be presented in a future paper (Robin et al., in prep.).

In Fig. 2, we present a comparison of the radial velocity relative to the Galactic rest-frame ($V_{GRV}$) distribution for the simulated sample and the RAVE data. To obtain $V_{GRV}$, which is simply the star’s radial velocity as seen from the Sun’s location but in a reference frame at rest with the Galaxy, we use the formulation given by Hawkins et al. (2015) and the following equation:

$$V_{GRV} \equiv RV + [U_{\odot} \cos(l) + (V_{\odot} + V_{LSR}) \sin(l)] \cos(b) + W_{\odot} \sin(b). \quad (1)$$

The Besançon Galaxy model reproduces the general kinematics observed in the RAVE data very well, as evidenced by the signal of the disk observed in the sinusoidal-like density path seen in Fig. 2, with a higher density around $l = 270^{\circ}$ and $V_{GRV} \sim -220$ km s⁻¹ (e.g., Hawkins et al. 2015).

Assuming Gaussian velocity distributions and asymmetric drifts for the thin-disk, young/old thick-disk and halo components, stars with $V_{total} > 180$ km s⁻¹ have a high probability of belonging to the halo (see Nissen & Schuster 2010, and references therein). However, in the case of the Besançon Galaxy model (Robin et al. 2014), the velocity distribution of the thick-disk is non-Gaussian with an extended tail toward $V_{total} < 239$ km s⁻¹. Then in our simulated RAVE stars, those
<table><caption>**Table 1.** Derived ejection parameters for the 15 RAVE stars more likely to have close encounters with ω Centauri.</caption><thead><tr><th rowspan="2">RAVEID</th><th colspan="3">Axisymmetric potential</th><th colspan="3">Non-axisymmetric potential</th></tr><tr><th>V<sub>rel</sub><br>km s<sup>-1</sup></th><th>d<sub>avg</sub><br>kpc</th><th>τ<sub>enc</sub><br>Myr</th><th>V<sub>rel</sub><br>km s<sup>-1</sup></th><th>d<sub>avg</sub><br>kpc</th><th>τ<sub>enc</sub><br>Myr</th></tr></thead><tbody><tr><td colspan="7">Encounters with V<sub>rel</sub> &lt; 200 km s<sup>-1</sup></td></tr><tr><td>J131340.4-484714</td><td>75.9</td><td>0.25</td><td>2.4</td><td>79.7</td><td>0.26</td><td>2.1</td></tr><tr><td>J120407.6-073227</td><td>170.3</td><td>2.25</td><td>37.4</td><td>143.2</td><td>2.28</td><td>36.1</td></tr><tr><td>J151658.3-123519</td><td>137.9</td><td>2.3</td><td>35.4</td><td>139.5</td><td>1.88</td><td>32.1</td></tr><tr><td>J143500.9-264337</td><td>108.3</td><td>1.32</td><td>71.4</td><td>108.2</td><td>1.35</td><td>71.1</td></tr><tr><td>J143024.9-085046</td><td>105.6</td><td>2.34</td><td>28.4</td><td>182.7</td><td>2.34</td><td>28.1</td></tr><tr><td>J144618.8-711740</td><td>166.8</td><td>2.89</td><td>88.4</td><td>132.9</td><td>2.87</td><td>97.1</td></tr><tr><td>J144734.5-722018</td><td>77.0</td><td>1.34</td><td>45.4</td><td>187.6</td><td>1.81</td><td>43.1</td></tr><tr><td>J123113.7-194441</td><td>167.8</td><td>2.31</td><td>30.4</td><td>170.4</td><td>2.31</td><td>31.1</td></tr><tr><td colspan="7">Encounters with V<sub>rel</sub> &gt; 200 km s<sup>-1</sup></td></tr><tr><td>J150703.5-112235</td><td>224.7</td><td>2.36</td><td>23.4</td><td>227.9</td><td>2.39</td><td>24.1</td></tr><tr><td>J040133.8-832428</td><td>225.2</td><td>2.34</td><td>29.4</td><td>237.7</td><td>2.34</td><td>29.1</td></tr><tr><td>J144926.4-211745</td><td>200.8</td><td>2.34</td><td>39.4</td><td>229.9</td><td>2.79</td><td>39.0</td></tr><tr><td>J153016.8-214028</td><td>678.0</td><td>2.84</td><td>118.4</td><td>718.6</td><td>3.48</td><td>122.1</td></tr><tr><td>J152554.5-032741</td><td>206.0</td><td>2.84</td><td>48.4</td><td>323.7</td><td>4.02</td><td>57.1</td></tr><tr><td>J124722.9-282260</td><td>207.3</td><td>2.38</td><td>46.4</td><td>208.2</td><td>2.85</td><td>48.1</td></tr><tr><td>J110842.1-715260</td><td>275.0</td><td>1.34</td><td>45.4</td><td>291.5</td><td>1.91</td><td>45.1</td></tr></tbody></table>

with $180 \text{ km s}^{-1} < V_{\text{total}} < 239 \text{ km s}^{-1}$ might belong to the thick-disk population. In this sense, since our selected stars have $V_{\text{LSR}} < -239 \text{ km s}^{-1}$, they are most probably free of thick-disk contamination (and certainly free of the thin-disk one); nonetheless, we could expect halo stars with a preferential retrograde motion in the Galactic longitude $240^{\circ} < l < 360^{\circ}$ explored in this work.

## 4. Orbits in an axisymmetric Galactic model

In this work, we ran $10^5$ pairs of orbits for each RAVE star and ω Centauri cluster pair, using the Monte Carlo scheme<fnref n="1" /> described in Pichardo et al. (2012). For each Monte Carlo set of orbits pairs, the proper motions, radial velocities, and distances, with their respective error bars are used for both the star and the cluster. As initial test, we calculated orbits backward in time over 1 Gyr from the current position and velocity of ω Centauri in a Milky-Way-like axisymmetric Galactic potential (dynamical friction, spiral arms and bar effects are ignored), which is the Allen & Santillan (1991) model (see details in Pichardo et al. 2012), but scaled with the new values $R_0 = 8.3 \text{ kpc}$, $\Theta_0 = 239 \text{ km s}^{-1}$ given by Brunthaler et al. (2011). Each Monte Carlo run employs a different scaled Galactic potential, using the uncertainties in $R_0$ and $\Theta_0$. Then, we calculated the probability<fnref n="2" /> of close encounters in the past, which was defined as: (i) having a minimum approach distance, $d_{\text{min}} < 100 \text{ pc}$ (e.g., Fernández-Trincado et al. 2015), such that during the encounter the RAVE star is within the region of bounded stellar motions of ω Centauri; (ii) having an encounter time, $\tau_{\text{enc}} < 0.2 \text{ Gyr}$, in which the bar shape of the Galactic bulge and its effect on the Galactic orbits may be approximately ignored. The latter assumption is supported by the results in Appendix A. (We verify that the introduction of a bar in our potential, using the prolate bar model of Pichardo et al. 2004, does not change our conclusions significantly for eight of our candidates with relative

<figure><img src="image_3.png" /><figcaption>**Fig. 3.** Orbit projection in the potential axisymmetric for “J131340.4-484714” (blue line) and ω Centauri (red line) in X, Y Galactic coordinates on the Galactic plane. The solar position is $(X_\odot, Y_\odot) = (8.3, 0, 0)$ kpc in $t = 0$ Gyr. The solid curves show the orbits integrated backwards from initial position in $t = 0$ Gyr (open symbols) to $\tau_{\text{enc}} = 0.2$ Gyr (filled symbols) that have a close encounter with $d_{\text{min}} < 100 \text{ pc}$. (A color version of this figure is available in the online journal.)</figcaption></figure>

velocities $V_{\text{rel}} < 200 \text{ km s}^{-1}$ listed in Table 1.) ω Centauri has an orbital period $\tau_{\text{orb}} \sim 0.08-0.12$ Gyr (e.g., Dinescu et al. 1999; Mizutani et al. 2003), thus in $0.2$ Gyr the cluster will have approximately two perigalactic points. To illustrate the orbital behavior in about $0.2$ Gyr, Fig. 3 shows an example of a pair of orbital star clusters for a RAVE star that will have a close encounter ($d_{\text{min}} < 100 \text{ pc}$) with ω Centauri in $\tau_{\text{enc}} \sim 0.2$ Gyr and a relative velocity of $V_{\text{rel}} = 53.6 \text{ km s}^{-1}$. The average-distance star cluster is $d_{\text{avg}} = 0.9 \text{ kpc}$, from $t = 0$ Gyr until the close encounter time ($t = \tau_{\text{enc}}$).

<footnote n="1">¹ Uncertainties are considered as $1\sigma$ variations, and a Gaussian Monte Carlo sampling generates the parameters to compute the present-day positions and velocities of the ω Centauri and RAVE stars.</footnote>

<footnote n="2">² The probability is defined as $\text{Prob} = \text{Number of orbits having close encounters with the cluster}/N_{\text{total}}$, where $N_{\text{total}} = 1 \times 10^5$ Monte Carlo simulations.</footnote>
<figure><img src="image_4.png" /><figcaption>**Fig. 4.** 2D density plot for [X/H] and $V_{\text{GRV}}$ in the Galactic longitude range $240^{\circ} < l < 360^{\circ}$. The orange and red symbols are the same as in Fig. 1. The cyan dots refer to ω Centauri members from Johnson & Pilachowski (2010). (A color version of this figure is available in the online journal.)</figcaption></figure>

For ω Centauri itself, we calculate the orbit, based on the current distance of $5.57 \pm 0.08$ kpc (Navarrete et al. 2015), proper motion $\mu_{\alpha} \cos(\delta) = -5.08 \pm 0.35$ mas yr$^{-1}$ and $\mu_{\delta} = -3.57 \pm 0.34$ mas yr$^{-1}$, radial velocity $232.2 \pm 0.7$ km s$^{-1}$ (Dinescu et al. 1999), and position $\alpha =13h26m47.24s$ and $\delta = -47^{\circ}28'46.5''$ (Harris 1996).

We briefly highlight some limitations of our calculation, since we ignore the effects of (i) dynamical evolution of the cluster and tidal effects on the cluster exerted by the Galactic disk in each orbit; (ii) mass loss. Because ω Centauri was probably more massive in the past (see Bekki & Freeman 2003; Ideta & Makino 2004), this reduces the probabilities we find. We have also ignored secular changes in the Milky Way potential over time (Lind et al. 2015).

**5. Results and discussion**

Within the sample of 329 stars with $V_{\text{LSR}} < -239$ km s$^{-1}$, a group of 15 RAVE stars were identified as having a probable encounter with ω Centauri within 0.2 Gyr at 100 pc distance, and another group of 314 stars as having unprobable (<0.01%) close encounter with ω Centauri with the same distance and time limit.

For those 15 stars with probable encounters, we identified seven with high relative velocities $V_{\text{rel}} > 200$ km s$^{-1}$, for which it is unlikely that they have been ejected from ω Centauri; and eight stars were identified with relative velocities $V_{\text{rel}} < 200$ km s$^{-1}$, which are more likely associated with ω Centauri (both groups of stars are listed Table 1). These stars (8 more likely) have an average Galactic rotation velocity of $V_{\text{LSR}} \sim -280.9 \pm 37.5$ km s$^{-1}$, which is close to that of the ω Centauri, $V_{\text{LSR}} = -265.3 \pm 55.0$ km s$^{-1}$, as computed by us from the cluster's data. The resulting values $U_{\text{LSR}}$, $V_{\text{LSR}}$, and $W_{\text{LSR}}$ for these stars are given in Table A.1, which gives the same parameters for the 314 stars classified as unlikely to have been ejected from ω Centauri.

We identified 314 RAVE stars with unlikely (or null) encounters with ω Centauri occurred within 100 pc. Figure 2 shows that their Galactocentric radial velocity (red symbols) agrees with the kinematics predicted by the Besançon Galaxy model for the halo. Their [Fe/H] and $V_{\text{LSR}}$ agrees with characteristics of the inner Galactic halo (e.g., Dinescu et al. 1999).

Figure 2 shows stellar debris candidates (blue symbols) from Majewski et al. (2012), with a kinematical and chemical pattern linked to ω Centauri. In the same figure, stars in our kinematical and chemical RAVE selection (orange symbols) have retrograde orbits similar to that of ω Centauri, and are kinematically coherent with the Majewski et al. (2012) sample. It is also evident that our 15 RAVE stars candidates with retrograde velocities do not follow the disk kinematics in both Figs. 1 and 2.

We also identified on star in our sample with RAVEID = J131340.4–484714, previously identified beyond the cluster tidal radius by Anguiano et al. (2015) and listed as a potential member of the ω Centauri globular cluster. Under our numerical simulation scheme, we found 3582 orbits for J131340.4–484714 having close encounters with ω Centauri; i.e., our results suggest that the star has been ejected from ω Centauri with an ejection velocity ($V_{\text{ejection}} \sim 80$ km s$^{-1}$). Figure 5 shows that this star could have been ejected approximately ~2.0 Myr ago, following an orbit very close to ω Centauri as is evident in the Fig. 6. This peculiar star could also be a rare “no-escaper”; that is, a star on a stable orbit outside the cluster tidal radius (Ross et al. 1997).

**5.1. Close encounters: star-Cluster**

Figures 5 and 6 show the relative velocity ($V_{\text{rel}}$) distribution for 15 RAVE stars having close encounters in the past, and the average distance ($d_{\text{avg}}$) distribution for the pairs of orbits from $t=0$ Gyr to $t = \tau_{\text{enc}}$, respectively. As is evident in Fig. 5, the vast majority of the close encounters are produced during time intervals less than approximately two times the orbital period of ω Centauri with relative velocities $V_{\text{rel}} < 200$ km s$^{-1}$ (e.g., Lind et al. 2015) in most cases, and closed orbits with low
<figure><img src="image_5.png" /><figcaption>**Fig. 5.** Distribution of relative velocities ($V_{rel}$) during close encounters for the whole integration time, $t = 1$ Gyr (pink histograms), and $t < 0.2$ Gyr (black histograms). (A color version of this figure is available in the online journal.)</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>**Fig. 6.** $d_{avg}$ distributions, defined as the average distance between pairs of orbits through the Galaxy from the present time (or $t = 0$ Gyr) until the close encounter time ($\tau_{enc}$). The pink distribution refers to the whole integration time (1 Gyr), and the black distribution refers to close encounters with relative velocities within 0.2 Gyr and 100 pc distance. (A color version of this figure is available in the online journal.)</figcaption></figure>

values of $d_{avg}$, such that the pairs of orbits (star – cluster) travel with close distances between them (see illustrated example in Fig. 3), i.e., this approach clearly suggests that their orbits are confined to the ω Centauri orbit. Table 1 lists 15 RAVE stars with the more frequent relative velocity ($V_{rel}$), average distance ($d_{avg}$), and encounter time ($\tau_{enc}$) for each Monte Carlo simulation.

The escape velocity of the ω Centauri cluster at the center is about $V_{esc,0} = 60.4$ km s⁻¹, and at the cluster half-mass radius $V_{esc,h} = 44$ km s⁻¹ (e.g., Gnedin et al. 2002). Given the observational errors and relative velocity $V_{rel} > V_{esc,0}$ star-cluster encounters, it seems unlikely that the star has been tidally stripped from the cluster, since this mechanism is not efficient for
<table><caption>**Table 2.** Mock sample from Besançon Galaxy model (Robin et al. 2014).</caption><thead><tr><td>Id</td><td>Number of false positives (N<sub>false</sub>)</td></tr></thead><tbody><tr><td>Mock sample 1</td><td>4 stars</td></tr><tr><td>Mock sample 2</td><td>2 stars</td></tr><tr><td>Mock sample 3</td><td>2 stars</td></tr><tr><td>Mock sample 4</td><td>4 stars</td></tr><tr><td>Mock sample 5</td><td>1 stars</td></tr></tbody></table>

explaining such fast encounters in our simulations. For $V_{rel} > V_{esc,0}$, the star has most possibly been ejected from the cluster, which is explained in some scenarios by binary system interactions and black holes (e.g. Pichardo et al. 2012; Lind et al. 2015, see references therein).

## 5.2. Chemical distribution for probable ω Centauri members

Figure 4 shows $V_{GRV}$ vs. [Al/Fe], [Si/Fe], [Ti/Fe], [Ni/Fe], [Fe/H] and [Mg/Fe] for the 15 RAVE stars (orange symbols) and the whole RAVE sample (in gray bins). The distribution for the 15 stars found to most likely be debris from the ω Centauri progenitor clearly follows the ω Centauri chemical patterns, as observed for member stars within ω Centauri’s tidal radius (e.g., Johnson & Pilachowski 2010, and references therein). The heavy elements (Si and Ti) generally follow the typical enhancement of ~+0.3 dex found in the cluster population, and ω Centauri exhibits a complex history of chemical enrichment with an abundant metal-poor and intermediate population (e.g., Johnson & Pilachowski 2010). The extended enhancement in chemical abundances observed in our sample of 329 RAVE stars is not conclusive for selecting ω Centauri members from RAVE data; however, we have shown on the Toomre diagram of Fig. 1 that these stars follow the halo kinematics. It should be noted that ω Centauri spans ranges in all the analyzed abundance patterns that are similar to those of the Milky Way, so any similarity between these quantities is not very useful for confirming the origin of these stars.

## 5.3. Statistical significance

To establish the statistical significance of our results, we compared the Monte Carlo simulations (see Sect. 4) to five mock samples created using the Besançon Galaxy model (Robin et al. 2014). For each mock sample we chose 329 stars that randomly satisfy the selection criteria defined in Sect. 2, and the RAVE/UCAC4 selection bias (errors in radial velocities, proper motions and distances are added). The number of false positive are listed in Table 2.

We consider a high significance in our detection if

$$ \sigma_{\text{significance}} = N_{\text{true}} - \langle N_{\text{false}} \rangle > 3 \times \sigma_{\text{false}} \quad (2) $$

where $N_{true} = 15$ (see text), and since we have five mock samples from Table 2, we take the average over all the samples ($\langle N_{false} \rangle = 2.6$), obtaining a mean and standard deviation ($\sigma_{false} = 1.2$) for these values. Then, we find a significance $\sigma_{significance} = 10.33$. Therefore, the number of stars reported in the present paper are $\sigma_{significance} > 3 \times \sigma_{false}$ compared to the mock sample. We can conclude that the methodology in Sect. 4 robustly shows that there is a statistically significant population of stars from the RAVE survey that is possibly ejected from ω Centauri.

## 6. Conclusion

We identified eight RAVE stars at galactic longitudes (240° < $l$ < 360°) with [Fe/H] metallicities in the range -2.2 dex < [Fe/H] < -0.7 dex and with Galactic retrograde motion similar to that of ω Centauri, which could have had a close encounter with ω Centauri with a minimum approach $d_{min} < 100$ pc during the last 200 Myr in the past. Our numerical scheme suggests that these stars have been probably ejected from the cluster with a velocity $V_{ejection} < 200$ km s$^{-1}$, and their kinematic connection with ω Centauri makes them good candidates to be part of the predicted sequence of tidal streams in retrograde rotation left behind the cluster over time.

The probabilities we estimated may neglect some physical evolution of the orbit and/or internal structure of the ω Centauri progenitor, but the agreement with other results in the literature supports our conclusion that the eight RAVE stars reported in this study are candidates for being ω Centauri stellar debris.

We have also identified another group of seven stars having close encounters with ω Centauri; however, the high relative velocities $V_{rel} > 200$ km s$^{-1}$ during the encounters make it unlikely that they have been ejected from ω Centauri.

The 314 other stars with retrograde orbits have a negligible probability of close encounters within 100 pc in 0.2 Gyr. We have classified this group of stars as less likely to have ties with ω Centauri. Their chemical distribution and Galactic retrograde rotation are similar to those of the inner Galactic halo.

We have not found an evident external structure beyond the tidal radius of the cluster from RAVE data on Galactic retrograde rotation.

In order to facilitate the reproducibility and reuse of our results, we have made all the orbit simulations in a public repository³ available.

**Acknowledgements.** J.G.F-T is currently supported by Centre National d'Études Spatiales (CNES) through PhD grant 0101973 and the Région de Franche-Comté and by the French Programme National de Cosmologie et Galaxies (PNCG). This research was supported by the Munich Institute for Astro- and Particle Physics (MIAPP) of the DFG cluster of excellence “Origin and Structure of the Universe”. J.G.F-T also thanks James Binney and George Kordopatis for discussions of this work during the “THE NEW MILKY WAY” workshop. F. Robles-Valdez is grateful to DGAPA-UNAM for the postdoctoral grant CJIC/CTIC/0903 and acknowledge the support from the CONACYT (grant 167625). We are grateful to an anonymous referee for a careful reading and many useful comments that significantly improved the final manuscript. Besançon Galaxy model simulations were executed on computers from the UTINAM Institute of the Université de Franche-Comté, supported by the Région de Franche-Comté and Institut des Sciences de l'Université (INSU). Monte Carlo simulations were executed on computers from the Instituto de Astronomía-UNAM, México. Funding for RAVE has been provided by: the Australian Astronomical Observatory, the Leibniz-Institut fuer Astrophysik Potsdam (AIP), the Australian National University, the Australian Research Council, the French National Research Agency, the German Research Foundation (SPP 1177 and SFB 881), the European Research Council (ERC-StG 240271 Galactica), the Istituto Nazionale di Astrofisica at Padova, the Johns Hopkins University, the National Science Foundation of the USA (AST-0908326), the W. M. Keck foundation, the Macquarie University, the Netherlands Research School for Astronomy, the Natural Sciences and Engineering Research Council of Canada, the Slovenian Research Agency, the Swiss National Science Foundation, the Science & Technology Facilities Council of the UK, Opticon, Strasbourg Observatory and the Universities of Groningen, Heidelberg and Sydney. The RAVE web site is at http://www.rave-survey.org

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# Appendix A: Orbits in a non-axisymmetric Galactic model

We also ran the simulations in a non-axisymmetric galactic potential, in order to verify the bar effect in our results. The Galactic model that we considered is the analytical potential presented in Sect. 4, and the non-axisymmetric Galactic potential including a prolate bar given by Pichardo et al. (2004) to the

galactic bar, with a total mass of ~1.6 × 10¹⁰ $M_\odot$ and angular velocity of $\omega_B = 55 \pm 5$ km s⁻¹ kpc⁻¹ (e.g., Pichardo et al. 2012). Using the same considerations as in Sect. 4 to model the orbits of the RAVE stars and $\omega$ Centauri, 10⁵ pairs of orbits were integrated to 0.2 Gyr in the past. Figures A.1 and A.2 show the results to the stars listed in Table 1; the probabilities of close encounters are similar in both Galactic potential, and the bar effects for integration time <0.2 Gyr, do not affect the results presented in this work.

<figure><img src="image_7.png" /><figcaption>Fig. A.1. Relative velocity ($V_{rel}$) distribution for 10⁵ pairs of orbits integrated backward in time over 0.2 Gyr in an axisymmetric (pink histograms) and non-axisymmetric potential (black histograms).</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>Fig. A.2. $d_{avg}$ distribution. The pink and red histograms are the same as in Fig. A.1.</figcaption></figure>
<caption>Table A.1. $\omega$ Centauri candidates selected from RAVE catalog, their abundance ratios, and space velocities.</caption>

<table><thead><tr><th>RAVEID</th><th>α<sub>2000</sub><br>hh:mm:ss</th><th>δ<sub>2000</sub><br>dd:mm:ss</th><th>T<sub>eff</sub><br>(K)</th><th>log g</th><th>T<sub>eff</sub><br>(K)</th><th>log g</th><th>[Al/H]</th><th>[Si/H]</th><th>[Fe/H]</th><th>[Ti/H]</th><th>[Ni/H]</th><th>[Mg/H]</th><th>U<sub>LSR</sub><br>km<sup>-1</sup></th><th>V<sub>LSR</sub><br>km<sup>-1</sup></th><th>W<sub>LSR</sub><br>km<sup>-1</sup></th><th>D<br>kpc</th><th>RV<sup>†</sup><br>km<sup>-1</sup></th><th>flag</th></tr><tr><th></th><th></th><th></th><th></th><th>dex</th><th>dex</th><th>dex</th><th>dex</th><th>dex</th><th>dex</th><th>dex</th><th>dex</th><th>dex</th><th></th><th></th><th></th><th></th><th></th><th></th></tr></thead><tbody><tr><td>J131340.4-484714</td><td>13:13:40.43</td><td>-48:47:13.8</td><td>4516.3</td><td>0.83</td><td>-</td><td>-0.75</td><td>-1.07</td><td>-1.02</td><td>-</td><td>-</td><td>-0.77</td><td>-</td><td>13.3 ± 48.3</td><td>-279.2 ± 41.5</td><td>-25.2 ± 48.1</td><td>4.4 ± 1.1</td><td>220.2 ± 1.1</td><td>3582</td></tr><tr><td>J131340.4-484714</td><td>13:13:40.43</td><td>-48:47:13.8</td><td>4516.3</td><td>0.83</td><td>-</td><td>-0.75</td><td>-1.07</td><td>-1.02</td><td>-</td><td>-</td><td>-0.77</td><td>-</td><td>13.3 ± 48.3</td><td>-279.2 ± 41.5</td><td>-25.2 ± 48.1</td><td>4.4 ± 1.1</td><td>220.2 ± 1.1</td><td>3582</td></tr><tr><td>J120407.6-073227</td><td>12:04:07.64</td><td>-07:32:26.8</td><td>4481.2</td><td>1.32</td><td>-0.43</td><td>-0.7</td><td>-0.71</td><td>-0.29</td><td>-</td><td>-0.52</td><td>-</td><td>-34.5 ± 28.4</td><td>-305.7 ± 53.4</td><td>-15.4 ± 37.8</td><td>2.8 ± 0.6</td><td>160.1 ± 1.0</td><td>1266</td></tr><tr><td>J115168.3-123519</td><td>15:16:58.34</td><td>-12:35:19.3</td><td>4481.3</td><td>1.41</td><td>-0.63</td><td>-0.81</td><td>-1.27</td><td>-0.6</td><td>-</td><td>-0.64</td><td>-</td><td>50.3 ± 25.8</td><td>-246.0 ± 74.2</td><td>-0.0 ± 3.12</td><td>3.4 ± 0.9</td><td>64.9 ± 1.0</td><td>1059</td></tr><tr><td>J153016.8-214028</td><td>15:30:16.81</td><td>-21:40:28.0</td><td>4544.8</td><td>1.05</td><td>-</td><td>-1.15</td><td>-1.33</td><td>-1.59</td><td>-</td><td>-1.38</td><td>-</td><td>-26.9 ± 28.8</td><td>-252.1 ± 51.0</td><td>191.7 ± 30.1</td><td>3.2 ± 0.7</td><td>113.7 ± 0.5</td><td>1009</td></tr><tr><td>J143500.9-264337</td><td>14:35:00.85</td><td>-26:43:36.8</td><td>4313.8</td><td>0.62</td><td>-1.0</td><td>-1.11</td><td>-1.21</td><td>-0.62</td><td>-</td><td>-1.04</td><td>-15.6 ± 21.5</td><td>-268.3 ± 44.6</td><td>-241.1 ± 59.9</td><td>3.4 ± 22.9</td><td>4.9 ± 0.8</td><td>122.5 ± 0.8</td><td>966</td></tr><tr><td>J150703.5-112235</td><td>15:07:03.45</td><td>-21:23:48.7</td><td>4954.3</td><td>1.79</td><td>-0.7</td><td>-1.07</td><td>-0.97</td><td>-</td><td>-0.45</td><td>-</td><td>-40.9 ± 17.3</td><td>-277.8 ± 90.0</td><td>-64.1 ± 21.7</td><td>-2.1 ± 0.5</td><td>-17.0 ± 18.2</td><td>2.1 ± 0.5</td><td>-13.7 ± 2.4</td><td>923</td></tr><tr><td>J040133.8-832428</td><td>04:01:33.83</td><td>-83:24:27.3</td><td>4357.3</td><td>1.19</td><td>-0.33</td><td>-0.47</td><td>-0.9</td><td>-0.59</td><td>-0.59</td><td>-</td><td>-27.3 ± 26.2</td><td>-243.5 ± 32.1</td><td>-35.8 ± 18.6</td><td>1.7 ± 0.5</td><td>15.6 ± 0.8</td><td>148.6 ± 0.7</td><td>902</td></tr><tr><td>J143024.9-085046</td><td>14:30:24.93</td><td>-08:50:45.6</td><td>4629.0</td><td>1.56</td><td>-0.58</td><td>-0.63</td><td>-0.91</td><td>-0.69</td><td>-</td><td>-0.39</td><td>-41.8 ± 20.4</td><td>-334.8 ± 100.4</td><td>-48.9 ± 34.1</td><td>2.6 ± 0.6</td><td>78.1 ± 0.8</td><td>727</td><td>801</td></tr><tr><td>J144926.4-211745</td><td>14:39:26.41</td><td>-21:17:44.7</td><td>4495.0</td><td>1.12</td><td>-0.86</td><td>-0.81</td><td>-0.99</td><td>-0.5</td><td>-</td><td>-0.96</td><td>-15.5 ± 24.4</td><td>-377.8 ± 90.0</td><td>-48.9 ± 34.1</td><td>2.6 ± 0.6</td><td>164.0 ± 0.8</td><td>707</td><td>707</td></tr><tr><td>J144618.8-71740</td><td>14:46:18.81</td><td>-71:17:40.2</td><td>4384.9</td><td>1.27</td><td>-</td><td>-0.75</td><td>-1.22</td><td>-0.86</td><td>-</td><td>-1.13</td><td>-91.6 ± 50.2</td><td>-318.9 ± 50.0</td><td>65.9 ± 28.6</td><td>3.1 ± 0.7</td><td>164.0 ± 0.8</td><td>707</td><td>707</td></tr><tr><td>J152554.5-032741</td><td>15:25:54.50</td><td>-03:27:41.0</td><td>4437.5</td><td>1.32</td><td>-</td><td>-0.64</td><td>-1.09</td><td>-0.69</td><td>-</td><td>-0.48</td><td>-</td><td>12.1 ± 27.6</td><td>-264.6 ± 79.0</td><td>81.2 ± 30.8</td><td>3.5 ± 0.9</td><td>51.4 ± 0.9</td><td>643</td></tr><tr><td>J124722.9-282260</td><td>12:47:22.91</td><td>-28:22:59.8</td><td>4754.8</td><td>2.0</td><td>-1.27</td><td>-1.09</td><td>-1.56</td><td>-1.65</td><td>-</td><td>-1.22</td><td>-</td><td>2.4 ± 33.1</td><td>-295.1 ± 39.7</td><td>59.9 ± 24.6</td><td>1.2 ± 0.3</td><td>241.2 ± 0.6</td><td>635</td></tr><tr><td>J144734.5-722018</td><td>14:47:34.53</td><td>-72:20:17.7</td><td>4285.1</td><td>0.58</td><td>-0.79</td><td>-0.48</td><td>-0.81</td><td>-0.46</td><td>-0.4</td><td>-0.6</td><td>-</td><td>51.3 ± 28.4</td><td>-264.4 ± 26.2</td><td>-27.5 ± 12.5</td><td>2.3 ± 0.5</td><td>235.8 ± 1.1</td><td>577</td></tr><tr><td>J123113.7-194441</td><td>12:31:13.69</td><td>-19:44:41.2</td><td>4609.3</td><td>1.93</td><td>-0.64</td><td>-0.5</td><td>-0.79</td><td>-0.31</td><td>-</td><td>-0.34</td><td>-</td><td>-59.6 ± 36.7</td><td>-257.9 ± 47.1</td><td>12.9 ± 29.0</td><td>2.1 ± 0.6</td><td>158.0 ± 1.1</td><td>569</td></tr><tr><td>J110842.1-715260</td><td>11:08:42.12</td><td>-71:52:59.9</td><td>4386.0</td><td>0.62</td><td>-0.95</td><td>-</td><td>-1.33</td><td>-</td><td>-0.9</td><td>-</td><td>-</td><td>44.7 ± 26.0</td><td>-263.5 ± 12.1</td><td>-64.1 ± 21.7</td><td>-2.1 ± 0.6</td><td>272.7 ± 0.6</td><td>560</td></tr><tr><td>J235750.0-545311</td><td>23:57:50.04</td><td>-54:53:10.5</td><td>4594.4</td><td>1.03</td><td>-0.92</td><td>-0.84</td><td>-1.14</td><td>-0.79</td><td>-0.57</td><td>-0.46</td><td>-</td><td>-2.4 ± 8.3</td><td>-275.8 ± 51.0</td><td>101.4 ± 18.1</td><td>1.8 ± 0.3</td><td>6.4 ± 0.8</td><td>0</td></tr><tr><td>J235019.3-414650</td><td>23:50:19.27</td><td>-41:46:49.6</td><td>4495.4</td><td>0.82</td><td>-</td><td>-1.54</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-289.5 ± 48.4</td><td>-302.8 ± 59.5</td><td>72.4 ± 9.5</td><td>3.8 ± 0.7</td><td>-118.0 ± 1.3</td><td>0</td></tr><tr><td>J235015.5-345223</td><td>23:50:15.53</td><td>-34:52:33.2</td><td>4435.7</td><td>1.03</td><td>-</td><td>-0.58</td><td>-0.83</td><td>-0.39</td><td>-</td><td>-0.38</td><td>-</td><td>48.3 ± 26.2</td><td>-308.0 ± 48.8</td><td>7.2 ± 7.2</td><td>4.4 ± 0.6</td><td>11.9 ± 0.7</td><td>0</td></tr><tr><td>J234626.8-655235</td><td>23:46:26.75</td><td>-65:52:35.0</td><td>4471.4</td><td>1.18</td><td>-0.31</td><td>-0.64</td><td>-0.88</td><td>-0.43</td><td>-</td><td>-0.47</td><td>-</td><td>64.5 ± 12.5</td><td>-262.0 ± 52.6</td><td>132.3 ± 35.8</td><td>2.4 ± 0.5</td><td>56.5 ± 1.1</td><td>0</td></tr><tr><td>J234612.4-645022</td><td>23:46:12.41</td><td>-64:50:21.7</td><td>4750.2</td><td>1.45</td><td>-0.43</td><td>-0.72</td><td>-1.06</td><td>-0.85</td><td>-</td><td>-1.03</td><td>-</td><td>-291.0 ± 70.8</td><td>-441.3 ± 76.9</td><td>-70.6 ± 8.0</td><td>1.2 ± 0.2</td><td>134.7 ± 1.4</td><td>0</td></tr><tr><td>J233519.6-732443</td><td>23:35:19.61</td><td>-73:24:43.1</td><td>4538.8</td><td>0.95</td><td>-</td><td>-0.86</td><td>-1.25</td><td>-0.23</td><td>-</td><td>-1.19</td><td>-</td><td>218.5 ± 31.6</td><td>-299.6 ± 44.8</td><td>242.6 ± 55.4</td><td>2.6 ± 0.4</td><td>114.4 ± 1.2</td><td>0</td></tr><tr><td>J233441.8-614318</td><td>23:34:41.82</td><td>-61:43:18.3</td><td>4769.2</td><td>0.81</td><td>-</td><td>-1.87</td><td>-1.82</td><td>-1.44</td><td>-</td><td>-0.86</td><td>-</td><td>139.0 ± 21.2</td><td>-282.4 ± 58.8</td><td>107.0 ± 40.4</td><td>1.9 ± 0.4</td><td>95.7 ± 0.7</td><td>0</td></tr><tr><td>J233441.8-614318</td><td>23:34:41.82</td><td>-61:43:18.3</td><td>4769.2</td><td>0.81</td><td>-</td><td>-1.87</td><td>-1.82</td><td>-1.44</td><td>-</td><td>-0.86</td><td>-</td><td>39.5 ± 10.8</td><td>-245.4 ± 51.4</td><td>-36.6 ± 19.7</td><td>0.8 ± 0.2</td><td>149.3 ± 0.7</td><td>0</td></tr><tr><td>J233197.3-611755</td><td>23:31:39.72</td><td>-61:17:55.3</td><td>5059.1</td><td>2.3</td><td>-0.25</td><td>-0.48</td><td>-0.73</td><td>-0.37</td><td>-</td><td>-0.5</td><td>-</td><td>-150.3 ± 38.9</td><td>-476.2 ± 91.9</td><td>-98.9 ± 9.1</td><td>3.7 ± 0.7</td><td>78.0 ± 1.1</td><td>0</td></tr><tr><td>J233197.3-611755</td><td>23:31:39.72</td><td>-61:17:55.3</td><td>5059.1</td><td>2.3</td><td>-0.25</td><td>-0.48</td><td>-0.73</td><td>-0.37</td><td>-</td><td>-0.5</td><td>-</td><td>-150.3 ± 38.9</td><td>-476.2 ± 91.9</td><td>-98.9 ± 9.1</td><td>3.7 ± 0.7</td><td>78.0 ± 1.1</td><td>0</td></tr><tr><td>J232222.3-512630</td><td>23:22:22.25</td><td>-51:26:30.0</td><td>4686.7</td><td>1.65</td><td>-0.36</td><td>-0.51</td><td>-0.78</td><td>-0.59</td><td>-</td><td>-0.26</td><td>-</td><td>10.6 ± 17.5</td><td>-261.5 ± 67.1</td><td>-21.3 ± 14.3</td><td>2.0 ± 0.5</td><td>88.9 ± 1.0</td><td>0</td></tr><tr><td>J232207.0-403031</td><td>23:22:07.01</td><td>-40:30:30.6</td><td>4309.8</td><td>0.75</td><td>-</td><td>-1.0</td><td>-0.73</td><td>-0.26</td><td>-0.29</td><td>-</td><td>-0.47</td><td>190.1 ± 27.9</td><td>-293.2 ± 52.9</td><td>24.2 ± 14.8</td><td>1.8 ± 0.3</td><td>70.9 ± 1.5</td><td>0</td></tr><tr><td>J232189.1-581941</td><td>23:18:19.14</td><td>-58:07:35.6</td><td>4688.0</td><td>1.28</td><td>-0.32</td><td>-1.06</td><td>-1.02</td><td>-</td><td>-</td><td>-</td><td>-</td><td>247.5 ± 41.7</td><td>-326.2 ± 67.2</td><td>152.3 ± 51.4</td><td>1.3 ± 0.3</td><td>106.3 ± 0.6</td><td>0</td></tr><tr><td>J232408.6-420736</td><td>23:24:08.57</td><td>-42:07:35.6</td><td>4688.0</td><td>1.28</td><td>-0.32</td><td>-1.06</td><td>-1.02</td><td>-</td><td>-</td><td>-</td><td>-</td><td>0.21</td><td>-150.5 ± 38.9</td><td>-476.2 ± 91.9</td><td>-98.9 ± 9.1</td><td>3.7 ± 0.7</td><td>174.5 ± 0.7</td><td>0</td></tr><tr><td>J234341.6-662560</td><td>23:14:34.64</td><td>-66:25:59.5</td><td>4361.4</td><td>0.58</td><td>-1.02</td><td>-1.08</td><td>-1.01</td><td>-0.93</td><td>-1.23</td><td>-0.98</td><td>-</td><td>-188.5 ± 40.7</td><td>-309.2 ± 38.1</td><td>-126.4 ± 6.7</td><td>2.0 ± 0.3</td><td>147.9 ± 0.4</td><td>0</td></tr><tr><td>J231033.0-555801</td><td>23:10:33.03</td><td>-55:58:01.1</td><td>5012.1</td><td>1.53</td><td>-</td><td>-1.67</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>29.6 ± 12.8</td><td>-371.8 ± 68.0</td><td>62.6 ± 23.1</td><td>1.9 ± 0.3</td><td>76.5 ± 1.9</td><td>0</td></tr><tr><td>J231058.9-670538</td><td>23:09:58.89</td><td>-40:05:37.6</td><td>4672.5</td><td>1.33</td><td>-0.85</td><td>-0.91</td><td>-0.75</td><td>-0.97</td><td>-</td><td>-0.64</td><td>-</td><td>-131.1 ± 49.0</td><td>-304.2 ± 50.3</td><td>-127.7 ± 12.8</td><td>3.6 ± 0.7</td><td>174.5 ± 0.6</td><td>0</td></tr><tr><td>J231819.1-581941</td><td>23:18:19.14</td><td>-58:19:42.3</td><td>4728.6</td><td>1.71</td><td>-0.99</td><td>-1.08</td><td>-1.17</td><td>-1.22</td><td>-</td><td>-0.85</td><td>-</td><td>49.1 ± 30.5</td><td>-450.6 ± 93.1</td><td>-52.16 ± 50.8</td><td>-251.7 ± 50.8</td><td>-155.2 ± 1.6</td><td>0</td></tr><tr><td>J231434.6-662560</td><td>23:14:34.64</td><td>-66:25:59.5</td><td>4361.4</td><td>0.58</td><td>-1.02</td><td>-1.08</td><td>-1.01</td><td>-0.93</td><td>-1.23</td><td>-0.98</td><td>-</td><td>-107.0 ± 29.3</td><td>-298.5 ± 68.8</td><td>-47.4 ± 10.9</td><td>2.3 ± 0.5</td><td>153.1 ± 1.0</td><td>0</td></tr><tr><td>J231033.0-555801</td><td>23:10:33.03</td><td>-55:58:01.1</td><td>5012.1</td><td>1.53</td><td>-</td><td>-1.67</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-65.0 ± 33.8</td><td>-368.4 ± 70.9</td><td>192.3 ± 44.0</td><td>4.7 ± 0.8</td><td>25.2 ± 1.2</td><td>0</td></tr><tr><td>J231819.1-581941</td><td>23:18:19.14</td><td>-58:07:35.6</td><td>4688.0</td><td>1.28</td><td>-0.32</td><td>-1.06</td><td>-1.02</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-1.17</td><td>-276.3 ± 35.7</td><td>-262.5 ± 48.4</td><td>26.7 ± 14.7</td><td>2.4 ± 0.4</td><td>-125.4 ± 0.6</td><td>0</td></tr><tr><td>J232203.9-444957</td><td>22:20:36.38</td><td>-44:49:56.9</td><td>4706.1</td><td>1.72</td><td>-0.81</td><td>-0.57</td><td>-1.23</td><td>-0.73</td><td>-</td><td>-0.79</td><td>-</td><td>-21.2 ± 24.1</td><td>-541.6 ± 124.4</td><td>-102.2 ± 11.0</td><td>2.6 ± 0.6</td><td>113.7 ± 1.0</td><td>0</td></tr><tr><td>J221515.0-690852</td><td>22:15:15.03</td><td>-69:08:51.8</td><td>4380.3</td><td>1.0</td><td>-0.78</td><td>-</td><td>-1.01</td><td>-1.38</td><td>-</td><td>-0.41</td><td>-</td><td>153.0 ± 14.1</td><td>-257.8 ± 39.5</td><td>70.2 ± 35.7</td><td>2.7 ± 0.5</td><td>165.8 ± 1.0</td><td>0</td></tr><tr><td>J221208.4-700905</td><td>22:12:08.42</td><td>-70:09:05.0</td><td>4985.1</td><td>1.92</td><td>-</td><td>-1.33</td><td>-1.65</td><td>-0.83</td><td>-</td><td>-</td><td>-</td><td>-28.7 ± 33.0</td><td>-239.2 ± 42.7</td><td>9.9 ± 23.4</td><td>1.5 ± 0.3</td><td>-171.9 ± 2.0</td><td>0</td></tr><tr><td>J221208.4-700905</td><td>22:12:08.42</td><td>-70:09:05.0</td><td>4985.1</td><td>1.92</td><td>-</td><td>-1.33</td><td>-1.65</td><td>-0.83</td><td>-</td><td>-</td><td>-</td><td>-187.9 ± 20.0</td><td>-251.6 ± 50.8</td><td>-9.7 ± 22.9</td><td>1.7 ± 0.3</td><td>155.2 ± 1.6</td><td>0</td></tr><tr><td>J221208.4-700905</td><td>22:12:08.40</td><td>-70:09:05.0</td><td>4985.1</td><td>1.92</td><td>-</td><td>-1.33</td><td>-1.65</td><td>-0.83</td><td>-</td><td>-</td><td>-</td><td>-188.4 ± 20.9</td><td>-252.7 ± 58.0</td><td>-4.2 ± 2.7</td><td>0.9 ± 0.2</td><td>-6.0 ± 0.6</td><td>0</td></tr><tr><td>J2211513.3-525707</td><td>21:11:51.26</td><td>-52:57:07.3</td><td>4708.1</td><td>1.16</td><td>-</td><td>-1.26</td><td>-1.54</td><td>-1.45</td><td>-</td><td>-</td><td>-</td><td>-227.0 ± 36.2</td><td>-331.2 ± 83.1</td><td>41.3 ± 8.8</td><td>1.5 ± 0.2</td><td>-109.2 ± 0.8</td><td>0</td></tr></tbody></table>

Notes. The last column indicates the number of Monte Carlo samples with close encounters within 0.2 Gyr at less than 100 pc with a relative velocity less than 200 km s⁻¹ at an axisymmetric Galactic potential. (†) Heliocentric radial velocity (RV). Table A.1 is published in its entirety at the CDS.