The VMC Survey - XXIV. Signatures of tidally stripped stellar populations from the inner Small Magellanic Cloud

Abstract

We study the luminosity function of intermediate-age red-clump stars using deep, near-infrared photometric data covering ∼ 20 deg 2 located throughout the central part of the Small Magellanic Cloud (SMC), comprising the main body and the galaxy's eastern wing, based on observations obtained with the VISTA Survey of the Magellanic Clouds (VMC). We identified regions which show a foreground population (∼11.8 ± 2.0 kpc in front of the main body) in the form of a distance bimodality in the redclump distribution. The most likely explanation for the origin of this feature is tidal stripping from the SMC rather than the extended stellar haloes of the Magellanic Clouds and/or tidally stripped stars from the Large Magellanic Cloud. The homogeneous and continuous VMC data trace this feature in the direction of the Magellanic Bridge and, particularly, identify (for the first time) the inner region (∼ 2 -2.5 kpc from the centre) from where the signatures of interactions start becoming evident. This result provides observational evidence of the formation of the Magellanic Bridge from tidally stripped material from the SMC.

The Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE): The Dust Extinction Curve from Red Clump Stars

“…We conclude that the observed offsets in both the SMC and the LMC curves (the latter also noted by DM16) are a result of the significant depth along the line of sight of both galaxies (see Section 3.2). -Dobrzenieckas et al 2016-Dobrzenieckas et al , 2017Scowcroft et al 2016), and with RC stars (Subramanian et al 2017). Our results in Section 4.1 indicating that the SMC has a depth of ∼10 kpc along the line of sight and that the LMC's depth is ∼5 kpc are generally consistent with distances derived from the Cepheids and RR Lyrae studies above.…”

“…We test the sensitivity of our results to the assumed distance modulus in the Appendix since there is a well-known systematic distance variation as a function of position across the SMC. This variation is demonstrated by observations of Cepheid and RR Lyrae variables, supergiants, RC stars, or a combination of these populations (Florsch et al 1981;Caldwell & Coulson 1986;Welch et al 1987;Hatzidimitriou & Hawkins 1989;Gardiner & Hawkins 1991;Gardiner & Hatzidimitriou 1992;Subramanian & Subramaniam 2009Haschke et al 2012;Kapakos & Hatzidimitriou 2012;Nidever et al 2013;Jacyszyn-Dobrzeniecka et al 2016Scowcroft et al 2016;Subramanian et al 2017). Several of these studies conclude that the galaxy is elongated along an axis approximately along our line of sight with a 10 kpc FWHM of the stellar density distribution (Gardiner & Hawkins 1991;Gardiner & Hatzidimitriou 1992;Nidever et al 2013;Jacyszyn-Dobrzeniecka et al 2016;Subramanian et al 2017).…”

Gaia view of a stellar sub-structure in front of the Small Magellanic Cloud

“…We used the peak RC magnitudes (K s 0 ) provided by Subramanian et al (2017) to calculate the (G−K s ) colour and hence M G . From the values listed in Table 1 of Subramanian et al (2017), we calculated the average K s 0 magnitudes for the inner 0-2 • region and 2.…”

“…• 5-4 • region there are faint and bright RC features and hence we calculated the average K s 0 magnitude for the bright and faint RC. We note here that the K s 0 magnitudes provided by Subramanian et al (2017) are in the VISTA system and the K s band used by Ruiz-Dern et al (2018) is in the 2MASS system. Using the (Y − K s ) 0 colour of RC stars in the VISTA system (given in Fig.7 of Subramanian et al 2017) and applying the transformation equations provided by González-Fernández et al (2018), we converted the K s 0 magnitudes in the VISTA system to the 2MASS system.…”

“…A spectroscopic study by Dobbie et al (2014) of Red Giant Branch (RGB) stars beyond 3 • from the SMC centre, in the eastern regions, supports this interpretation. However, due to the limited spatial coverage of the data, Nidever et al (2013), Subramanian et al (2017) and Tatton et al (2020) could not probe this feature beyond 4. • 0 from the SMC centre and assess its physical connection with the MB.…”