We present B and V time-series photometry of the M31 satellite galaxy Andromeda XXVII (And XXVII) that we observed with the Large Binocular Cameras of the Large Binocular Telescope. In the field of And XXVII we have discovered a total of 90 variables: 89 RR Lyrae stars and 1 Anomalous Cepheid. The average period of the fundamental mode RR Lyrae stars (RRab) (σ = 0.05 day) and the period-amplitude diagram place And XXVII in the class of Oosterhoff I/Intermediate objects. Combining information from the color-magnitude diagram (CMD) and the variable stars, we find evidence for a single old and metal-poor stellar population with [Fe/H] ∼ -1.8 dex and t ∼ 13 Gyr in And XXVII. The spatial distributions of RR Lyrae and red giant branch (RGB) stars give clear indication that And XXVII is a completely disrupted system. This is also supported by the spread observed along the line of sight in the distance to the RR Lyrae stars. The highest concentration of RGB and RR Lyrae stars is found in a circular area of 4 arcmin in radius, centered about 0.°2 in the southeast direction from Richardson et al.'s center coordinates of And XXVII. The CMD of this region is well-defined, with a prominent RGB and 15 RR Lyrae stars (out of the 18 found in the region) tracing a very tight horizontal branch at σ = 0.06 mag (average over 15 stars). We show that And XXVII is a strong candidate building block of the M31 halo.

Cusano, F., Garofalo, A., Clementini, G., Cignoni, M., Muraveva, T., Tessicini, G., et al. (2017). Variable Stars and Stellar Populations in Andromeda XXVII. IV. An Off-centered, Disrupted Galaxy. THE ASTROPHYSICAL JOURNAL, 851(1), 9-23 [10.3847/1538-4357/aa96a5].

Variable Stars and Stellar Populations in Andromeda XXVII. IV. An Off-centered, Disrupted Galaxy

GAROFALO, ALESSIA;Clementini, Gisella;Cignoni, Michele;MURAVEVA, TATIANA;TESTA, VINCENZO;FEDERICI, LUCIANA;
2017

Abstract

We present B and V time-series photometry of the M31 satellite galaxy Andromeda XXVII (And XXVII) that we observed with the Large Binocular Cameras of the Large Binocular Telescope. In the field of And XXVII we have discovered a total of 90 variables: 89 RR Lyrae stars and 1 Anomalous Cepheid. The average period of the fundamental mode RR Lyrae stars (RRab) (σ = 0.05 day) and the period-amplitude diagram place And XXVII in the class of Oosterhoff I/Intermediate objects. Combining information from the color-magnitude diagram (CMD) and the variable stars, we find evidence for a single old and metal-poor stellar population with [Fe/H] ∼ -1.8 dex and t ∼ 13 Gyr in And XXVII. The spatial distributions of RR Lyrae and red giant branch (RGB) stars give clear indication that And XXVII is a completely disrupted system. This is also supported by the spread observed along the line of sight in the distance to the RR Lyrae stars. The highest concentration of RGB and RR Lyrae stars is found in a circular area of 4 arcmin in radius, centered about 0.°2 in the southeast direction from Richardson et al.'s center coordinates of And XXVII. The CMD of this region is well-defined, with a prominent RGB and 15 RR Lyrae stars (out of the 18 found in the region) tracing a very tight horizontal branch at σ = 0.06 mag (average over 15 stars). We show that And XXVII is a strong candidate building block of the M31 halo.
2017
Cusano, F., Garofalo, A., Clementini, G., Cignoni, M., Muraveva, T., Tessicini, G., et al. (2017). Variable Stars and Stellar Populations in Andromeda XXVII. IV. An Off-centered, Disrupted Galaxy. THE ASTROPHYSICAL JOURNAL, 851(1), 9-23 [10.3847/1538-4357/aa96a5].
Cusano, Felice; Garofalo, Alessia; Clementini, Gisella; Cignoni, Michele; Muraveva, Tatiana; Tessicini, Gianni; Testa, Vincenzo; Paris, Diego; Federic...espandi
File in questo prodotto:
Eventuali allegati, non sono esposti

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/629531
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 7
  • ???jsp.display-item.citation.isi??? 3
social impact