We report on the discovery of a luminous blue variable ( LBV ) lying \approx 7 pc in projection from the Quintuplet cluster .
This source , which we call LBV G0.120 - 0.048 , was selected for spectroscopy owing to its detection as a strong source of Paschen- \alpha ( P \alpha ) excess in a recent narrowband imaging survey of the Galactic center region with the Hubble Space Telescope /Near-Infrared Camera and Multi-Object Spectrometer .
The K -band spectrum is similar to that of the Pistol Star and other known LBVs .
The new LBV was previously cataloged as a photometric variable star , exhibiting brightness fluctuations of up to \approx 1 mag between 1994 and 1997 , with significant variability also occurring on month-to-month time scales .
The luminosity of LBV G0.120 - 0.048 , as derived from Two Micron All Sky Survey photometry , is approximately equivalent to that of the Pistol Star .
However , the time-averaged brightness of LBV G0.120 - 0.048 between 1994 and 1997 exceeded that of the Pistol Star ; LBV G0.120 - 0.048 also suffers more extinction , which suggests that it was intrinsically more luminous in the infrared than the Pistol Star between 1994 and 1997 .
P \alpha images reveal a thin circular nebula centered on LBV G0.120 - 0.048 with a physical radius of \approx 0.8 pc .
We suggest that this nebula is a shell of ejected material launched from a discrete eruption that occurred between 5000 and 10,000 years ago .
Because of the very short amount of time that evolved massive stars spend in the LBV phase , and the close proximity of LBV G0.120 - 0.048 to the Quintuplet cluster , we suggest that this object might be coeval with the cluster , and may have once resided within it .