barred spiral galaxy
Take an ordinary spiral and run a straight bar of stars right through its middle, so the spiral arms no longer spring from the central bulge but trail off the ends of that bar. The result looks a little like a glowing letter that grew curling tails. That is a barred spiral galaxy — a very common variation on the spiral theme, and the kind our own Milky Way turns out to be.
On the Hubble sequence these occupy the lower prong of the tuning fork, labelled SBa, SBb, SBc, mirroring the unbarred Sa, Sb, Sc spirals. The bar is a long, roughly straight concentration of stars whose orbits have lined up into an elongated shape, sweeping around the galaxy's center as a single rotating structure. It is not a fixed object but a dynamical feature: gravity in a rotating disk is naturally prone to forming bars, and most large spirals — perhaps two-thirds, including the Milky Way — have one, ranging from weak and short to strong and prominent.
Bars matter because they are engines that move material around. A bar acts like a gravitational paddle, channeling gas inward toward the galactic center, where it can feed bursts of star formation or pour onto a central black hole. Bars also redistribute angular momentum, reshape the disk over time, and may build up the central bulge. Studying which galaxies have bars, and how strong, helps astronomers understand how disks evolve and rearrange their own gas without needing an outside collision.
NGC 1300 is a showcase barred spiral: a long, sharp bar of stars cuts across the galaxy, and the two spiral arms peel off cleanly from the bar's two tips rather than from the nucleus itself. Our Milky Way has a more modest bar of the same kind.
A straight bar of stars feeding gas inward — arms trailing from its ends.
A bar is a phase, not a permanent fixture: bars can form, strengthen, and even dissolve over a galaxy's life, so whether a spiral counts as 'barred' can change over cosmic time and can be hard to judge in faint or tilted galaxies.