The movement of stars allows the Milky Way to spin around

Very accurate measurements show that the Milky Way's rotation is simpler than we thought. The remarkable result of the most successful ESO device HARPS, shows the constellation of Cepheids falling towards the Sun, due to the nature of the Cepheids constellation itself.

The result was collected by a team of astrophysicists led by Nicolas Nardetto. Since Henrietta Leavitt's discovery of the special nature of Cepheids in 1912, the bright constellation is used as an indication of distance. Combined with velocity measurements, the properties of Cepheids are extremely valuable tools for studying the rotation of our Milky Way galaxy.

Nardetto said: 'The Milky Way's movement and Cepheids are very confusing and have created conflicting opinions in the research community. According to the galaxy's rotation we deserve to live, the Cepheids constellation is' falling 'towards the Sun at about 2 km / s'.

For decades, scientists have debated whether this phenomenon is actually related to the movement of Cepheidss, and therefore, involves the complex rotation of our galaxy; or that is the result of the atmospheric influence of Cepheids itself.

The artist's impression of the Sun's 'neighbor' and its composition in our galaxy, the Milky Way.The illustration shows the position of some bright stars (white) as well as eight stars of the studied Cepheids (blue).After calculating the Milky Way's rotation (red arrow), it seems that the constellation of Cepheids is 'falling' towards the Sun (blue arrow, this is not the true ratio: in fact, speed Blue is less than 100 times the speed around the Milky Way.The very precise measurements of the HARPS device show that the 'falling' phenomenon is caused by the Cepheids constellation itself and is not related to the Milky Way's rotation.The movement shown by the blue arrow is just an illusion.The ratio of the photo to light years.(Photo: ESO).

Nardetto and colleagues observed Cepheids with the HARPS high-precision spectrophotometer, attached to the ESO 3.6-m telescope in La Silla, located on the 2400m high mountain range of the Atacama desert, Chile.HARPS is known for being a very effective planet-hunting tool, but it can also be used to solve complex cases. The ability to determine the speed of rotation - the speed at which an object approaches or moves away from us - is highly priceless. Nardetto said: 'Our observations show that the constellation movement towards us arises from the internal nature of Cepheids'.

Astronomers discovered that the deviation of the measured speed of Cepheids involves chemical elements in the atmosphere of Cepheids. Nardetto concluded: "This result, if generalized to all stars in the Cepheids constellation, shows that the Milky Way's rotation is simpler than we thought, and symmetrical around an axis."

Refer:
Nardetto, N., Stoekl, A., Bersier, D. & Barnes, TG High resolution spectroscopy for Cepheids distance determination.III.Relation between% u03B3-velocities and% u03B3-asymmetries.Astronomy & Astrophysics, (in press)