An article published in “The Astrophysical Journal” reports a study on the variable star U Monocerotis conducted by examining data collected over almost 130 years. A team of researchers led by Laura Vega of Vanderbilt University in Nashville, USA, studied what is in fact a binary system using data that goes back to the observations conducted in 1888 and stored in the archives of the American Association of Variable Star Observers (AAVSO). This is the most comprehensive study ever conducted on a variable star, the largest of the pair, a yellow supergiant whose brightness varies over time.