Service animal Service animals can be of many species and come in many sizes. Dogs, cats, dolphins, miniature horses, monkeys, ducks, ferrets, and parrots have all been trained to perform specific duties of a service animal, though the type of animal that may be registered as a "service animal" may vary depending on legal definitions. The people that can qualify for a service animal can have a range of physical and/or mental disabilities. A "guide animal" is an animal specifically trained to assist visually impaired persons to navigate in public. These animals may be trained to open doors, recognize traffic signals, guide
A-type main-sequence star also occasionally sees Delta Leonis (A4 V) listed as a standard. There are no published A6 V and A8 V standard stars. A-type stars are young (typically few hundred million years old) and many emit infrared (IR) radiation beyond what would be expected from the star alone. This IR excess is attributable to dust emission from a debris disk where planets form. Surveys indicate massive planets commonly form around A-type stars although these planets are difficult to detect using the Doppler spectroscopy method. This is because A-type stars typically rotate very quickly, which makes it difficult to measure the small