for what was it developed?
For an infrared survey of the sky.
Spitzer Space Telescope
The launch in January 1983 of the Infrared Astronomical Satellite, jointly developed by the United States, the Netherlands, and the United Kingdom, to conduct the first infrared survey of the sky, whetted the appetites of scientists worldwide for follow-up space missions capitalizing on the rapid improvements in infrared detector technology.

how does a white dwarf form? After the hydrogen-fusing period of a main-sequence star of low or medium mass ends, such a star will expand to a red giant. It the red giant  has insufficient mass to generate the core temperatures required to fuse carbon it forms a planetary nebula. The remaining core is the white dwarf. what metals does it contain? UNANSWERABLE when was it discovered? In 1910. and who discovered it? Henry Norris Russell, Edward Charles Pickering and Williamina Fleming. mention a few works published by the first person? He co-authored a two-volume textbook titled "Astronomy: A Revision of Young’s Manual of Astronomy" . how is the magnetic field of white dwarf? Since 1970 magnetic fields have been discovered in well over 200 white dwarfs, ranging  0.2 T to 100 kT. is it habitable? It has been proposed that white dwarfs with surface temperatures of less than 10,000 Kelvins could harbor a habitable zone at a distance of c. 0.005 to 0.02 AU. does it have any debris around it? Yes, mainly dust clouds. name a place where such dwarfs can be found? The Sirius binary star. are the dwarfs found in any nebula? UNANSWERABLE which telescope was used to discover the dwarf? Spitzer Space Telescope. who developed the telescope? NASA.
wiki:12112540
Spitzer Space Telescope [SEP] History
Earlier infrared observations had been made by both space-based and ground-based observatories. Ground-based observatories have the drawback that at infrared wavelengths or frequencies, both the Earth's atmosphere and the telescope itself will radiate (glow) brightly. Additionally, the atmosphere is opaque at most infrared wavelengths. This necessitates lengthy exposure times and greatly decreases the ability to detect faint objects. It could be compared to trying to observe the stars in the optical at noon from a telescope built out of light bulbs. Previous space observatories (such as IRAS, the Infrared Astronomical Satellite, and ISO, the Infrared Space Observatory) were launched during the 1980s and 1990s and great advances in astronomical technology have been made since then.