From the website, "The SAO/NASA Astrophysics Data System (ADS) is a digital library portal for researchers in astronomy and physics, operated by the Smithsonian Astrophysical Observatory (SAO) under a NASA grant.
The ADS maintains three bibliographic collections containing more than 15 million records covering publications in astronomy and astrophysics, physics, and general science, including all arXiv e-prints. Abstracts and full-text of major astronomy and physics publications are indexed and searchable through the new ADS modern search form as well as a classic search form. A browsable paper form is also available."
Although you can try searching Google for your topic, you will probably find the following web search engines provide more relevant and accurate results.
Preprints are research papers in the beginning stages of the publication process. These initial papers' authors are trying to get their research out to the world. Sometimes their presence on a 'preprint server' allow others to give early feedback so that the writers can edit and change needed processes before submitting to a research journal. Preprint servers are used primarily to set 'priority of discovery' of an author's findings. These servers are a great place to find 'current happening' research.
