SFRs

SFRs, or star formation rates, quantify how rapidly a galaxy forms new stars. The rate is commonly expressed in solar masses per year (M⊙ yr⁻¹). SFRs are inferred from tracers of recent star formation, including ultraviolet emission from young massive stars, Balmer line luminosities such as Hα, and the thermal emission from dust at infrared wavelengths. Each tracer has advantages and caveats: UV and Hα are sensitive to dust extinction, while infrared traces dust-enshrouded regions. Combining indicators yields more robust estimates. Specific star formation rate (sSFR) normalizes the SFR by a galaxy’s stellar mass, enabling comparisons across populations. SFRs correlate with gas content and metallicity, and they evolve with cosmic time, with the global star formation rate density peaking around redshift z ≈ 2 and declining toward the present.

SFRs also refers to single-family residences, a housing type consisting of a detached dwelling designed for one family. Characteristics typically include private entrances, an independent structure on its own lot, and limited or no shared walls with other units. SFRs contrast with multi-unit buildings such as townhouses and apartment complexes and are common in suburban or rural areas of the United States and other markets that favor detached housing. Real estate data may report SFR share of housing stock, median sale prices, and size metrics such as square footage. Market dynamics depend on zoning, land availability, and infrastructure.

In French telecommunications, SFR is the acronym for Société Française du Radiotéléphone, a major operator that provides mobile, fixed-line, and internet services. The acronym SFR can also appear in other disciplines as a shorthand for the star formation literature or housing terminology, depending on context. The plural form SFRs is used when referring to multiple instances of any of these meanings.