Current Star Formation Rate Research Articles

The far-infrared properties of optically selected emission-line galaxies

A high-sensitivity sample of IRAS-detected emission-line galaxies (ELGs) is used to investigate the FIR properties of these galaxies and the relative selection biases of the UM Curtis Schmidt and IRAS surveys. Color-color diagrams indicate that the FIR emission from the UM ELGs is due primarily to warm dust heated directly by the active star-forming regions that are responsible for the strong optical emission lines. The FIR luminosity of the UM ELGs is found to correlate with both H-beta and blue luminosities, suggesting that the current star-formation rate in these objects is more closely coupled to the past star-formation history than is generally acknowledged.

Near-infrared mass-to-light ratios in galaxies - Stellar mass and star formation in the heart of the Whirlpool

The observed stellar population in the solar neighborhood is used to derive a relationship between the local stellar mass density and the visual and near-IR brightness, which is then extended to a wide range of galaxies. This technique is applied to near-IR (J, H, and K) images of the central 2.3 kpc (50 arcsec) of the Whirlpool Galaxy (M51, NGC 5194). It is estimated that the current high rate of star formation can last no more than about another 10-million years, and that, if a large fraction of the stars in the nucleus of M51 was created in periods of enhanced formation, the duty cycle for such events is about 5 percent.

CO Observations of Bright IRAS Galaxies

CO emission has been detected from 75 bright infrared galaxies with CZ = 2 000 – 16 000 km/s. These include the most distant and the most luminous galaxies (Arp 55, IR 1713+63) yet detected in CO. All of these galaxies are rich in molecular gas with Mtotal (H2) = 2 × 109 −6x1010 M⊙, and they have a strong far-infrared excess, with LFIR/LB = 2-40 and LFIR (40-400μ) = 1010 – 3 × 1012 L⊙. The primary luminosity source appears to be star formation in molecular clouds. A strong correlation is found between the FIR and 21-cm continuum flux, implying that the IMF is independent of the star formation rate. The ratio LFIR/M(H2) provides a measure of the current rate of star-formation, which is found to be a factor 3-20 larger in these galaxies than for the ensemble of molecular clouds in the Milky Way. VLA maps plus a few high resolution (14″-30″) CO (1-0) and CO (2-1) maps suggest that most of the luminosity comes from core regions 1-3 kpc in size. The abnormal concentration of molecular gas in these galactic cores is presumably the result of a collision or strong interaction with a nearby companion.

CO detections and IRAS observations of bright radio spiral galaxies at CZ equal or less than 9000 kilometers per second

view Abstract Citations (247) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS CO detections and IRAS observations of bright radio spiral galaxies at cz<9000 kilometers per second. Sanders, D. B. ; Mirabel, I. F. Abstract CO emission has been detected from 20 of 21 bright radio spirals with strong extended nuclear sources, including the most distant (NGC 7674) and the most luminous (IC 4553 = Arp 220, NGC 6240) galaxies yet detected in CO. All of these galaxies are rich in molecular gas, with M total(H2) = 3 x 10 to the 8th - 2 x 10 to the 10th solar masses. IRAS observations show that they have a strong far-infrared (FIR) excess, with L(FIR)/L(B) approximately equal to 1-35 and L(FIR) (40-400 microns) approximately equal to 10 to the 10th - 10 to the 12th L solar masses. The primary luminosity source for these radio cores appears to be star formation in molecular clouds. A strong correlation is found between the FIR and extended 21 cm continuum flux, implying that the fraction of massive stars formed is independent of the star formation rate. The ratio L(FIR)/M(H2) provides a measure of the current rate of star formation, which is found to be a factor 3-20 larger in these galaxies than for the ensemble of molecular clouds in the Milky Way. At these rates their molecular gas will be depleted in about 10 to the 8th yr. Publication: The Astrophysical Journal Pub Date: November 1985 DOI: 10.1086/184561 Bibcode: 1985ApJ...298L..31S Keywords: Carbon Monoxide; Interstellar Gas; Molecular Clouds; Radio Galaxies; Spiral Galaxies; Stellar Evolution; Far Infrared Radiation; Galactic Nuclei; Infrared Astronomy Satellite; Milky Way Galaxy; Star Formation Rate; Astrophysics full text sources ADS | data products SIMBAD (39) NED (35)

Star-forming properties and histories of dwarf irregular galaxies - Down but not out

Spectroscopic and imaging data designed to study star formation processes in a sample of dwarf irregular (Irr) galaxies are presented. Although the low-surface brightness dwarf Irr's have much H I gas with which to form stars, the galaxy-wide star formation rates are low: typically about 10 to the -10th solar mass/yr/sq pc. The properties of the low-surface brightness dwarf Irr's are consistent with a constant star formation rate equal to their current rate over approximately a Hubble time. The typical star-forming regions in the dwarfs are on average smaller and less luminous than those in the giant Irr's, although the size distributions cover the same range, while similar to giant Irr's in many global parameters, the dwarfs have lower current and historical star formation rates per unit area. Dwarf Irr's have low metallicities relative to spirals, with typical nebular oxygen abundances falling between those of the LMC and SMC.

H-alpha observations of spiral galaxies in Cancer, A1367, and Coma

view Abstract Citations (104) References (32) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS H-alpha observations of spiral galaxies in Cancer, A 1367, and Coma. Kennicutt, R. C., Jr. ; Bothun, G. D. ; Schommer, R. A. Abstract The authors have used large aperture Hα photometry of 65 spiral galaxies in the Cancer, Coma, and Abell 1367 clusters to compare the ionized-gas contents and star-formation rates in cluster and field spirals. Overall, the authors do not observe any significant deficiency of Hα emission in the cluster members. Emission strength correlates strongly with integrated galaxy colors, but only weakly with H I content. All three clusters contain several galaxies with unusually strong Hα emission, including several H I-poor objects in Coma and A1367. Thus, spirals which appear "anemic" in their morphology or exhibit weak Hα emission are not necessarily H I poor; conversely, H I poor spirals can show strong Hα emission, indicating relatively high current star-formation rates. Gas depletion time scales for some objects in the core of Coma are significantly shorter than the field, indicating rapid stellar and gaseous evolution. Publication: The Astronomical Journal Pub Date: September 1984 DOI: 10.1086/113625 Bibcode: 1984AJ.....89.1279K Keywords: Astronomical Photometry; H Alpha Line; Spiral Galaxies; Star Clusters; Stellar Evolution; Cosmic Gases; Emission Spectra; Spectral Line Width; Star Formation Rate; Astrophysics full text sources ADS | data products NED (66) SIMBAD (62)

A survey of H-alpha emission in normal galaxies

view Abstract Citations (410) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A survey of H-alpha emission in normal galaxies. Kennicutt, R. C., Jr. ; Kent, S. M. Abstract The combined results of photometric and spectrophotometric surveys of H-alpha emission in 200 field and Virgo cluster galaxies are presented. In most spiral galaxies the emission is dominated by normal disk H II regions, and consequently the integrated Balmer flux of a galaxy can be used as a quantitative index of its current OB star formation rate. Uncertainties due to instrumental effects, nuclear emission, forbidden-line N II emission, and extinction by dust, are evaluated. The integrated emission of a galaxy is strongly correlated with its Hubble type and color, confirming the earlier conclusions of Cohen (1976). Emission among galaxies of a given type varies greatly, however, and in most cases is due to a real dispersion in star formation activity. This activity is only weakly correlated with galaxy luminosity or H I content, suggesting that some other parameter is more important. Publication: The Astronomical Journal Pub Date: August 1983 DOI: 10.1086/113399 Bibcode: 1983AJ.....88.1094K Keywords: Astronomical Spectroscopy; Emission Spectra; H Alpha Line; Spiral Galaxies; Stellar Evolution; Virgo Galactic Cluster; B Stars; Cosmic Dust; H Ii Regions; Hubble Constant; Instrument Errors; Nitrogen; Nuclear Reactions; O Stars; Star Formation Rate; Astrophysics full text sources ADS | data products SIMBAD (203) NED (203)

Infrared emission and star formation in the central regions of the galaxy IC 342

The face-on Scd galaxy IC 342 has been studied at infrared wavelengths between 1.2 μm and 250 μm and at centimeter radio wavelengths. At 10 μm the nucleus is bright and extended on a scale of 200 pc, with a double structure unlike that of the stars seen at 2 μm. The infrared emission between 8 and 250 μm probably arises from heated dust grains in star formation regions in the disk of the galaxy. The radio emission comes from a region with many of the same spatial features as the 10 μm source; it appears to include both thermal and nonthermal sources. IC 342 is intermediate in luminosity between the Galaxy and NGC 253; the difference can probably be accounted for by a difference in the current rate of star formation at their centers.