H{alpha} DOTS: A CATALOG OF FAINT EMISSION-LINE OBJECTS DISCOVERED IN NARROWBAND IMAGES

Journal Article · Fri Jun 15 04:00:00 EDT 2012 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/143/6/145· OSTI ID:22034437

Kellar, Jessica A; Wegner, Gary ^[1]; Salzer, John J; Williams, Anna ^[2]; Gronwall, Caryl ^[3]

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1. Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755 (United States)
2. Department of Astronomy, Indiana University, 727 East Third Street, Bloomington, IN 47405 (United States)
3. Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)

During a wide-field narrowband H{alpha} imaging survey, we noted the presence of numerous isolated emission-line point sources in the data. These objects could represent ultra-low-luminosity galaxies at low-redshift (detection via H{alpha}), isolated extragalactic H II regions associated with the galaxy targeted by the original observation, or background galaxies or QSOs where strong emission lines (most often [O III] {lambda}5007) redshift into our narrowband filter. We have carried out a systematic search for these 'H{alpha} dots' in over 200 15 Multiplication-Sign 15 arcmin fields. To date we have cataloged 61 candidate emission-line sources in roughly 11.7 deg{sup 2}. The sample has a median R magnitude of 19.5, and detects objects as faint as R = 22.6. Follow-up spectroscopy reveals that {approx}85% of the candidates are bona fide emission-line objects, with roughly 60% of the real sources being lower-redshift objects (detection via H{alpha}) and 40% being higher-redshift objects detected via [O III] emission or some other emission line. Here we present the results of our initial survey and follow-up spectroscopy. We use our sample to study the properties (including star-formation rates and metal abundances) of low-luminosity star-forming galaxies in the nearby universe and of low-metallicity star-forming galaxies at z Almost-Equal-To 0.33.

• OSTI ID: 22034437
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 6 Vol. 143; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
CATALOGS
DETECTION
ELEMENT ABUNDANCE
EMISSION SPECTROSCOPY
GALAXIES
HYDROGEN
IMAGES
LUMINOSITY
METALS
OPTICAL FILTERS
PHOTON EMISSION
POINT SOURCES
RED SHIFT
STARS
UNIVERSE