Ultra-flat galaxies selected from RFGC catalog. I. The sample properties

Караченцева, В. Е.; Kudrya, Yu. N.; Караченцев, И. Д.; Макаров, Д. И.; Мelnyk, О. V.

doi:10.1134/s1990341316010016

Cited by 23 publications

(41 citation statements)

References 20 publications

(25 reference statements)

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“…(1) the number of the galaxy in the RFGC catalog; (2) the equatorial coordinates; (3,4) the "blue" angular diameter in arcmin and apparent "blue" axial ratio from RFGC; (5) the heliocentric radial velocity of the galaxy in km s −1 ; (6) the effective wavelength of the filter (Å) in which the galaxy was exposed; (7) the exposure time in the Hα filter in sec; (8)…”

Section: Resultsmentioning

confidence: 99%

Ha Images of Ultra-Flat Edge-On Spiral Galaxies

et al. 2020

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We present the Hα images of ultra-flat (UF) spiral galaxies seen practically edge-on. The galaxies have the angular diameter in the B band a > 1 . ′ 9 and the apparent axial ratio (a/b) > 10. We found that their Hα images look, on average, almost two times thinner than those in the red continuum. The star-formation rate in the studied objects, determined from the Hα flux, is in good agreement with that calculated from the F U V flux from the GALEX survey if we use the modified Verheijen and Sancisi formula taking into account the internal extinction in the UF galaxies. The logarithm of the specific star-formation rate in the UF galaxies shows a small scatter, 0.19, with a smooth decrease from −10.4 for dwarf spirals to −10.7 for massive ones. The relative amount of the hydrogen mass in UF disks varies from about 50% in dwarf disks to about 8% in massive ones. Structural distortions are less common in the UF galaxies (about 16%) than those in thick (less isolated) disks of edge-on spiral galaxies. On the cosmic time scale, 13.7 Gyr, large spiral disks are more efficient "engines" for gas processing into stars than dwarf spirals. * Electronic address: skai@sao.ru

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Section: Resultsmentioning

confidence: 99%

Ha Images of Ultra-Flat Edge-On Spiral Galaxies

et al. 2020

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“…′ 0 is 70%, and the completeness of about 90% is achieved at the angular diameter of a blue = 1. ′ 2 [29]. We have strengthened the selection criteria to ensure the acceptable completeness (90%), reduce the selection effects, and at the same time to have a rather large number of galaxies remaining.…”

Section: Galaxiesmentioning

confidence: 99%

Ultra-flat galaxies selected from RFGC catalog. III. Star formation rate

2017

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We examine the star formation properties of galaxies with very thin disks selected from the Revised Flat Galaxy Catalog (RFGC). The sample contains 333 ultra-flat galaxies (UFG) at high Galactic latitudes, |b| > 10 • , with a blue major angular diameter of a ≥ 1. ′ 2, blue and red apparent axial ratios of (a/b) b > 10, (a/b) r > 8.5 and radial velocities within 10 000 km s −1. As a control sample for them we use a population of 722 more thick RFGC galaxies with (a/b) b > 7, situated in the same volume. The UFG distribution over the sky indicates them as a population of quite isolated galaxies. We found that the specific star formation rate, sSF R FUV , determined via the FUV GALEX flux, increases steadily from the early type to late type disks for both the UFG and RFGC-UFG samples, showing no significant mutual difference within each morphological type T. The population of UFG disks has the average H I-mass-to-stellar-mass ratio by (0.25 ± 0.03) dex higher than that of RFGC-UFG galaxies. Being compared with arbitrary orientated disks of the same type, the ultra-flat edge-on galaxies reveal that their total H I mass is hidden by self-absorption on the average by approximately 0.20 dex. We demonstrate that using the robust stellar mass estimate via B − K-color and galaxy type T for the thin disks, together with a nowaday accounting for internal extinction, yields their sSF R quantities definitely lying below the limit of −9.4 dex (yr −1). The collected observational data on UFG disks imply that their average star formation rate in the past has been approximately three times the current SF R. The UFG galaxies have also sufficient amount of gas to support their observed SF R over the following nearly 9 Gyrs.

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“…This sample covers the entire northern and southern sky, except for the region of the Milky Way (|b| < 10 • ) and has an approximately 90% completeness up to the angular diameter of a B = 1. ′ 2 [11]. From the analysis of this fairly representative sample, we concluded that about 60% of UF galaxies have not got any close neighbors within the projection distance of R p = 750 kpc and the radial velocity differences of | ∆V |< 500 km s −1 .…”

Section: Introductionmentioning

confidence: 80%

Ultra-flat galaxies selected from RFGC catalog. II. Orbital estimates of halo masses

2016

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We used the Revised Flat Galaxy Catalog (RFGC) to select 817 ultra-flat (UF) edge-on disk galaxies with blue and red apparent axial ratios of (a/b) B > 10.0 and (a/b) R > 8.5. The sample covering the whole sky, except the Milky Way zone, contains 490 UF galaxies with measured radial velocities. Our inspection of the neighboring galaxies around them revealed only 30 companions with radial velocity difference of | ∆V |< 500 km s −1 inside the projected separation of R p < 250 kpc. Wherein, the wider area around the UF galaxy within R p < 750 kpc contains no other neighbors brighter than the UF galaxy itself in the same velocity span. The resulting sample galaxies mostly belong to the morphological types Sc, Scd, Sd. They have a moderate rotation velocity curve amplitude of about 120 km s −1 and a moderate K-band luminosity of about 10 10 L ⊙ . The median difference of radial velocities of their companions is 87 km s −1 , yielding the median orbital mass estimate of about 5 × 10 11 M ⊙ . Excluding six probable non-isolated pairs, we obtained a typical halo-mass-to-stellar-mass of UF galaxies of about 30, what is almost the same one as in the principal spiral galaxies, like M 31 and M 81 in the nearest groups. We also note that ultra-flat galaxies look two times less "dusty" than other spirals of the same luminosity.

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Ultra-flat galaxies selected from RFGC catalog. I. The sample properties

Cited by 23 publications

References 20 publications

Ha Images of Ultra-Flat Edge-On Spiral Galaxies

Ha Images of Ultra-Flat Edge-On Spiral Galaxies

Ultra-flat galaxies selected from RFGC catalog. III. Star formation rate

Ultra-flat galaxies selected from RFGC catalog. II. Orbital estimates of halo masses

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