Discovery of an Extended Ultraviolet Disk in the Nearby Galaxy NGC 4625

By A. Gil de Paz, B. Madore, S. Boissier, R. Swaters, C. Popescu, R. Tuffs, K. Sheth, Robert C. Kennicutt Jr., L. Bianchi, D. Thilker and 1 more. 2005

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Recent far-UV (FUV) and near-UV (NUV) observations of the nearby galaxy NGC 4625 made by the Galaxy Evolution Explorer (GALEX) show the presence of an extended UV disk reaching to 4 times the optical radius of the galaxy. The UV-to-optical colors suggest that the bulk of the stars in the disk of NGC 4625 are currently being formed, providing a unique opportunity to study today the physics of star formation under conditions similar to those when the normal disks of spiral galaxies like the Milky Way first formed. In the case of NGC 4625, the star formation in the extended disk is likely to be triggered by interaction with NGC 4618 and possibly also with the newly discovered galaxy NGC 4625A. The positions of the FUV complexes in the extended disk coincide with peaks in the H I distribution. The masses of these complexes are in the range 103-104 M☉, with their Hα emission (when present) being dominated by ionization from single stars.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/3cf7754ed62e0e2181c10c5fa707c1e27f89628e

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Citations in the corpus

A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA (2013, methodology): “The same pattern in the abundance has been described in the case of the extended UV disks discovered by GALEX (Gil de Paz et al. 2005; Thilker et al. 2007), which show oxygen abundances that are rarely below one-tenth of the solar value.”
A Search for Extended Ultraviolet Disk (XUV-Disk) Galaxies in the Local Universe (2007, background): “Most of the XUV-disk stellar complexes are too faint for individual detection by SDSS. NGC 4625 is interacting with NGC 4618 and possibly NGC 4625A (Gil de Paz et al. 2005).”
Radial Variation of Attenuation and Star Formation in the Largest Late-Type Disks Observed with GALEX (2006, background): “…is nevertheless often used with the same meaning as “attenuation”. the UV also shows us low levels of star formation (XUV galaxies, e.g. Gil de Paz et al. 2005; Thilker et al. 2005), in regions with such low dust content that the far-infrared emission is undetected by IRAS, and that the…”
THE SPATIALLY RESOLVED STAR FORMATION LAW FROM INTEGRAL FIELD SPECTROSCOPY: VIRUS-P OBSERVATIONS OF NGC 5194 (2009, background): “Recently, the detection of widespread UV emission beyond the Hα brightness profile cutoff in the outer disks of many nearby galaxies (Gil de Paz et al. 2005; Thilker et al. 2005; Boissier et al. 2007) , has raised questions about the proportionality between the Hα emission and the SFR in the low…”
Beyond Inside-Out Growth: Formation and Evolution of Disk Outskirts (2007, background): “Furthermore, the discovery of UV emission at radii well beyond the Hα emission cutoff (Gil de Paz et al. 2005; Thilker et al. 2005, 2007), the observational evidence for inside-out disk growth (Muñoz-Mateos et al. 2007), and detections of disk breaks in the distant universe (Pérez 2004; Trujillo…”
The structure of galactic disks - Studying late-type spiral galaxies using SDSS (2006, background): “However, there is compelling evidence of star-formation inthe far outer regions of spiral galaxies (e.g. Ferguson et al., 1998; Cuillandre et al., 2001; Thilker et al., 2005; Gil de Paz et al., 2005), well beyond the break of the observed broken exponential structure (Pohlen et al., 2002).”
EXTREMELY INEFFICIENT STAR FORMATION IN THE OUTER DISKS OF NEARBY GALAXIES (2010, background): “…of extended UV (XUV) disks in a large number of nearby galaxies was one of the major achievements of the GALEX mission (Thilker et al. 2005; Gil de Paz et al. 2005; Thilker et al. 2007; Gil de Paz et al. 2007b; Boissier et al. 2007; Zaritsky & Christlein 2007; Thilker et al. 2009; Hunter et al.…”
A GALEX ULTRAVIOLET IMAGING SURVEY OF GALAXIES IN THE LOCAL VOLUME (2010, background): “…was the detection of FUV emission extending to several times the optical disks of the nearby systems M83 (Thilker et al. 2005) and NGC 4625 (Gil de Paz et al. 2005), and it was reported that the amount and extent of the star formation in these “XUV-disks” was greater than formerly seen in images…”
The GALEX Ultraviolet Atlas of Nearby Galaxies (2006, background): “…adds to the lack of spatial resolution and depth of previous UV data and, in some cases, to the availability of UV data in only one band, which leads to a loss of sensitivity to the strength of the UVupturn, best traced by the FUV NUV color (see Gil de Paz et al. 2005a and references therein).”
Star Formation in the Milky Way and Nearby Galaxies (2012, background): “In exceptional cases (e.g., NGC5236=M83, NGC4625) the star formation extends to 3–4 times the normal R25 optical radius, to the edge of the HI disk (Thilker et al. 2005; Gil de Paz et al. 2005).”