- ID:
- ivo://CDS.VizieR/J/A+AS/117/227
- Title:
- Dwarf effective temperatures
- Short Name:
- J/A+AS/117/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have applied the InfraRed Flux Method (IRFM) to a sample of 475 dwarfs and subdwarfs in order to derive their effective temperatures with a mean accuracy of about 1.5%. We have used the new homogeneous grid of theoretical model atmosphere flux distributions developed by Kurucz (1991, 1993) for the application of the IRFM. The atmospheric parameters of the stars cover, roughly, the ranges: 3500K<=T_eff_<=8000K; -3.5<=[Fe/H]<=+0.5; 3.5<=log(g)<=5. The monochromatic infrared fluxes at the continuum, and the bolometric fluxes are derived using recent results, which satisfy the accuracy requirements of the work.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/404/1745
- Title:
- Dwarf galaxies in Coma supercluster
- Short Name:
- J/MNRAS/404/1745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse Spitzer Multiband Imaging Photometer (MIPS) 24um observations, and Sloan Digital Sky Survey Data Release 7 optical broad-band photometry and spectra, to investigate the star formation (SF) properties of galaxies residing in the Coma supercluster region. We find that SF in dwarf galaxies is quenched only in the high-density environment at the centre of clusters and groups, but that passively evolving massive galaxies are found in all environments, indicating that massive galaxies can become passive via internal processes. The SF-density relation observed for the massive galaxies is weaker relative to the dwarfs, but both show a trend for the fraction of star-forming galaxies (f_SF_) declining to ~0 in the cluster cores. We find that active galactic nucleus activity is also suppressed among massive galaxies residing in the cluster cores.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/L15
- Title:
- Dwarf galaxies in Fornax cluster from NGFS
- Short Name:
- J/ApJ/813/L15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 158 previously undetected dwarf galaxies in the Fornax cluster central regions using a deep coadded u-, g-, and i-band image obtained with the Dark Energy Camera wide-field camera mounted on the 4-m Blanco telescope at the Cerro Tololo Interamerican Observatory as part of the Next Generation Fornax Survey (NGFS). The new dwarf galaxies have quasi-exponential light profiles, effective radii 0.1<r_e_<2.8kpc, and average effective surface brightness values 22.0<{mu}_i_<28.0mag/arcsec2. We confirm the existence of ultra-diffuse galaxies (UDGs) in the Fornax core regions that resemble counterparts recently discovered in the Virgo and Coma galaxy clusters. We also find extremely low surface brightness NGFS dwarfs, which are several magnitudes fainter than the classical UDGs. The faintest dwarf candidate in our NGFS sample has an absolute magnitude of M_i_=-8.0mag. The nucleation fraction of the NGFS dwarf galaxy sample appears to decrease as a function of their total luminosity, reaching from a nucleation fraction of >75% at luminosities brighter than M_i_~=-15.0mag to 0% at luminosities fainter than M_i_~=-10.0mag. The two-point correlation function analysis of the NGFS dwarf sample shows an excess on length scales below ~100 kpc, pointing to the clustering of dwarf galaxies in the Fornax cluster core.
- ID:
- ivo://CDS.VizieR/J/MNRAS/369/1375
- Title:
- Dwarf galaxies in NGC 1407 Group
- Short Name:
- J/MNRAS/369/1375
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The NGC 1407 Group stands out among nearby structures by its properties that suggest it is massive and evolved. It shares properties with entities that have been called fossil groups: the 1.4m differential between the dominant elliptical galaxy and the second brightest galaxy comes close to satisfying the definition that has been used to define the fossil class. There are few intermediate-luminosity galaxies, but a large number of dwarfs in the group. We estimate there are 250 group members to the depth of our survey. The slope of the faint end of the luminosity function (reaching M_R_=12) is alpha=-1.35. Velocities for 35 galaxies demonstrate that this group with one dominant galaxy has a mass of 7x10^13^M_{sun}_ and M/L_R_=340M_{sun}_/L_{sun}_. Two galaxies in close proximity to NGC 1407 have very large blueshifts. The most notable is the second brightest galaxy, NGC 1400, with a velocity of 1072km/s with respect to the group mean. We report the detection of X-ray emission from this galaxy and from the group.
- ID:
- ivo://CDS.VizieR/J/AJ/133/715
- Title:
- Dwarf galaxies of the Local Group
- Short Name:
- J/AJ/133/715
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an all-sky, deep optical survey for faint Local Group dwarf galaxies. Candidate objects were selected from the second Palomar Observatory Sky Survey and ESO/Science Research Council survey plates, and follow-up observations were performed to determine whether they were indeed overlooked members of the Local Group. Only two galaxies (Antlia and Cetus) were discovered this way out of 206 candidates. Based on internal and external comparisons, we estimate that our visual survey is more than 77% complete for objects larger than 1' in size and with a surface brightness greater than an extremely faint limit over the 72% of the sky not obstructed by the Milky Way.
- ID:
- ivo://CDS.VizieR/J/AJ/146/104
- Title:
- Dwarf galaxies surface brightness profiles. I.
- Short Name:
- J/AJ/146/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial surface brightness profiles of spiral galaxies are classified into three types: (I) single exponential, or the light falls off with one exponential to a break before falling off (II) more steeply, or (III) less steeply. Profile breaks are also found in dwarf disks, but some dwarf Type IIs are flat or increasing out to a break before falling off. Here we re-examine the stellar disk profiles of 141 dwarfs: 96 dwarf irregulars (dIms), 26 Blue Compact Dwarfs (BCDs), and 19 Magellanic-type spirals (Sms). We fit single, double, or even triple exponential profiles in up to 11 passbands: GALEX FUV and NUV, ground-based UBVJHK and H{alpha}, and Spitzer 3.6 and 4.5{mu}m. We find that more luminous galaxies have brighter centers, larger inner and outer scale lengths, and breaks at larger radii; dwarf trends with M_B_extend to spirals. However, the V-band break surface brightness is independent of break type, M_B_, and Hubble type. Dwarf Type II and III profiles fall off similarly beyond the breaks but have different interiors and IIs break ~twice as far as IIIs. Outer Type II and III scale lengths may have weak trends with wavelength, but pure Type II inner scale lengths clearly decrease from the FUV to visible bands whereas Type III inner scale lengths increase with redder bands. This suggests the influence of different star formation histories on profile type, but nonetheless the break location is approximately the same in all passbands. Dwarfs continue trends between profile and Hubble types such that later-type galaxies have more Type II but fewer Type I and III profiles than early-type spirals. BCDs and Sms are over-represented as Types III and II, respectively, compared to dIms.
- ID:
- ivo://CDS.VizieR/J/AJ/151/145
- Title:
- Dwarf galaxies surface brightness profiles. II.
- Short Name:
- J/AJ/151/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this second paper of a series, we explore the B-V, U-B, and FUV-NUV radial color trends from a multi-wavelength sample of 141 dwarf disk galaxies. Like spirals, dwarf galaxies have three types of radial surface brightness profiles: (I) single exponential throughout the observed extent (the minority), (II) down-bending (the majority), and (III) up-bending. We find that the colors of (1) Type I dwarfs generally become redder with increasing radius, unlike spirals which have a blueing trend that flattens beyond ~1.5 disk scale lengths, (2) Type II dwarfs come in six different "flavors", one of which mimics the "U" shape of spirals, and (3) Type III dwarfs have a stretched "S" shape where the central colors are flattish, become steeply redder toward the surface brightness break, then remain roughly constant beyond, which is similar to spiral Type III color profiles, but without the central outward bluing. Faint (-9>M_B_>-14) Type II dwarfs tend to have continuously red or "U" shaped colors and steeper color slopes than bright (-14>M_B_>-19) Type II dwarfs, which additionally have colors that become bluer or remain constant with increasing radius. Sm dwarfs and BCDs tend to have at least some blue and red radial color trend, respectively. Additionally, we determine stellar surface mass density ({Sigma}) profiles and use them to show that the break in {Sigma} generally remains in Type II dwarfs (unlike Type II spirals) but generally disappears in Type III dwarfs (unlike Type III spirals). Moreover, the break in {Sigma} is strong, intermediate, and weak in faint dwarfs, bright dwarfs, and spirals, respectively, indicating that {Sigma} may straighten with increasing galaxy mass. Finally, the average stellar surface mass density at the surface brightness break is roughly 1-2M_{Sun}_pc^-2^ for Type II dwarfs but higher at 5.9M_{Sun}_pc^-2^ or 27M_{Sun}_pc^-2^ for Type III BCDs and dIms, respectively.
- ID:
- ivo://CDS.VizieR/J/PASJ/64/63
- Title:
- Dwarf novae characterization using SDSS colors
- Short Name:
- J/PASJ/64/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed a method for estimating the orbital periods of dwarf novae from the Sloan Digital Sky Survey (SDSS) colors in quiescence using an artificial neural network. For typical objects below the period gap with sufficient photometric accuracy, we were able to estimate the orbital periods with accuracy to a 1{sigma} error of 22%. The error of the estimation is worse for systems with longer orbital periods. We have also developed a neural-network-based method for categorical classification. This method has proven to be efficient in classifying objects into three categories (WZ Sge type, SU UMa type, and SS Cyg/Z Cam type), and works for very faint objects to a limit of g=21mag. Using this method, we have investigated the distribution of the orbital periods of dwarf novae from a modern transient survey (Catalina Real-Time Survey).
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/2526
- Title:
- Dwarf novae outbursts properties
- Short Name:
- J/MNRAS/460/2526
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a statistical study of all measurable photometric features of a large sample of dwarf novae during their outbursts and superoutbursts. We used all accessible photometric data for all our objects to make the study as complete and up to date as possible. Our aim was to check correlations between these photometric features in order to constrain theoretical models which try to explain the nature of dwarf novae outbursts. We managed to confirm a few of the known correlations, that is the Stolz and Schoembs relation, the Bailey relation for long outbursts above the period gap, the relations between the cycle and supercycle lengths, amplitudes of normal and superoutbursts, amplitude and duration of superoutbursts, outburst duration and orbital period, outburst duration and mass ratio for short and normal outbursts, as well as the relation between the rise and decline rates of superoutbursts. However, we question the existence of the Kukarkin-Parenago relation but we found an analogous relation for superoutbursts. We also failed to find one presumed relation between outburst duration and mass ratio for superoutbursts. This study should help to direct theoretical work dedicated to dwarf novae.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/10
- Title:
- Dwarfs or giants? Stellar metallicities & distances
- Short Name:
- J/ApJ/886/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new fully data-driven algorithm that uses photometric data from the Canada-France Imaging Survey (CFIS; u), Pan-STARRS 1 (PS1; griz), and Gaia (G) to discriminate between dwarf and giant stars and to estimate their distances and metallicities. The algorithm is trained and tested using the Sloan Digital Sky Survey (SDSS)/SEGUE spectroscopic data set and Gaia photometric/astrometric data set. At [Fe/H]<-1.2, the algorithm succeeds in identifying more than 70% of the giants in the training/test set, with a dwarf contamination fraction below 30% (with respect to the SDSS/SEGUE data set). The photometric metallicity estimates have uncertainties better than 0.2dex when compared with the spectroscopic measurements. The distances estimated by the algorithm are valid out to a distance of at least ~80kpc without requiring any prior on the stellar distribution and have fully independent uncertainties that take into account both random and systematic errors. These advances allow us to estimate these stellar parameters for approximately 12 million stars in the photometric data set. This will enable studies involving the chemical mapping of the distant outer disk and the stellar halo, including their kinematics using the Gaia proper motions. This type of algorithm can be applied in the southern hemisphere to the first release of LSST data, thus providing an almost complete view of the external components of our Galaxy out to at least ~80kpc. Critical to the success of these efforts will be ensuring well-defined spectroscopic training sets that sample a broad range of stellar parameters with minimal biases. A catalog containing the training/test set and all relevant parameters within the public footprint of CFIS is available online.