- 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.
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- 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/A+AS/129/455
- Title:
- Dwarf galaxy candidates around interacting galaxies
- Short Name:
- J/A+AS/129/455
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the imaging of a sample of 12 interacting galaxies for which we have catalogued all potential dwarf systems in the vicinity of these strongly interacting galaxies. After careful cleaning of the images and applying a restrictive S/N criterion we have identified, measured and catalogued all possible extended objects in each field. On the frames, covering 11.4x10.5arcmins, on the order of 100 non-stellar, faint, extended objects were found around each interacting galaxy. The vast majority (>98%) of these objects had not been previously identified. The number of expected objects in the magnitude range R=18-19.5 exceeds the expected count of background galaxies. This supports the possibility that a density enhancement of extended objects around some interacting galaxies results from the addition of a locally formed dwarf galaxy population.
- 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/A+AS/107/365
- Title:
- Dwarfs and subdwarfs IR photometry
- Short Name:
- J/A+AS/107/365
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a long term programme of broad band JHK photometry, for a sample of 360 late type stars, made at the Observatorio del Teide (Tenerife, Spain) are presented.
- 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.
1719. DX Eri variability
- ID:
- ivo://CDS.VizieR/J/A+A/309/787
- Title:
- DX Eri variability
- Short Name:
- J/A+A/309/787
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of nearly simultaneous monitoring of uvby light and HeI667.81nm line-profile variations of the equatorial Be star DX Eri in November 1991. They are analysed along with numerous uvby photometry in the period 1986-1995.
- ID:
- ivo://CDS.VizieR/J/A+A/459/391
- Title:
- Dynamics of NGC 4636 globular cluster system
- Short Name:
- J/A+A/459/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first dynamical study of the globular cluster system of NGC 4636. It is the southernmost giant elliptical galaxy of the Virgo cluster and is claimed to be extremely dark matter dominated, according to X-ray observations. Globular clusters are used as dynamical tracers to investigate, by stellar dynamical means, the dark matter content of this galaxy. Several hundred medium resolution spectra were acquired at the VLT with FORS 2/MXU. We obtained velocities for 174 globular clusters in the radial range 0.90'<R<15.5', or 0.5-9R_e_ in units of effective radius. Assuming a distance of 15Mpc, the clusters are found at projected galactocentric distances in the range 4 to 70kpc, the overwhelming majority within 30kpc. The measured line-of-sight velocity dispersions are compared to Jeans-models.
