- ID:
- ivo://CDS.VizieR/J/A+A/592/A40
- Title:
- Photometry of SN 2013gh and iPTF13dge
- Short Name:
- J/A+A/592/A40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Temporal variability of narrow absorption lines in high-resolution spectra of Type Ia supernovae (SNe Ia) is studied to search for circumstellar matter. Time series which resolve the profiles of absorption lines such as NaI D or CaII H&K are expected to reveal variations due to photoionisation and subsequent recombination of the gases. The presence, composition, and geometry of circumstellar matter may hint at the elusive progenitor system of SNe Ia and could also affect the observed reddening law. To date, there are few known cases of time-varying NaI D absorption in SNe Ia, all of which occurred during relatively late phases of the supernova (SN) evolution. Photoionisation, however, is predicted to occur during the early phases of SNe Ia, when the supernovae peak in the ultraviolet. We attempt, therefore, to observe early-time absorption-line variations by obtaining high-resolution spectra of SNe before maximum light We have obtained photometry and high-resolution spectroscopy of SNe Ia 2013gh and iPTF 13dge, to search for absorption- line variations. Furthermore, we study interstellar absorption features in relation to the observed photometric colours of the SNe. Results. Both SNe display deep NaI D and CaII H&K absorption features. Furthermore, small but significant variations are detected in a feature of the NaI D profile of SN 2013gh. The variations are consistent with either geometric effects of rapidly moving or patchy gas clouds or photoionisation of NaI gas at R~=10^19^cm from the explosion. Our analysis indicates that it is necessary to focus on early phases to detect photoionisation effects of gases in the circumstellar medium of SNe Ia. Different absorbers such as NaI and CaII can be used to probe for matter at different distances from the SNe. The nondetection of variations during early phases makes it possible to put limits on the abundance of the species at those distances.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/473/149
- Title:
- Photometry of sources in IRAS 16362-4845 cluster
- Short Name:
- J/A+A/473/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IRAS 16362-4845 star-forming site in the RCW 108 complex contains an embedded compact cluster that includes some massive O-type stars. Star formation in the complex, and in particular in IRAS 16362-4845, has been proposed to be externally triggered by the action of NGC 6193. We present a photometric study of the IRAS 16362-4845 cluster sensitive enough to probe the massive brown dwarf regime. In particular, we try to verify an apparent scarcity of solar-type and low-mass stars reported in a previous paper (Comeron et al., 2005A&A...433..955C).
- ID:
- ivo://CDS.VizieR/J/AJ/123/2822
- Title:
- Photometry of southern NLTT stars
- Short Name:
- J/AJ/123/2822
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BVRI photometry of 180 bright, southern nearby-star candidates. The stars were selected from the New Luyten Two-Tenths proper-motion catalog (Cat. <I/98>) based on optical/infrared colors, constructed by combining Luyten's m_r_ estimates with near-infrared photometry from the Two Micron All Sky Survey (Cat. <B/2mass>) . Photometric parallaxes derived from V-Ks, V-I, and I-J colors, combined with the limited available astrometry, show that as many as 108 stars may lie within 20pc of the Sun. Of these, 53 are new to nearby-star catalogs, including three within 10pc of the Sun.
- ID:
- ivo://CDS.VizieR/J/A+A/529/A25
- Title:
- Photometry of star clusters in 5 nearby gal.
- Short Name:
- J/A+A/529/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies have started to cast doubt on the assumption that most stars are formed in clusters. Observational studies of field stars and star cluster systems in nearby galaxies can lead to better constraints on the fraction of stars forming in clusters. Ultimately this may lead to a better understanding of star formation in galaxies, and galaxy evolution in general. We aim to constrain the amount of star formation happening in long-lived clusters for four galaxies through the homogeneous, simultaneous study of field stars and star clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/467/1003
- Title:
- Photometry of star clusters in NGC 1380
- Short Name:
- J/A+A/467/1003
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 1380 is a lenticular galaxy located near the center of the Fornax Cluster, northeast of NGC 1399. The globular cluster system of this galaxy was previously studied only from the ground. Recent studies of similar early-type galaxies, specially lenticular ones, reveal the existence of star clusters that apparently break up the traditional open/globular cluster dichotomy. With higher quality photometry from HST/WFPC2 we study the star clusters in NGC 1380, measuring their magnitudes, colours, sizes and projected distances from the center of the galaxy. We used deep archival HST/WFPC2 in the B and V bands. We built colour magnitude diagrams from which we selected a sample of cluster candidates. We also analysed their colour distribution and measured their sizes. Based on their location in the luminosity-size diagram we estimated probabilities of them being typical globular clusters as those found in the Galaxy. A total of about 570 cluster candidates were found down to V=26.5. We measured sizes for approximately 200 of them. The observed colour distribution has three apparent peaks. Likewise for the size distribution. We identified the smaller population as being mainly typical globular clusters, while the more extended objects have small probabilities of being such objects. Different correlations between absolute magnitudes, sizes, colours and location were inferred for these cluster sub-populations. Most extended clusters (Reff>4pc) share similar properties to the diffuse star clusters reported to inhabit luminous early-type galaxies in the Virgo galaxy cluster such as being of low surface brightness and fainter than MV~-8. We also report on a small group of (R_eff_~10pc), -8<MV<-6, red clusters located near the centre of NGC 1380, which may be interpreted as faint fuzzies.
- ID:
- ivo://CDS.VizieR/J/AJ/151/58
- Title:
- Photometry of stars at NAOR and ASV in 2013-2014
- Short Name:
- J/AJ/151/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 2m telescope of the Bulgarian National Astronomical Observatory at Rozhen, observations of 271 double or multiple stars were carried out during seven nights in 2013 and 2014. This is the eighth series of measurements of CCD frames of double and multiple stars obtained at Rozhen. Also in 2013 and 2014, using the 0.6m telescope of the Serbian Astronomical Station on the mountain of Vidojevica, observations of 343 double or multiple stars were carried out during 21 nights. This is the third series of measurements of CCD frames of double and multiple stars obtained at this station. In this paper, we present the results for the position angle and angular separation for 721 pairs and residuals for 126 pairs with published orbital elements or linear solutions. These observations have angular separations in the range from 1.24'' to 202.30'', with a median angular separation of 7.17''. We also present eight linear solutions that have been calculated for the first time.
- ID:
- ivo://CDS.VizieR/J/AJ/158/215
- Title:
- Photometry of stars at NAOR and ASV in 2017-2018
- Short Name:
- J/AJ/158/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We give the results of CCD observations for 789 double or multiple stars obtained during 2017 and 2018. These observations were carried out at both the Serbian Astronomical Station on the mountain of Vidojevica (ASV) and the Bulgarian National Astronomical Observatory at Rozhen (NAOR). They were performed using three telescopes, the 1.4 and 0.6 m telescopes at ASV, and the 2 m telescope at NAOR. The total of 1196 measurements (position angle and angular separation) for the 939 pairs is presented. Out of this number, 55 pairs have calculated orbital or linear elements and for them the residuals are given. Some pairs have measurements for several epochs. Measured angular separations are in the interval from 1.51" to 208.81", with a median separation of 4.16". Two new pairs and linear elements for three pairs, which are calculated for the first time, are also presented.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A144
- Title:
- Photometry of stars in the LeoA HST WFC3 field
- Short Name:
- J/A+A/614/A144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- LeoA is an isolated gas-rich dwarf irregular galaxy of low stellar mass and metallicity residing at the outskirts of the Local Group. Ages of the stellar populations in LeoA range from ~10Myr to ~10Gyr. A large stellar halo (up to the deprojected distance of ~1.7kpc was discovered based on Subaru wide-field photometry of red giant branch stars. We analysed HST WFC3 archive observation data in the field that is partly located beyond the previously known limits of the LeoA galaxy. We performed photometry of star-like objects in the F475W and F814W passbands and studied the spatial distribution of the Leo A stars below the horizontal branch. We report a discovery of stellar halo populations (subgiants and faint red giants) in the Leo A galaxy extending up to ~2.3kpc deprojected distance from the galaxy centre. Analysis of the colour-magnitude diagram suggests old (>5Gyr) stellar populations of very low metallicity (Z~0.0001).
- ID:
- ivo://CDS.VizieR/J/AJ/161/138
- Title:
- Photometry of 38708 stars in W3 complex with HST
- Short Name:
- J/AJ/161/138
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We have used archival infrared images obtained with the Wide Field Camera 3 on board the Hubble Space Telescope to constrain the initial mass function of low-mass stars and brown dwarfs in the W3 star-forming region. The images cover 438arcmin^2^, which encompasses the entire complex, and were taken in the filters F110W, F139M, and F160W. We have estimated extinctions for individual sources in these data from their colors and have dereddened their photometry accordingly. By comparing an area of the images that contains the richest concentration of previously identified W3 members to an area that has few members and is dominated by background stars, we have estimated the luminosity function for members of W3 with masses of 0.03-0.4M{sun}. That luminosity function closely resembles data in typical nearby star-forming regions that have much smaller stellar populations than W3 ( ~500 versus several thousand objects). Thus, we do not find evidence of significant variations in the initial mass function of low-mass stars and brown dwarfs with star-forming conditions, which is consistent with recent studies of other distant massive star-forming regions.
- ID:
- ivo://CDS.VizieR/J/ApJ/812/133
- Title:
- 1889-2015 photometry of Stingray nebula
- Short Name:
- J/ApJ/812/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Up until around 1980, the Stingray was an ordinary B1 post-AGB star, but then it suddenly sprouted bright emission lines like in a planetary nebula (PN), and soon after this the Hubble Space Telescope (HST) discovered a small PN around the star, so apparently we have caught a star in the act of ionizing a PN. We report here on a well-sampled light curve from 1889 to 2015, with unique coverage of the prior century plus the entire duration of the PN formation plus three decades of its aftermath. Surprisingly, the star anticipated the 1980s ionization event by declining from B=10.30 in 1889 to B=10.76 in 1980. Starting in 1980, the central star faded fast, at a rate of 0.20mag/yr, reaching B=14.64 in 1996. This fast fading is apparently caused by the central star shrinking in size. From 1994 to 2015, the V-band light curve is almost entirely from the flux of two bright [OIII] emission lines from the unresolved nebula, and it shows a consistent decline at a rate of 0.090mag/yr. This steady fading (also seen in the radio and infrared) has a timescale equal to that expected for ordinary recombination within the nebula, immediately after a short-duration ionizing event in the 1980s. We are providing the first direct measure of the rapidly changing luminosity of the central star on both sides of a presumed thermal pulse in 1980, with this providing a strong and critical set of constraints, and these are found to sharply disagree with theoretical models of PN evolution.
