Search

Start Over Subject optical astronomy
2821. Photometry of SDSS J152419.33+220920.0
ID:
ivo://CDS.VizieR/J/A+A/554/A25
Title:
Photometry of SDSS J152419.33+220920.0
Short Name:
J/A+A/554/A25
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new photometry of the faint (g~19mag) and poorly studied cataclysmic variable SDSS J152419.33+220920.0, analyze its light curve and provide an accurate ephemeris for this system. Time-resolved CCD differential photometry was carried out using the 1.5m and 0.84m telescopes at the Observatorio Astronomico Nacional at San Pedro Martir. All observations were taken in white-light (no filter). This table contains the differential photometry for the system obtained during six nights (covering more than twenty primary eclipse cycles in more than three years). The reference for the photometry is SDSS J152415.99+220804.0, g=17.77 (marked as star C1 in the paper). The associated errors are 0.02mag outside eclipse. The information for each observation run is presented in Table 1 and the light-curves using this data are presented in Figure 4. Our light curve analysis shows that only two fundamental frequencies are present, corresponding to the orbital period and a modulation with twice this frequency. We determine the accurate ephemeris of the system to be HJD_eclipse_=2454967.6750(1)+0.06531866661(1)E. A double-hump orbital period modulation, a standing feature in several bounce-back systems at quiescence, is present at several epochs. However, we found no other evidence to support the hypothesis that this system belongs to the post-minimum orbital-period systems.
2822. Photometry of SN 2009bb
ID:
ivo://CDS.VizieR/J/ApJ/728/14
Title:
Photometry of SN 2009bb
Short Name:
J/ApJ/728/14
Date:
21 Oct 2021
Publisher:
CDS
Description:
Ultraviolet, optical, and near-infrared photometry and optical spectroscopy of the broad-lined Type Ic supernova (SN) 2009bb are presented, following the flux evolution from -10 to +285 days past B-band maximum. Thanks to the very early discovery, it is possible to place tight constraints on the SN explosion epoch. The expansion velocities measured from near maximum spectra are found to be only slightly smaller than those measured from spectra of the prototype broad-lined SN 1998bw associated with GRB 980425. Fitting an analytical model to the pseudobolometric light curve of SN 2009bb suggests that 4.1+/-1.9M_{sun}_ of material was ejected with 0.22+/-0.06M_{sun} of it being ^56^Ni. The resulting kinetic energy is 1.8+/-0.7x10^52^erg. This, together with an absolute peak magnitude of M_B_=-18.36+/-0.44, places SN 2009bb on the energetic and luminous end of the broad-lined Type Ic (SN Ic) sequence. Detection of helium in the early time optical spectra accompanied with strong radio emission and high metallicity of its environment makes SN 2009bb a peculiar object. Similar to the case for gamma-ray bursts (GRBs), we find that the bulk explosion parameters of SN 2009bb cannot account for the copious energy coupled to relativistic ejecta, and conclude that another energy reservoir (a central engine) is required to power the radio emission. Nevertheless, the analysis of the SN 2009bb nebular spectrum suggests that the failed GRB detection is not imputable to a large angle between the line-of-sight and the GRB beamed radiation. Therefore, if a GRB was produced during the SN 2009bb explosion, it was below the threshold of the current generation of {gamma}-ray instruments.
2823. Photometry of SN 2003cg
ID:
ivo://CDS.VizieR/J/MNRAS/369/1880
Title:
Photometry of SN 2003cg
Short Name:
J/MNRAS/369/1880
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical and near-infrared photometry and spectroscopy of the Type Ia SN 2003cg, which exploded in the nearby galaxy NGC 3169. The observations cover a period between 8.5 and +414d post-maximum. SN 2003cg is a normal but highly reddened Type Ia event. Its B magnitude at maximum Bmax=15.94+/-0.04 and {Delta}m15(B)_obs_=1.12+/-0.04 [{Delta}m15(B)_intrinsic_=1.25+/-0.05]. Allowing RV to become a free parameter within the Cardelli et al. (1989ApJ...345..245C) extinction law, simultaneous matches to a range of colour curves of normal SNe Ia yielded E(B-V)=1.33+/-0.11, and RV=1.80+/-0.19. While the value obtained for RV is small, such values have been invoked in the past, and may imply a grain size which is small compared with the average value for the local interstellar medium.
2824. Photometry of SN 2008D
ID:
ivo://CDS.VizieR/J/ApJ/692/L84
Title:
Photometry of SN 2008D
Short Name:
J/ApJ/692/L84
Date:
21 Oct 2021
Publisher:
CDS
Description:
On 2008 January 9.56 UT, SN 2008D was discovered while following up an unusually bright X-ray transient (XT) in the nearby spiral galaxy NGC 2770. We present early optical spectra (obtained 1.75 days after the XT) which allowed the first identification of the object as a supernova (SN) at redshift z=0.007. These spectra were acquired during the initial declining phase of the light curve, likely produced in the stellar envelope cooling after shock breakout, and rarely observed. They exhibit a rather flat spectral energy distribution with broad undulations, and a strong, W-shaped feature with minima at 3980 and 4190{AA} (rest frame). We also present extensive spectroscopy and photometry of the SN during the subsequent photospheric phase. Unlike SNe associated with gamma-ray bursts, SN 2008D displayed prominent He features and is therefore of Type Ib.
2825. Photometry of SN 2015da
ID:
ivo://CDS.VizieR/J/A+A/635/A39
Title:
Photometry of SN 2015da
Short Name:
J/A+A/635/A39
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper we report the results of the first ~four years of spectroscopic and photometric monitoring of the Type IIn supernova SN 2015da (also known as PSN J13522411+3941286, or iPTF16tu). The supernova exploded in the nearby spiral galaxy NGC 5337 in a relatively highly extinguished environment. The transient showed prominent narrow Balmer lines in emission at all times and a slow rise to maximum in all bands. In addition, early observations performed by amateur astronomers give a very well-constrained explosion epoch. The observables are consistent with continuous interaction between the supernova ejecta and a dense and extended H-rich circumstellar medium. The presence of such an extended and dense medium is difficult to reconcile with standard stellar evolution models, since the metallicity at the position of SN 2015da seems to be slightly subsolar. Interaction is likely the mechanism powering the light curve, as confirmed by the analysis of the pseudo bolometric light curve, which gives a total radiated energy >~10^51^erg. Modeling the light curve in the context of a supernova shock breakout through a dense circumstellar medium allowed us to infer the mass of the prexisting gas to be ~=8M_{sun}_, with an extreme mass-loss rate for the progenitor star ~=0.6M_{sun}_/yr, suggesting that most of the circumstellar gas was produced during multiple eruptive events. Near- and mid-infrared observations reveal a fluxexcess in these domains, similar to those observed in SN 2010jl and other interacting transients, likely due to preexisting radiatively heated dust surrounding the supernova. By modeling the infrared excess, we infer a mass >~0.4x10^-3^M_{sun}_ for the dust.
2826. Photometry of SN 2013gh and iPTF13dge
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.
2827. Photometry of southern NLTT stars
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.
2828. Photometry of star clusters in NGC 1380
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.
2829. Photometry of stars at NAOR and ASV in 2013-2014
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.
2830. Photometry of stars at NAOR and ASV in 2017-2018
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.