- ID:
- ivo://CDS.VizieR/J/A+A/306/924
- Title:
- Optical spectrum of HR 4049
- Short Name:
- J/A+A/306/924
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution optical spectra (UES/WHT) of the extreme metal-poor post-AGB star HR 4049 were obtained at four different orbital phases. The spectra cover the wavelength region from 3650A to 10850A at a resolution of R=5.2x10^4^. These observations are supplemented with four high-resolution spectra of the NaI D1 & D2 and CaII K lines at R=~10^5^ (CAT/CES). The optical spectrum shows 217 spectral lines: the Balmer series (H{alpha} - H35), the Paschen series (P9 - P23), NI, OI and numerous CI lines. We show that the lines of H{alpha}, H{beta}, H{gamma} and NaI D show significant changes in profile between different observation dates. Nine components were identified in the profile of the NaI D lines of which three are circumstellar and six interstellar. The stronger CI lines are asymmetric and we derive a post-AGB mass-loss of {dot}(M)=6+/-4x10^-7^M_{sun}_/yr from the asymmetry. The [OI]6300A line has been detected in emission at the system velocity and we argue that the emission is from an almost edge-on disk with a radius of about 20R_*_. HR 4049 is at J2000 position: 00 42 45.8 - 20 21 36
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/404/545
- Title:
- Optical spectrum of M 2-24
- Short Name:
- J/A+A/404/545
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained medium-resolution, deep optical long-slit spectra of the bulge planetary nebula (PN) M 2-24. The spectrum covers the wavelength range from 3610-7330{AA}. Over two hundred emission lines have been detected. The spectra show a variety of optical recombination lines (ORLs) from C, N, O and Ne ions. The diagnostic diagram shows significant density and temperature variations across the nebula. Our analysis suggests that the nebula has a dense central emission core. The nebula was thus studied by dividing it into two regions: 1) an high ionization region characterized by an electron temperature of T_e_=16300K and a density of logN_e_(cm^-3^)=6.3; and 2) a low ionization region represented by T_e_=11400K and logN_e_(cm^-3^)=3.7. A large number of ORLs from C, N, O and Ne ions have been used to determine the abundances of these elements relative to hydrogen. In general, the resultant abundances are found to be higher than the corresponding values deduced from collisionally excited lines (CELs). This bulge PN is found to have large enhancements in two {alpha}-elements, magnesium and neon.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A68
- Title:
- Optical spectrum of the blazar PKS 0447-439
- Short Name:
- J/A+A/545/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PKS 0447-439 is one of the BL Lacertae objects that have been detected at very high energy. There has been a recent report of a lower limit of z>=1.246 for the redshift of this blazar, challenging the current paradigm in which very high-energy {gamma}-rays cannot freely propagate in the z>~1 universe. In this research note, we present a new MagE/Magellan spectrum of PKS 0447-439 with exquisite signal-to-noise (S/N>150 at 6500{AA}). Our analysis confirms the presence of the previously-reported absorption line at 6280{AA}, which we identify, however, with a known telluric absorption, invalidating the claim that this blazar lies at z>1. Since no other extragalactic spectral features are detected, we cannot establish a redshift based on our spectrum.
- ID:
- ivo://CDS.VizieR/J/ApJ/895/49
- Title:
- Optical spectrum of ZTF18abvkwla and its host galaxy
- Short Name:
- J/ApJ/895/49
- Date:
- 16 Mar 2022 00:26:26
- Publisher:
- CDS
- Description:
- We present ZTF18abvkwla (the "Koala"), a fast blue optical transient discovered in the Zwicky Transient Facility (ZTF) One-Day Cadence (1DC) Survey. ZTF18abvkwla has a number of features in common with the groundbreaking transient AT2018cow: blue colors at peak (g-r~-0.5mag), a short rise time from half-max of under two days, a decay time to half-max of only three days, a high optical luminosity (M_g.peak_~-20.6mag), a hot (>~40000K) featureless spectrum at peak light, and a luminous radio counterpart. At late times ({Delta}>80days), the radio luminosity of ZTF18abvkwla ({nu}L_{nu}_>~10^40^erg/s at 10GHz, observer-frame) is most similar to that of long-duration gamma-ray bursts (GRBs). The host galaxy is a dwarf starburst galaxy (M~5x10^8^M{odot}, SFR~7M{odot}/yr) that is moderately metal-enriched (log[O/H]~8.5), similar to the hosts of GRBs and superluminous supernovae. As in AT2018cow, the radio and optical emission in ZTF18abvkwla likely arise from two separate components: the radio from fast- moving ejecta ({Gamma}{beta}c>0.38c) and the optical from shock-interaction with confined dense material (<0.07M{sun} in ~10^15^cm). Compiling transients in the literature with t_rise_<5days and M_peak_<-20mag, we find that a significant number are engine-powered, and suggest that the high peak optical luminosity is directly related to the presence of this engine. From 18 months of the 1DC survey, we find that transients in this rise-luminosity phase space are at least two to three orders of magnitude less common than CC SNe. Finally, we discuss strategies for identifying such events with future facilities like the Large Synoptic Survey Telescope, as well as prospects for detecting accompanying X-ray and radio emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/274
- Title:
- Optical to NIR spectra of nova V2676 Oph 2012
- Short Name:
- J/ApJ/835/274
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectrophotometric and near-infrared (NIR) photometric observations of the nova V2676 Oph covering the period from 2012 March 29 through 2015 May 8. The optical spectra and photometry of the nova have been taken from SMARTS and Asiago; the NIR photometry was obtained from SMARTS and Mt. Abu. The spectra were dominated by strong H I lines from the Balmer series, FeII, NI, and [OI] lines in the initial days, typical of an Fe II type nova. The measured FWHM for the H{beta} and H{alpha} lines was 800-1200km/s. There was pronounced dust formation starting 90 days after the outburst. The J-K color was the largest among recent dust-forming novae.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A147
- Title:
- Optimizing exoplanet transit searches
- Short Name:
- J/A+A/537/A147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate a method to increase the efficiency of a targeted exoplanet search with the transit technique by preselecting a subset of candidates from large catalogs of stars. Assuming spin-orbit alignment, this can be achieved by considering stars that have a higher probability to be oriented nearly equator-on (inclination close to 90{deg}).
- ID:
- ivo://CDS.VizieR/J/ApJS/238/37
- Title:
- Opt. & NIR spectral atlas of 16 2MASS NIR-red AGNs
- Short Name:
- J/ApJS/238/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present medium-resolution spectra (R~2000-4000) at 0.4-1.0{mu}m and 0.7-2.5{mu}m of 16 active galactic nuclei (AGNs) selected with red color in the near-infrared (NIR) of J-K>2.0mag at z~0.3. We fit the H{beta}, H{alpha}, P{beta}, and P{alpha} lines from these spectra to obtain their luminosities and line widths. We derive the E(B-V) color excess values of the NIR-red AGNs using two methods, one based on the line-luminosity ratios and another based on the continuum slopes. The two E(B-V) values agree with each other at rms dispersion ~0.249. About half of the NIR-red AGNs have g'-K<5 magnitude, and we find that these NIR-red, but blue in optical-NIR AGNs, have E(B-V)~0, suggesting that a significant fraction of the NIR color-selected red AGNs are unobscured or only mildly obscured. After correcting for the dust extinction, we estimate the black hole (BH) masses and the bolometric luminosities of the NIR-red AGNs using the Paschen lines to calculate their Eddington ratios ({lambda}Edd). The median Eddington ratios of nine NIR-red AGNs (log({lambda}_Edd_~-0.654+/-0.176) are only mildly higher than those of unobscured type 1 AGNs (log({lambda}_Edd_~-0.961+/-0.008). Moreover, we find that the MBH-{sigma}* relation for three NIR-red AGNs is consistent with that of unobscured type 1 AGNs at similar redshift. These results suggest that the NIR-red color selection alone is not effective at picking up dusty, intermediate-stage AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/854/145
- Title:
- Opt. photometry & NIR spectroscopy of Wolf 1130
- Short Name:
- J/ApJ/854/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following the discovery of the T8 subdwarf WISE J200520.38+542433.9 (Wolf 1130C), which has a proper motion in common with a binary (Wolf 1130AB) consisting of an M subdwarf and a white dwarf, we set out to learn more about the old binary in the system. We find that the A and B components of Wolf 1130 are tidally locked, which is revealed by the coherence of more than a year of V-band photometry phase-folded to the derived orbital period of 0.4967 days. Forty new high-resolution, near-infrared spectra obtained with the Immersion Grating Infrared Spectrometer (IGRINS) provide radial velocities and a projected rotational velocity (vsini) of 14.7+/-0.7km/s for the M subdwarf. In tandem with a Gaia parallax-derived radius and verified tidal locking, we calculate an inclination of i=29{deg}+/-2{deg}. From the single-lined orbital solution and the inclination we derive an absolute mass for the unseen primary (1.24_-0.15_^+0.19^M_{sun}_). Its non-detection between 0.2 and 2.5{mu}m implies that it is an old (>3.7Gyr) and cool (T_eff_<7000K) ONe white dwarf. This is the first ultramassive white dwarf within 25pc. The evolution of Wolf 1130AB into a cataclysmic variable is inevitable, making it a potential SN Ia progenitor. The formation of a triple system with a primary mass >100 times the tertiary mass and the survival of the system through the common-envelope phase, where ~80% of the system mass was lost, is remarkable. Our analysis of Wolf 1130 allows us to infer its formation and evolutionary history, which has unique implications for understanding low-mass star and brown dwarf formation around intermediate-mass stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/L30
- Title:
- Opt. spectra of the interstellar object 2I/Borisov
- Short Name:
- J/ApJ/889/L30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 2I/Borisov is the first-ever observed interstellar comet (and the second detected interstellar object (ISO)). It was discovered on 2019 August 30 and has a heliocentric orbital eccentricity of ~3.35, corresponding to a hyperbolic orbit that is unbound to the Sun. Given that it is an ISO, it is of interest to compare its properties-such as composition and activity-with the comets in our solar system. This study reports low-resolution optical spectra of 2I/Borisov. The spectra were obtained by the MDM Observatory Hiltner 2.4m telescope/Ohio State Multi-Object Spectrograph (on 2019 October 31.5 and November 4.5, UT). The wavelength coverage spanned from 3700 to 9200{AA}. The dust continuum reflectance spectra of 2I/Borisov show that the spectral slope is steeper in the blue end of the spectrum (compared to the red). The spectra of 2I/Borisov clearly show CN emission at 3880{AA}, as well as C2 emission at both 4750 and 5150{AA}. Using a Haser model to covert the observed fluxes into estimates for the molecular production rates, we find Q(CN)=2.4+/-0.2x10^24^s^-1^, and Q(C_2_)=(5.5+/-0.4)x10^23^s^-1^ at the heliocentric distance of 2.145au. Our Q(CN) estimate is consistent with contemporaneous observations, and the Q(C_2_) estimate is generally below the upper limits of previous studies. We derived the ratio Q(C_2_)/Q(CN)=0.2+/-0.1, which indicates that 2I/Borisov is depleted in carbon-chain species, but is not empty. This feature is not rare for the comets in our solar system, especially in the class of Jupiter-family comets.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/L38
- Title:
- Opt. spectroscopic investigations of 2I/Borisov
- Short Name:
- J/ApJ/889/L38
- Date:
- 17 Jan 2022 00:14:14
- Publisher:
- CDS
- Description:
- The composition of comets in the solar system comes in multiple groups thought to encode information about their formation in different regions of the outer protosolar disk. The recent discovery of the second interstellar object, 2I/Borisov, allows for spectroscopic investigations into its gas content and a preliminary classification of it within the solar system comet taxonomies to test the applicability of planetesimal formation models to other stellar systems. We present spectroscopic and imaging observations from 2019 September 20 through October 26 from the Bok, MMT telescope (formerly the Multiple Mirror Telescope, Mount Hopkins, Arizona), and Large Binocular Telescopes. We identify CN in the comet's spectrum and set precise upper limits on the abundance of C_2_ on all dates in October. We use a Haser model to convert our integrated fluxes to production rates and find Q(CN)=(1.1-1.9)*10^24^mols/s increasing over 2019 October 1 to 26, consistent with contemporaneous observations. We set our lowest upper limit on a C_2_ production rate, Q(C_2_)<1.6*10^23^mols/s on 2019 October 10. The measured upper limit ratio for that date Q(C_2_)/Q(CN)<0.1 indicates that 2I/Borisov is strongly in the (carbon-chain) "depleted" taxonomic group if there is any C_2_ production at all. Most "depleted" comets are Jupiter-family comets (JFCs), perhaps indicating a similarity in formation conditions between the most depleted of the JFCs and 2I/Borisov. More work is needed to understand the applicability of our knowledge of solar system comet taxonomies onto interstellar objects and we discuss future work that could help to clarify the usefulness of the approach.
