arXiv subjects

A. Moro-Martin

Publications and source records attributed to A. Moro-Martin.

43 records · Page 3Linked to original sources

arXiv2004

Optical and Infrared Photometry of the Type Ia Supernovae 1991T, 1991bg, 1999ek, 2001bt, 2001cn, 2001cz, and 2002bo

We present optical and/or infrared photometry of the Type Ia supernovae SN 1991T, SN 1991bg, SN 1999ek, SN 2001bt, SN 2001cn, SN 2001cz, and SN 2002bo. All but one of these supernovae have decline rate parameters Delta m_15(B) close to the median value of 1.1 for the whole class of Type Ia supernovae. The addition of these supernovae to the relationship between the near-infrared absolute magnitudes and Delta m_15(B) strengthens the previous relationships we have found, in that the maximum light absolute magnitudes are essentially independent of the decline rate parameter. (SN 1991bg, the prototype of the subclass of fast declining Type Ia supernovae, is a special case.) The dispersion in the Hubble diagram in JHK is only ~0.15 mag. The near-infrared properties of Type Ia supernovae continue to be excellent measures of the luminosity distances to the supernova host galaxies, due to the need for only small corrections from the epoch of observation to maximum light, low dispersion in absolute magnitudes at maximum light, and the minimal reddening effects in the near-infrared.

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arXiv2004

Stability of Terrestrial Planets in the Habitable Zone of Gl 777 A, HD 72659, Gl 614, 47 Uma and HD 4208

We have undertaken a thorough dynamical investigation of five extrasolar planetary systems using extensive numerical experiments. The systems Gl 777 A, HD 72659, Gl 614, 47 Uma and HD 4208 were examined concerning the question of whether they could host terrestrial like planets in their habitable zones (=HZ). First we investigated the mean motion resonances between fictitious terrestrial planets and the existing gas giants in these five extrasolar systems. Then a fine grid of initial conditions for a potential terrestrial planet within the HZ was chosen for each system, from which the stability of orbits was then assessed by direct integrations over a time interval of 1 million years. The computations were carried out using a Lie-series integration method with an adaptive step size control. This integration method achieves machine precision accuracy in a highly efficient and robust way, requiring no special adjustments when the orbits have large eccentricities. The stability of orbits was examined with a determination of the Renyi entropy, estimated from recurrence plots, and with a more straight forward method based on the maximum eccentricity achieved by the planet over the 1 million year integration. Additionally, the eccentricity is an indication of the habitability of a terrestrial planet in the HZ; any value of e>0.2 produces a significant temperature difference on a planet's surface between apoapse and periapse. The results for possible stable orbits for terrestrial planets in habitable zones for the five systems are summarized as follows: for Gl 777 A nearly the entire HZ is stable, for 47 Uma, HD 72659 and HD 4208 terrestrial planets can survive for a sufficiently long time, while for Gl 614 our results exclude terrestrial planets moving in stable orbits within the HZ.

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arXiv2003

Warm Molecular Hydrogen and Ionized Neon in the HH2 Outflow

We report on spectro-imaging observations of the Herbig-Haro 2 outflow with the ISOCAM camera onboard the Infrared Space Observatory (ISO). The [Ne II}] 12.81 microns and [Ne III]15.55 microns lines are detected only towards the jet working surface (HH 2H), consistent with the high excitation of this knot in the optical range, while H2 pure rotational emission is found all over the shocked region HH 2. The low energy transition S(2) traces warm gas (T approx. 400K) peaked towards knots E-F and extended ejecta (T approx. 250-380) with masses of a few 0.001 solar mass in the high-velocity CO outflow extending between the powering source and HH 2. Such emission could arise from low-velocity C-type shocks (v= 10-15 km/s). The higher transitions S(3)-S(7) trace the emission of hot shocked gas (T= 1000-1400K) from individual optical knots in the HH 2 region. The ortho to para (OTP) ratio exhibits large spatial variations between 1.2 (E) and 2.5 (H), well below its value at LTE. The emission of the S(3)-S(7) lines is well accounted for by planar C-shock models with a typical velocity V= 20-30 km/s propagating into a medium of density 10^4-10^5 cm-3 with an initial OTP ratio close to 1 in the pre-shock gas. In the leading edge of the jet, where the geometry of the emission allows a simple modelling, a good agreement is found with velocities derived from the optical proper motions measured in the ionized gas.

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arXiv2001

The Distance to SN 1999em from the Expanding Photosphere Method

We present optical and IR spectroscopy of the first two months of evolution of the Type II SN 1999em. We combine these data with high-quality optical/IR photometry beginning only three days after shock breakout, in order to study the performance of the ``Expanding Photosphere Method'' (EPM) in the determination of distances. With this purpose we develop a technique to measure accurate photospheric velocities by cross-correlating observed and model spectra. The application of this technique to SN 1999em shows that we can reach an average uncertainty of 11% in velocity from an individual spectrum. Our analysis shows that EPM is quite robust to the effects of dust. In particular, the distances derived from the VI filters change by only 7% when the adopted visual extinction in the host galaxy is varied by 0.45 mag. The superb time sampling of the BVIZJHK light-curves of SN 1999em permits us to study the internal consistency of EPM and test the dilution factors computed from atmosphere models for Type II plateau supernovae. We find that, in the first week since explosion, the EPM distances are up to 50% lower than the average, possibly due the presence of circumstellar material. Over the following 65 days, on the other hand, our tests lend strong credence to the atmosphere models, and confirm previous claims that EPM can produce consistent distances without having to craft specific models to each supernova. This is particularly true for the VI filters which yield distances with an internal consistency of 4%. From the whole set of BVIZJHK photometry, we obtain an average distance of 7.5+/-0.5 Mpc, where the quoted uncertainty (7%) is a conservative estimate of the internal precision of the method obtained from the analysis of the first 70 days of the supernova evolution.

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arXiv2001

Infrared and Millimetric Study of the Young Outflow Cepheus E

The Cepheus E outflow has been studied in the mid and far infrared using the ISO CAM and LWS instruments, and at millimetric wavelengths using OVRO. In the near and mid-IR, its morphology is similar to that expected for a jet driven outflow, where the leading bow shocks entrain and accelerate the surrounding molecular gas. As expected, fine structure atomic/ionic emission lines arise from the bow shocks, at both the Mach Disk and the stagnation tip, where J-shocks are dominant. The H2, H2O and CO molecular emission could arise further `downstream' at the bow shock wings where the shocks (v = 8-35 km/s) are oblique and more likely to be C-type. The 13CO emission arises from entrained molecular gas and a compact high velocity emission is observed, together with an extended low velocity component that almost coincides spatially with the H2 near-IR emission. The millimetric continuum emission shows two sources. We identify one of them with IRAS 23011+6126, postulating is the driver of the Cepheus E outflow; the other, also an embedded source, is likely to be driving one of other outflows observed in the region.

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arXiv2000

The Optical Spectroscopic Evolution of V1974 Cygni (Nova Cygni 1992)

Optical observations of nova V1974 Cygni (Cygni 1992), spanning a 4 year period, have been used to study its spectroscopic evolution. The data cover a wavelength range from $\sim 3200 - 8000$ Åand follows the nebular evolutionary phase of the ejecta. We have modeled the integrated fluxes by means of the photoionization code CLOUDY. The models were run at a {\it fixed} abundance value for the most prominent elements (i.e. H, He, C, O, N, Ne, Fe, etc) over the entire time sequence. It is possible to constrain from this simple model some of the physical conditions of the gaseous emitting region, like temperature and density. Compared with previous studies of the gas abundances of the heavy elements, we found that smaller enhancements of S, N and Ar, and comparable values for O and Fe, are able to reproduce the observations. The time evolution of the surface temperature of the ionizing source and the high-ionization iron lines [Fe VII] 6087 Åand [Fe X] 6374 Å, is similar to what it is observed in the soft X-rays. The early line profiles can be reproduced using a simple kinematical model consisting of an equatorial ring and polar caps, expanding at a velocity of $\sim 1100$ km/s. This simple model also approximates the structure of the resolved shell observed by HST. Considering the complicated structure of the shell, the lack of well defined values of its gas density and our limited knowledge of the time evolution of the surface temperature of the photoionization source, the comparison between models and observations agrees remarkably well.

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arXiv1999

A Molecular Counterpart to the Herbig-Haro 1-2 Flow

We present high angular resolution (12"-24") and high sensitivity 12CO and 13CO J=2-1 and J=1-0 observations of the HH 1-2 outflow. The observations show the molecular counterpart, moving with a velocity of approx. 30 km/s, of the optical bipolar system driven by the VLA 1 embedded source. Along the optical jet there are certain regions where the molecular gas reaches deprojected velocities of 100-200 km/s, and that we interpret as the molecular jet. The bipolar CO outflow has a length of approx. 260" with a curved morphology towards the North where it extends beyond the HH 1 object (approx. 120") . Two new molecular outflows have been detected, one arising from IRAS 05339-0647 which excites the HH 147 optical flow and another powered by VLA 2 which drives the HH 144 optical outflow. The molecular outflow driven by the VLA 3 source is also clearly detected and spatially resolved from the VLA 1 main outflow.

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